Commit the lockfile for 0.74 (#7719)

Was missed in #7718

.github/workflows/ci.yml

@@ -15,8 +15,22 @@ jobs:
         # builds to link against a too-new-for-many-Linux-installs glibc version. Consider
         # revisiting this when 20.04 is closer to EOL (April 2025)
         platform: [windows-latest, macos-latest, ubuntu-20.04]
+        style: [default, dataframe]
         rust:
           - stable
+        include:
+          - style: default
+            flags: ""
+          - style: dataframe
+            flags: "--features=dataframe "
+        exclude:
+          # only test dataframes on Ubuntu (the fastest platform)
+          - platform: windows-latest
+            style: dataframe
+          - platform: macos-latest
+            style: dataframe
+
+
 
     runs-on: ${{ matrix.platform }}
     env:
@@ -32,7 +46,7 @@ jobs:
         run: cargo fmt --all -- --check
 
       - name: Clippy
-        run: cargo clippy --workspace --exclude nu_plugin_* -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect
+        run: cargo clippy --workspace ${{ matrix.flags }}--exclude nu_plugin_* -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect
 
   nu-tests:
     env:
@@ -99,8 +113,9 @@ jobs:
 
       - run: python -m pip install tox
 
+        # Get only the latest tagged version for stability reasons
       - name: Install virtualenv
-        run: git clone https://github.com/pypa/virtualenv.git
+        run: git clone https://github.com/pypa/virtualenv.git && cd virtualenv && git checkout $(git describe --tags | cut -d - -f 1)
         shell: bash
 
       - name: Test Nushell in virtualenv

Cargo.lock

@@ -80,6 +80,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "anes"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
+
 [[package]]
 name = "ansi-str"
 version = "0.5.0"
@@ -104,7 +110,7 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "220044e6a1bb31ddee4e3db724d29767f352de47445a6cd75e1a173142136c83"
 dependencies = [
- "nom 7.1.1",
+ "nom",
  "vte",
 ]
 
@@ -479,7 +485,7 @@ version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6fac387a98bb7c37292057cffc56d62ecb629900026402633ae9160df93a8766"
 dependencies = [
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
@@ -542,6 +548,33 @@ dependencies = [
  "phf_codegen 0.11.1",
 ]
 
+[[package]]
+name = "ciborium"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0c137568cc60b904a7724001b35ce2630fd00d5d84805fbb608ab89509d788f"
+dependencies = [
+ "ciborium-io",
+ "ciborium-ll",
+ "serde",
+]
+
+[[package]]
+name = "ciborium-io"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "346de753af073cc87b52b2083a506b38ac176a44cfb05497b622e27be899b369"
+
+[[package]]
+name = "ciborium-ll"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "213030a2b5a4e0c0892b6652260cf6ccac84827b83a85a534e178e3906c4cf1b"
+dependencies = [
+ "ciborium-io",
+ "half",
+]
+
 [[package]]
 name = "clang-sys"
 version = "1.4.0"
@@ -555,13 +588,23 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "2.34.0"
+version = "3.2.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a0610544180c38b88101fecf2dd634b174a62eef6946f84dfc6a7127512b381c"
+checksum = "71655c45cb9845d3270c9d6df84ebe72b4dad3c2ba3f7023ad47c144e4e473a5"
 dependencies = [
  "bitflags",
- "textwrap 0.11.0",
- "unicode-width",
+ "clap_lex",
+ "indexmap",
+ "textwrap 0.16.0",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2850f2f5a82cbf437dd5af4d49848fbdfc27c157c3d010345776f952765261c5"
+dependencies = [
+ "os_str_bytes",
 ]
 
 [[package]]
@@ -673,15 +716,16 @@ dependencies = [
 
 [[package]]
 name = "criterion"
-version = "0.3.6"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b01d6de93b2b6c65e17c634a26653a29d107b3c98c607c765bf38d041531cd8f"
+checksum = "e7c76e09c1aae2bc52b3d2f29e13c6572553b30c4aa1b8a49fd70de6412654cb"
 dependencies = [
+ "anes",
  "atty",
  "cast",
+ "ciborium",
  "clap",
  "criterion-plot",
- "csv",
  "itertools",
  "lazy_static",
  "num-traits",
@@ -690,7 +734,6 @@ dependencies = [
  "rayon",
  "regex",
  "serde",
- "serde_cbor",
  "serde_derive",
  "serde_json",
  "tinytemplate",
@@ -699,9 +742,9 @@ dependencies = [
 
 [[package]]
 name = "criterion-plot"
-version = "0.4.5"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2673cc8207403546f45f5fd319a974b1e6983ad1a3ee7e6041650013be041876"
+checksum = "6b50826342786a51a89e2da3a28f1c32b06e387201bc2d19791f622c673706b1"
 dependencies = [
  "cast",
  "itertools",
@@ -1167,7 +1210,7 @@ checksum = "e11dcc7e4d79a8c89b9ab4c6f5c30b1fc4a83c420792da3542fd31179ed5f517"
 dependencies = [
  "cfg-if 1.0.0",
  "rustix",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -1188,7 +1231,7 @@ dependencies = [
  "cfg-if 1.0.0",
  "libc",
  "redox_syscall",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -2110,6 +2153,15 @@ dependencies = [
  "cfg-if 1.0.0",
 ]
 
+[[package]]
+name = "lru"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6e8aaa3f231bb4bd57b84b2d5dc3ae7f350265df8aa96492e0bc394a1571909"
+dependencies = [
+ "hashbrown",
+]
+
 [[package]]
 name = "lscolors"
 version = "0.12.0"
@@ -2216,16 +2268,6 @@ dependencies = [
  "autocfg",
 ]
 
-[[package]]
-name = "meval"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f79496a5651c8d57cd033c5add8ca7ee4e3d5f7587a4777484640d9cb60392d9"
-dependencies = [
- "fnv",
- "nom 1.2.4",
-]
-
 [[package]]
 name = "miette"
 version = "5.3.0"
@@ -2262,6 +2304,16 @@ version = "0.3.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2a60c7ce501c71e03a9c9c0d35b861413ae925bd979cc7a4e30d060069aaac8d"
 
+[[package]]
+name = "mime_guess"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4192263c238a5f0d0c6bfd21f336a313a4ce1c450542449ca191bb657b4642ef"
+dependencies = [
+ "mime",
+ "unicase",
+]
+
 [[package]]
 name = "minimal-lexical"
 version = "0.2.1"
@@ -2305,7 +2357,7 @@ dependencies = [
  "libc",
  "log",
  "wasi 0.11.0+wasi-snapshot-preview1",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -2420,12 +2472,6 @@ version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 
-[[package]]
-name = "nom"
-version = "1.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5b8c256fd9471521bcb84c3cdba98921497f1a331cbc15b8030fc63b82050ce"
-
 [[package]]
 name = "nom"
 version = "7.1.1"
@@ -2446,7 +2492,7 @@ dependencies = [
  "indent_write",
  "joinery",
  "memchr",
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
@@ -2478,11 +2524,12 @@ dependencies = [
 
 [[package]]
 name = "nu"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "assert_cmd",
  "atty",
  "chrono",
+ "criterion",
  "crossterm 0.24.0",
  "ctrlc",
  "hamcrest2",
@@ -2532,7 +2579,7 @@ dependencies = [
 
 [[package]]
 name = "nu-cli"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "atty",
  "chrono",
@@ -2561,7 +2608,7 @@ dependencies = [
 
 [[package]]
 name = "nu-color-config"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "nu-ansi-term",
  "nu-engine",
@@ -2575,7 +2622,7 @@ dependencies = [
 
 [[package]]
 name = "nu-command"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "Inflector",
  "alphanumeric-sort",
@@ -2609,8 +2656,8 @@ dependencies = [
  "log",
  "lscolors",
  "md-5",
- "meval",
  "mime",
+ "mime_guess",
  "notify",
  "nu-ansi-term",
  "nu-color-config",
@@ -2631,7 +2678,9 @@ dependencies = [
  "num-format",
  "num-traits",
  "once_cell",
+ "open",
  "pathdiff",
+ "percent-encoding",
  "polars",
  "powierza-coefficient",
  "proptest",
@@ -2674,7 +2723,7 @@ dependencies = [
 
 [[package]]
 name = "nu-engine"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "chrono",
  "nu-glob",
@@ -2686,7 +2735,7 @@ dependencies = [
 
 [[package]]
 name = "nu-explore"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "ansi-str 0.7.2",
  "crossterm 0.24.0",
@@ -2706,14 +2755,14 @@ dependencies = [
 
 [[package]]
 name = "nu-glob"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "doc-comment",
 ]
 
 [[package]]
 name = "nu-json"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "linked-hash-map",
  "num-traits",
@@ -2722,7 +2771,7 @@ dependencies = [
 
 [[package]]
 name = "nu-parser"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "bytesize",
  "chrono",
@@ -2739,7 +2788,7 @@ dependencies = [
 
 [[package]]
 name = "nu-path"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "dirs-next",
  "omnipath",
@@ -2748,10 +2797,9 @@ dependencies = [
 
 [[package]]
 name = "nu-plugin"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "bincode",
- "criterion",
  "nu-engine",
  "nu-protocol",
  "rmp",
@@ -2762,7 +2810,7 @@ dependencies = [
 
 [[package]]
 name = "nu-pretty-hex"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "heapless",
  "nu-ansi-term",
@@ -2771,13 +2819,14 @@ dependencies = [
 
 [[package]]
 name = "nu-protocol"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "byte-unit",
  "chrono",
  "chrono-humanize",
  "fancy-regex",
  "indexmap",
+ "lru",
  "miette",
  "nu-json",
  "nu-test-support",
@@ -2794,7 +2843,7 @@ dependencies = [
 
 [[package]]
 name = "nu-system"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "atty",
  "chrono",
@@ -2812,7 +2861,7 @@ dependencies = [
 
 [[package]]
 name = "nu-table"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "atty",
  "json_to_table",
@@ -2828,7 +2877,7 @@ dependencies = [
 
 [[package]]
 name = "nu-term-grid"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "nu-utils",
  "unicode-width",
@@ -2836,7 +2885,7 @@ dependencies = [
 
 [[package]]
 name = "nu-test-support"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "getset",
  "hamcrest2",
@@ -2850,7 +2899,7 @@ dependencies = [
 
 [[package]]
 name = "nu-utils"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "crossterm_winapi",
  "lscolors",
@@ -2871,7 +2920,7 @@ dependencies = [
 
 [[package]]
 name = "nu_plugin_example"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "nu-plugin",
  "nu-protocol",
@@ -2879,7 +2928,7 @@ dependencies = [
 
 [[package]]
 name = "nu_plugin_gstat"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "git2",
  "nu-engine",
@@ -2889,7 +2938,7 @@ dependencies = [
 
 [[package]]
 name = "nu_plugin_inc"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "nu-plugin",
  "nu-protocol",
@@ -2898,7 +2947,7 @@ dependencies = [
 
 [[package]]
 name = "nu_plugin_query"
-version = "0.73.0"
+version = "0.74.0"
 dependencies = [
  "gjson",
  "nu-engine",
@@ -3089,6 +3138,16 @@ version = "11.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ab1bc2a289d34bd04a330323ac98a1b4bc82c9d9fcb1e66b63caa84da26b575"
 
+[[package]]
+name = "open"
+version = "3.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2078c0039e6a54a0c42c28faa984e115fb4c2d5bf2208f77d1961002df8576f8"
+dependencies = [
+ "pathdiff",
+ "windows-sys 0.42.0",
+]
+
 [[package]]
 name = "openssl"
 version = "0.10.42"
@@ -3144,6 +3203,12 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "os_str_bytes"
+version = "6.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b7820b9daea5457c9f21c69448905d723fbd21136ccf521748f23fd49e723ee"
+
 [[package]]
 name = "output_vt100"
 version = "0.1.3"
@@ -3198,7 +3263,7 @@ dependencies = [
  "libc",
  "redox_syscall",
  "smallvec",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -3640,14 +3705,14 @@ version = "0.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4a63d338dec139f56dacc692ca63ad35a6be6a797442479b55acd611d79e906"
 dependencies = [
- "nom 7.1.1",
+ "nom",
 ]
 
 [[package]]
 name = "powierza-coefficient"
-version = "1.0.1"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "64e2c03bca73af2a7a2c021a6b3b4991658b760b2e0a84e3e425a9c9eda2ba7f"
+checksum = "04123079750026568dff0e68efe1ca676f6686023f3bf7686b87dab661c0375b"
 
 [[package]]
 name = "ppv-lite86"
@@ -4252,7 +4317,7 @@ dependencies = [
  "io-lifetimes",
  "libc",
  "linux-raw-sys",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -4295,7 +4360,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "88d6731146462ea25d9244b2ed5fd1d716d25c52e4d54aa4fb0f3c4e9854dbe2"
 dependencies = [
  "lazy_static",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -4416,16 +4481,6 @@ dependencies = [
  "serde_derive",
 ]
 
-[[package]]
-name = "serde_cbor"
-version = "0.11.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2bef2ebfde456fb76bbcf9f59315333decc4fda0b2b44b420243c11e0f5ec1f5"
-dependencies = [
- "half",
- "serde",
-]
-
 [[package]]
 name = "serde_derive"
 version = "1.0.145"
@@ -4934,7 +4989,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8440c860cf79def6164e4a0a983bcc2305d82419177a0e0c71930d049e3ac5a1"
 dependencies = [
  "rustix",
- "windows-sys",
+ "windows-sys 0.36.1",
 ]
 
 [[package]]
@@ -4943,15 +4998,6 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "507e9898683b6c43a9aa55b64259b721b52ba226e0f3779137e50ad114a4c90b"
 
-[[package]]
-name = "textwrap"
-version = "0.11.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
-dependencies = [
- "unicode-width",
-]
-
 [[package]]
 name = "textwrap"
 version = "0.15.1"
@@ -4963,6 +5009,12 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "textwrap"
+version = "0.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "222a222a5bfe1bba4a77b45ec488a741b3cb8872e5e499451fd7d0129c9c7c3d"
+
 [[package]]
 name = "thin-slice"
 version = "0.1.1"
@@ -5065,9 +5117,9 @@ dependencies = [
 
 [[package]]
 name = "tokio"
-version = "1.21.2"
+version = "1.24.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9e03c497dc955702ba729190dc4aac6f2a0ce97f913e5b1b5912fc5039d9099"
+checksum = "1d9f76183f91ecfb55e1d7d5602bd1d979e38a3a522fe900241cf195624d67ae"
 dependencies = [
  "autocfg",
  "bytes",
@@ -5077,7 +5129,7 @@ dependencies = [
  "num_cpus",
  "pin-project-lite",
  "socket2",
- "winapi 0.3.9",
+ "windows-sys 0.42.0",
 ]
 
 [[package]]
@@ -5231,6 +5283,15 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "unicase"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.8"
@@ -5533,7 +5594,7 @@ dependencies = [
  "bstr",
  "const_format",
  "itertools",
- "nom 7.1.1",
+ "nom",
  "nom-supreme",
  "pori",
  "regex",
@@ -5634,6 +5695,21 @@ dependencies = [
  "windows_x86_64_msvc 0.36.1",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.42.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a3e1820f08b8513f676f7ab6c1f99ff312fb97b553d30ff4dd86f9f15728aa7"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc 0.42.0",
+ "windows_i686_gnu 0.42.0",
+ "windows_i686_msvc 0.42.0",
+ "windows_x86_64_gnu 0.42.0",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc 0.42.0",
+]
+
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.42.0"

Cargo.toml

@@ -3,14 +3,14 @@ authors = ["The Nushell Project Developers"]
 default-run = "nu"
 description = "A new type of shell"
 documentation = "https://www.nushell.sh/book/"
-edition = "2018"
+edition = "2021"
 exclude = ["images"]
 homepage = "https://www.nushell.sh"
 license = "MIT"
 name = "nu"
 repository = "https://github.com/nushell/nushell"
 rust-version = "1.60"
-version = "0.73.0"
+version = "0.74.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -45,20 +45,20 @@ ctrlc = "3.2.1"
 log = "0.4"
 miette = { version = "5.1.0", features = ["fancy-no-backtrace"] }
 nu-ansi-term = "0.46.0"
-nu-cli = { path="./crates/nu-cli", version = "0.73.0"  }
-nu-color-config = { path = "./crates/nu-color-config", version = "0.73.0"  }
-nu-command = { path="./crates/nu-command", version = "0.73.0"  }
-nu-engine = { path="./crates/nu-engine", version = "0.73.0"  }
-nu-json = { path="./crates/nu-json", version = "0.73.0"  }
-nu-parser = { path="./crates/nu-parser", version = "0.73.0"  }
-nu-path = { path="./crates/nu-path", version = "0.73.0"  }
-nu-plugin = { path = "./crates/nu-plugin", optional = true, version = "0.73.0"  }
-nu-pretty-hex = { path = "./crates/nu-pretty-hex", version = "0.73.0"  }
-nu-protocol = { path = "./crates/nu-protocol", version = "0.73.0"  }
-nu-system = { path = "./crates/nu-system", version = "0.73.0" }
-nu-table = { path = "./crates/nu-table", version = "0.73.0"  }
-nu-term-grid = { path = "./crates/nu-term-grid", version = "0.73.0"  }
-nu-utils = { path = "./crates/nu-utils", version = "0.73.0"  }
+nu-cli = { path="./crates/nu-cli", version = "0.74.0"  }
+nu-color-config = { path = "./crates/nu-color-config", version = "0.74.0"  }
+nu-command = { path="./crates/nu-command", version = "0.74.0"  }
+nu-engine = { path="./crates/nu-engine", version = "0.74.0"  }
+nu-json = { path="./crates/nu-json", version = "0.74.0"  }
+nu-parser = { path="./crates/nu-parser", version = "0.74.0"  }
+nu-path = { path="./crates/nu-path", version = "0.74.0"  }
+nu-plugin = { path = "./crates/nu-plugin", optional = true, version = "0.74.0"  }
+nu-pretty-hex = { path = "./crates/nu-pretty-hex", version = "0.74.0"  }
+nu-protocol = { path = "./crates/nu-protocol", version = "0.74.0"  }
+nu-system = { path = "./crates/nu-system", version = "0.74.0" }
+nu-table = { path = "./crates/nu-table", version = "0.74.0"  }
+nu-term-grid = { path = "./crates/nu-term-grid", version = "0.74.0"  }
+nu-utils = { path = "./crates/nu-utils", version = "0.74.0"  }
 reedline = { version = "0.14.0", features = ["bashisms", "sqlite"]}
 
 rayon = "1.5.1"
@@ -80,9 +80,10 @@ nix = { version = "0.25", default-features = false, features = ["signal", "proce
 atty = "0.2"
 
 [dev-dependencies]
-nu-test-support = { path="./crates/nu-test-support", version = "0.73.0"  }
+nu-test-support = { path="./crates/nu-test-support", version = "0.74.0"  }
 tempfile = "3.2.0"
 assert_cmd = "2.0.2"
+criterion = "0.4"
 pretty_assertions = "1.0.0"
 serial_test = "0.8.0"
 hamcrest2 = "0.3.0"
@@ -140,3 +141,18 @@ path = "src/main.rs"
 # changing versions in each sub-crate of the workspace is tedious
 [patch.crates-io]
 # reedline = { git = "https://github.com/nushell/reedline.git", branch = "main" }
+
+# Criterion benchmarking setup
+# Run all benchmarks with `cargo bench`
+# Run individual benchmarks like `cargo bench -- <regex>` e.g. `cargo bench -- parse`
+[[bench]]
+name = "encoder_benchmark"
+harness = false
+
+[[bench]]
+name = "eval_benchmark"
+harness = false
+
+[[bench]]
+name = "parser_benchmark"
+harness = false

Cross.toml

@@ -0,0 +1,9 @@
+# Configuration for cross-rs: https://github.com/cross-rs/cross
+# Run cross-rs like this:
+# cross build --target aarch64-unknown-linux-musl --release
+
+[target.aarch64-unknown-linux-gnu]
+dockerfile = "./docker/cross-rs/aarch64-unknown-linux-gnu.dockerfile"
+
+[target.aarch64-unknown-linux-musl]
+dockerfile = "./docker/cross-rs/aarch64-unknown-linux-musl.dockerfile"

README.md

@@ -47,7 +47,7 @@ brew install nushell
 winget install nushell
 ```
 
-To use `Nu` in Github Action, check [setup-nu](https://github.com/marketplace/actions/setup-nu) for more detail.
+To use `Nu` in GitHub Action, check [setup-nu](https://github.com/marketplace/actions/setup-nu) for more detail.
 
 Detailed installation instructions can be found in the [installation chapter of the book](https://www.nushell.sh/book/installation.html). Nu is available via many package managers:
 
@@ -174,6 +174,8 @@ These binaries interact with nu via a simple JSON-RPC protocol where the command
 If the plugin is a filter, data streams to it one element at a time, and it can stream data back in return via stdin/stdout.
 If the plugin is a sink, it is given the full vector of final data and is given free reign over stdin/stdout to use as it pleases.
 
+The [awesome-nu repo](https://github.com/nushell/awesome-nu#plugins) lists a variety of nu-plugins.
+
 ## Goals
 
 Nu adheres closely to a set of goals that make up its design philosophy. As features are added, they are checked against these goals.

benches/README.md

@@ -0,0 +1,7 @@
+# Criterion benchmarks
+
+These are benchmarks using [Criterion](https://github.com/bheisler/criterion.rs), a microbenchmarking tool for Rust.
+
+Run all benchmarks with `cargo bench`
+
+Or run individual benchmarks like `cargo bench -- <regex>` e.g. `cargo bench -- parse`

benches/eval_benchmark.rs

@@ -0,0 +1,42 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+use nu_cli::eval_source;
+use nu_protocol::{PipelineData, Span, Value};
+use nu_utils::{get_default_config, get_default_env};
+
+fn criterion_benchmark(c: &mut Criterion) {
+    c.bench_function("eval default_env.nu", |b| {
+        b.iter(|| {
+            let mut engine_state = nu_command::create_default_context();
+            let mut stack = nu_protocol::engine::Stack::new();
+            eval_source(
+                &mut engine_state,
+                &mut stack,
+                get_default_env().as_bytes(),
+                "default_env.nu",
+                PipelineData::empty(),
+            )
+        })
+    });
+
+    c.bench_function("eval default_config.nu", |b| {
+        b.iter(|| {
+            let mut engine_state = nu_command::create_default_context();
+            // parsing config.nu breaks without PWD set
+            engine_state.add_env_var(
+                "PWD".into(),
+                Value::string("/some/dir".to_string(), Span::test_data()),
+            );
+            let mut stack = nu_protocol::engine::Stack::new();
+            eval_source(
+                &mut engine_state,
+                &mut stack,
+                get_default_config().as_bytes(),
+                "default_config.nu",
+                PipelineData::empty(),
+            )
+        })
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

benches/parser_benchmark.rs

@@ -0,0 +1,34 @@
+use criterion::{criterion_group, criterion_main, BatchSize, Criterion};
+use nu_parser::parse;
+use nu_protocol::{Span, Value};
+use nu_utils::{get_default_config, get_default_env};
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let mut engine_state = nu_command::create_default_context();
+    // parsing config.nu breaks without PWD set
+    engine_state.add_env_var(
+        "PWD".into(),
+        Value::string("/some/dir".to_string(), Span::test_data()),
+    );
+
+    let default_env = get_default_env().as_bytes();
+    c.bench_function("parse_default_env_file", |b| {
+        b.iter_batched(
+            || nu_protocol::engine::StateWorkingSet::new(&engine_state),
+            |mut working_set| parse(&mut working_set, None, default_env, false, &[]),
+            BatchSize::SmallInput,
+        )
+    });
+
+    let default_config = get_default_config().as_bytes();
+    c.bench_function("parse_default_config_file", |b| {
+        b.iter_batched(
+            || nu_protocol::engine::StateWorkingSet::new(&engine_state),
+            |mut working_set| parse(&mut working_set, None, default_config, false, &[]),
+            BatchSize::SmallInput,
+        )
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

build-all-windows.cmd

@@ -5,7 +5,7 @@
 @echo.
 
 echo Building nushell.exe
-cargo build cargo build --features=dataframe
+cargo build --features=dataframe
 @echo.
 
 @cd crates\nu_plugin_example

crates/nu-cli/Cargo.toml

@@ -5,21 +5,21 @@ repository = "https://github.com/nushell/nushell/tree/main/crates/nu-cli"
 edition = "2021"
 license = "MIT"
 name = "nu-cli"
-version = "0.73.0"
+version = "0.74.0"
 
 [dev-dependencies]
-nu-test-support = { path="../nu-test-support", version = "0.73.0"  }
-nu-command = { path = "../nu-command", version = "0.73.0" }
+nu-test-support = { path="../nu-test-support", version = "0.74.0"  }
+nu-command = { path = "../nu-command", version = "0.74.0" }
 rstest = {version = "0.15.0", default-features = false}
 
 [dependencies]
-nu-engine = { path = "../nu-engine", version = "0.73.0"  }
-nu-path = { path = "../nu-path", version = "0.73.0"  }
-nu-parser = { path = "../nu-parser", version = "0.73.0"  }
-nu-protocol = { path = "../nu-protocol", version = "0.73.0"  }
-nu-utils = { path = "../nu-utils", version = "0.73.0"  }
+nu-engine = { path = "../nu-engine", version = "0.74.0"  }
+nu-path = { path = "../nu-path", version = "0.74.0"  }
+nu-parser = { path = "../nu-parser", version = "0.74.0"  }
+nu-protocol = { path = "../nu-protocol", version = "0.74.0"  }
+nu-utils = { path = "../nu-utils", version = "0.74.0"  }
 nu-ansi-term = "0.46.0"
-nu-color-config = { path = "../nu-color-config", version = "0.73.0"  }
+nu-color-config = { path = "../nu-color-config", version = "0.74.0"  }
 reedline = { version = "0.14.0", features = ["bashisms", "sqlite"]}
 
 atty = "0.2.14"

crates/nu-cli/src/completions/custom_completions.rs

@@ -66,6 +66,7 @@ impl Completer for CustomCompletion {
                 ],
                 redirect_stdout: true,
                 redirect_stderr: true,
+                parser_info: vec![],
             },
             PipelineData::empty(),
         );

crates/nu-cli/src/completions/file_completions.rs

@@ -146,6 +146,8 @@ pub fn file_path_completion(
                             || path.contains('"')
                             || path.contains(' ')
                             || path.contains('#')
+                            || path.contains('(')
+                            || path.contains(')')
                         {
                             path = format!("`{}`", path);
                         }

crates/nu-cli/src/completions/variable_completions.rs

@@ -9,6 +9,8 @@ use reedline::Suggestion;
 use std::str;
 use std::sync::Arc;
 
+use super::MatchAlgorithm;
+
 #[derive(Clone)]
 pub struct VariableCompletion {
     engine_state: Arc<EngineState>, // TODO: Is engine state necessary? It's already a part of working set in fetch()
@@ -73,10 +75,11 @@ impl Completer for VariableCompletion {
                         for suggestion in
                             nested_suggestions(val.clone(), nested_levels, current_span)
                         {
-                            if options
-                                .match_algorithm
-                                .matches_u8(suggestion.value.as_bytes(), &prefix)
-                            {
+                            if options.match_algorithm.matches_u8_insensitive(
+                                options.case_sensitive,
+                                suggestion.value.as_bytes(),
+                                &prefix,
+                            ) {
                                 output.push(suggestion);
                             }
                         }
@@ -86,10 +89,11 @@ impl Completer for VariableCompletion {
                 } else {
                     // No nesting provided, return all env vars
                     for env_var in env_vars {
-                        if options
-                            .match_algorithm
-                            .matches_u8(env_var.0.as_bytes(), &prefix)
-                        {
+                        if options.match_algorithm.matches_u8_insensitive(
+                            options.case_sensitive,
+                            env_var.0.as_bytes(),
+                            &prefix,
+                        ) {
                             output.push(Suggestion {
                                 value: env_var.0,
                                 description: None,
@@ -116,10 +120,11 @@ impl Completer for VariableCompletion {
                     for suggestion in
                         nested_suggestions(nuval, self.var_context.1.clone(), current_span)
                     {
-                        if options
-                            .match_algorithm
-                            .matches_u8(suggestion.value.as_bytes(), &prefix)
-                        {
+                        if options.match_algorithm.matches_u8_insensitive(
+                            options.case_sensitive,
+                            suggestion.value.as_bytes(),
+                            &prefix,
+                        ) {
                             output.push(suggestion);
                         }
                     }
@@ -138,10 +143,11 @@ impl Completer for VariableCompletion {
                     for suggestion in
                         nested_suggestions(value, self.var_context.1.clone(), current_span)
                     {
-                        if options
-                            .match_algorithm
-                            .matches_u8(suggestion.value.as_bytes(), &prefix)
-                        {
+                        if options.match_algorithm.matches_u8_insensitive(
+                            options.case_sensitive,
+                            suggestion.value.as_bytes(),
+                            &prefix,
+                        ) {
                             output.push(suggestion);
                         }
                     }
@@ -153,10 +159,11 @@ impl Completer for VariableCompletion {
 
         // Variable completion (e.g: $en<tab> to complete $env)
         for builtin in builtins {
-            if options
-                .match_algorithm
-                .matches_u8(builtin.as_bytes(), &prefix)
-            {
+            if options.match_algorithm.matches_u8_insensitive(
+                options.case_sensitive,
+                builtin.as_bytes(),
+                &prefix,
+            ) {
                 output.push(Suggestion {
                     value: builtin.to_string(),
                     description: None,
@@ -178,7 +185,11 @@ impl Completer for VariableCompletion {
                 .rev()
             {
                 for v in &overlay_frame.vars {
-                    if options.match_algorithm.matches_u8(v.0, &prefix) {
+                    if options.match_algorithm.matches_u8_insensitive(
+                        options.case_sensitive,
+                        v.0,
+                        &prefix,
+                    ) {
                         output.push(Suggestion {
                             value: String::from_utf8_lossy(v.0).to_string(),
                             description: None,
@@ -200,7 +211,11 @@ impl Completer for VariableCompletion {
             .rev()
         {
             for v in &overlay_frame.vars {
-                if options.match_algorithm.matches_u8(v.0, &prefix) {
+                if options.match_algorithm.matches_u8_insensitive(
+                    options.case_sensitive,
+                    v.0,
+                    &prefix,
+                ) {
                     output.push(Suggestion {
                         value: String::from_utf8_lossy(v.0).to_string(),
                         description: None,
@@ -281,3 +296,13 @@ fn recursive_value(val: Value, sublevels: Vec<Vec<u8>>) -> Value {
 
     val
 }
+
+impl MatchAlgorithm {
+    pub fn matches_u8_insensitive(&self, sensitive: bool, haystack: &[u8], needle: &[u8]) -> bool {
+        if sensitive {
+            self.matches_u8(haystack, needle)
+        } else {
+            self.matches_u8(&haystack.to_ascii_lowercase(), &needle.to_ascii_lowercase())
+        }
+    }
+}

crates/nu-cli/src/nu_highlight.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Value};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Type, Value};
 use reedline::Highlighter;
 
 #[derive(Clone)]
@@ -12,7 +12,9 @@ impl Command for NuHighlight {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("nu-highlight").category(Category::Strings)
+        Signature::build("nu-highlight")
+            .category(Category::Strings)
+            .input_output_types(vec![(Type::String, Type::String)])
     }
 
     fn usage(&self) -> &str {

crates/nu-cli/src/print.rs

@@ -2,7 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Type,
+    Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +16,7 @@ impl Command for Print {
 
     fn signature(&self) -> Signature {
         Signature::build("print")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .rest("rest", SyntaxShape::Any, "the values to print")
             .switch(
                 "no-newline",

crates/nu-cli/src/prompt_update.rs

@@ -1,6 +1,6 @@
 use crate::util::report_error;
 use crate::NushellPrompt;
-use log::info;
+use log::trace;
 use nu_engine::eval_subexpression;
 use nu_protocol::{
     engine::{EngineState, Stack, StateWorkingSet},
@@ -39,7 +39,7 @@ fn get_prompt_string(
                 // Use eval_subexpression to force a redirection of output, so we can use everything in prompt
                 let ret_val =
                     eval_subexpression(engine_state, &mut stack, block, PipelineData::empty());
-                info!(
+                trace!(
                     "get_prompt_string (block) {}:{}:{}",
                     file!(),
                     line!(),
@@ -59,7 +59,7 @@ fn get_prompt_string(
                 let block = engine_state.get_block(block_id);
                 // Use eval_subexpression to force a redirection of output, so we can use everything in prompt
                 let ret_val = eval_subexpression(engine_state, stack, block, PipelineData::empty());
-                info!(
+                trace!(
                     "get_prompt_string (block) {}:{}:{}",
                     file!(),
                     line!(),
@@ -148,7 +148,7 @@ pub(crate) fn update_prompt<'prompt>(
     );
 
     let ret_val = nu_prompt as &dyn Prompt;
-    info!("update_prompt {}:{}:{}", file!(), line!(), column!());
+    trace!("update_prompt {}:{}:{}", file!(), line!(), column!());
 
     ret_val
 }

crates/nu-cli/src/reedline_config.rs

@@ -7,8 +7,7 @@ use nu_parser::parse;
 use nu_protocol::{
     create_menus,
     engine::{EngineState, Stack, StateWorkingSet},
-    extract_value, Config, IntoPipelineData, ParsedKeybinding, ParsedMenu, PipelineData,
-    ShellError, Span, Value,
+    extract_value, Config, ParsedKeybinding, ParsedMenu, PipelineData, ShellError, Span, Value,
 };
 use reedline::{
     default_emacs_keybindings, default_vi_insert_keybindings, default_vi_normal_keybindings,
@@ -110,7 +109,7 @@ pub(crate) fn add_menus(
             };
 
             let mut temp_stack = Stack::new();
-            let input = Value::nothing(Span::test_data()).into_pipeline_data();
+            let input = PipelineData::Empty;
             let res = eval_block(&engine_state, &mut temp_stack, &block, input, false, false)?;
 
             if let PipelineData::Value(value, None) = res {
@@ -680,9 +679,9 @@ fn add_parsed_keybinding(
             let fn_num: u8 = c[1..]
                 .parse()
                 .ok()
-                .filter(|num| matches!(num, 1..=12))
+                .filter(|num| matches!(num, 1..=20))
                 .ok_or(ShellError::UnsupportedConfigValue(
-                    "(f1|f2|...|f12)".to_string(),
+                    "(f1|f2|...|f20)".to_string(),
                     format!("unknown function key: {}", c),
                     keybinding.keycode.span()?,
                 ))?;
@@ -990,7 +989,7 @@ mod test {
     #[test]
     fn test_send_event() {
         let cols = vec!["send".to_string()];
-        let vals = vec![Value::string("Enter", Span::test_data())];
+        let vals = vec![Value::test_string("Enter")];
 
         let span = Span::test_data();
         let b = EventType::try_from_columns(&cols, &vals, &span).unwrap();
@@ -1010,7 +1009,7 @@ mod test {
     #[test]
     fn test_edit_event() {
         let cols = vec!["edit".to_string()];
-        let vals = vec![Value::string("Clear", Span::test_data())];
+        let vals = vec![Value::test_string("Clear")];
 
         let span = Span::test_data();
         let b = EventType::try_from_columns(&cols, &vals, &span).unwrap();
@@ -1034,8 +1033,8 @@ mod test {
     fn test_send_menu() {
         let cols = vec!["send".to_string(), "name".to_string()];
         let vals = vec![
-            Value::string("Menu", Span::test_data()),
-            Value::string("history_menu", Span::test_data()),
+            Value::test_string("Menu"),
+            Value::test_string("history_menu"),
         ];
 
         let span = Span::test_data();
@@ -1061,8 +1060,8 @@ mod test {
         // Menu event
         let cols = vec!["send".to_string(), "name".to_string()];
         let vals = vec![
-            Value::string("Menu", Span::test_data()),
-            Value::string("history_menu", Span::test_data()),
+            Value::test_string("Menu"),
+            Value::test_string("history_menu"),
         ];
 
         let menu_event = Value::Record {
@@ -1073,7 +1072,7 @@ mod test {
 
         // Enter event
         let cols = vec!["send".to_string()];
-        let vals = vec![Value::string("Enter", Span::test_data())];
+        let vals = vec![Value::test_string("Enter")];
 
         let enter_event = Value::Record {
             cols,
@@ -1114,8 +1113,8 @@ mod test {
         // Menu event
         let cols = vec!["send".to_string(), "name".to_string()];
         let vals = vec![
-            Value::string("Menu", Span::test_data()),
-            Value::string("history_menu", Span::test_data()),
+            Value::test_string("Menu"),
+            Value::test_string("history_menu"),
         ];
 
         let menu_event = Value::Record {
@@ -1126,7 +1125,7 @@ mod test {
 
         // Enter event
         let cols = vec!["send".to_string()];
-        let vals = vec![Value::string("Enter", Span::test_data())];
+        let vals = vec![Value::test_string("Enter")];
 
         let enter_event = Value::Record {
             cols,
@@ -1154,7 +1153,7 @@ mod test {
     #[test]
     fn test_error() {
         let cols = vec!["not_exist".to_string()];
-        let vals = vec![Value::string("Enter", Span::test_data())];
+        let vals = vec![Value::test_string("Enter")];
 
         let span = Span::test_data();
         let b = EventType::try_from_columns(&cols, &vals, &span);

crates/nu-cli/src/repl.rs

@@ -639,7 +639,7 @@ pub fn eval_string_with_input(
         false,
         true,
     )
-    .map(|x| x.into_value(Span::test_data()))
+    .map(|x| x.into_value(Span::unknown()))
 }
 
 pub fn get_command_finished_marker(stack: &Stack, engine_state: &EngineState) -> String {
@@ -734,60 +734,63 @@ pub fn eval_hook(
             }
         }
         Value::Record { .. } => {
-            let do_run_hook =
-                if let Ok(condition) = value.clone().follow_cell_path(&[condition_path], false) {
-                    match condition {
-                        Value::Block {
-                            val: block_id,
-                            span: block_span,
-                            ..
-                        }
-                        | Value::Closure {
-                            val: block_id,
-                            span: block_span,
-                            ..
-                        } => {
-                            match run_hook_block(
-                                engine_state,
-                                stack,
-                                block_id,
-                                None,
-                                arguments.clone(),
-                                block_span,
-                            ) {
-                                Ok(pipeline_data) => {
-                                    if let PipelineData::Value(Value::Bool { val, .. }, ..) =
-                                        pipeline_data
-                                    {
-                                        val
-                                    } else {
-                                        return Err(ShellError::UnsupportedConfigValue(
-                                            "boolean output".to_string(),
-                                            "other PipelineData variant".to_string(),
-                                            block_span,
-                                        ));
-                                    }
-                                }
-                                Err(err) => {
-                                    return Err(err);
+            let do_run_hook = if let Ok(condition) =
+                value
+                    .clone()
+                    .follow_cell_path(&[condition_path], false, false)
+            {
+                match condition {
+                    Value::Block {
+                        val: block_id,
+                        span: block_span,
+                        ..
+                    }
+                    | Value::Closure {
+                        val: block_id,
+                        span: block_span,
+                        ..
+                    } => {
+                        match run_hook_block(
+                            engine_state,
+                            stack,
+                            block_id,
+                            None,
+                            arguments.clone(),
+                            block_span,
+                        ) {
+                            Ok(pipeline_data) => {
+                                if let PipelineData::Value(Value::Bool { val, .. }, ..) =
+                                    pipeline_data
+                                {
+                                    val
+                                } else {
+                                    return Err(ShellError::UnsupportedConfigValue(
+                                        "boolean output".to_string(),
+                                        "other PipelineData variant".to_string(),
+                                        block_span,
+                                    ));
                                 }
                             }
-                        }
-                        other => {
-                            return Err(ShellError::UnsupportedConfigValue(
-                                "block".to_string(),
-                                format!("{}", other.get_type()),
-                                other.span()?,
-                            ));
+                            Err(err) => {
+                                return Err(err);
+                            }
                         }
                     }
-                } else {
-                    // always run the hook
-                    true
-                };
+                    other => {
+                        return Err(ShellError::UnsupportedConfigValue(
+                            "block".to_string(),
+                            format!("{}", other.get_type()),
+                            other.span()?,
+                        ));
+                    }
+                }
+            } else {
+                // always run the hook
+                true
+            };
 
             if do_run_hook {
-                match value.clone().follow_cell_path(&[code_path], false)? {
+                match value.clone().follow_cell_path(&[code_path], false, false)? {
                     Value::String {
                         val,
                         span: source_span,

crates/nu-cli/src/syntax_highlight.rs

@@ -352,6 +352,7 @@ fn find_matching_block_end_in_expr(
                     let opt_expr = match arg {
                         Argument::Named((_, _, opt_expr)) => opt_expr.as_ref(),
                         Argument::Positional(inner_expr) => Some(inner_expr),
+                        Argument::Unknown(inner_expr) => Some(inner_expr),
                     };
 
                     if let Some(inner_expr) = opt_expr {

crates/nu-cli/tests/completions.rs

@@ -34,6 +34,26 @@ fn completer_strings() -> NuCompleter {
     NuCompleter::new(std::sync::Arc::new(engine), stack)
 }
 
+#[fixture]
+fn extern_completer() -> NuCompleter {
+    // Create a new engine
+    let (dir, _, mut engine, mut stack) = new_engine();
+
+    // Add record value as example
+    let record = r#"
+        def animals [] { [ "cat", "dog", "eel" ] }
+        extern spam [
+            animal: string@animals
+            --foo (-f): string@animals
+            -b: string@animals
+        ]
+    "#;
+    assert!(support::merge_input(record.as_bytes(), &mut engine, &mut stack, dir).is_ok());
+
+    // Instantiate a new completer
+    NuCompleter::new(std::sync::Arc::new(engine), stack)
+}
+
 #[test]
 fn variables_dollar_sign_with_varialblecompletion() {
     let (_, _, engine, stack) = new_engine();
@@ -89,7 +109,7 @@ fn dotnu_completions() {
     // Create a new engine
     let (_, _, engine, stack) = new_engine();
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
 
     // Test source completion
@@ -149,7 +169,7 @@ fn file_completions() {
     // Create a new engine
     let (dir, dir_str, engine, stack) = new_engine();
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
 
     // Test completions for the current folder
@@ -424,6 +444,7 @@ fn file_completion_quoted() {
         "`te st.txt`".to_string(),
         "`te#st.txt`".to_string(),
         "`te'st.txt`".to_string(),
+        "`te(st).txt`".to_string(),
     ];
 
     match_suggestions(expected_paths, suggestions)
@@ -434,12 +455,12 @@ fn flag_completions() {
     // Create a new engine
     let (_, _, engine, stack) = new_engine();
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
     // Test completions for the 'ls' flags
     let suggestions = completer.complete("ls -", 4);
 
-    assert_eq!(14, suggestions.len());
+    assert_eq!(16, suggestions.len());
 
     let expected: Vec<String> = vec![
         "--all".into(),
@@ -448,6 +469,7 @@ fn flag_completions() {
         "--full-paths".into(),
         "--help".into(),
         "--long".into(),
+        "--mime-type".into(),
         "--short-names".into(),
         "-D".into(),
         "-a".into(),
@@ -455,6 +477,7 @@ fn flag_completions() {
         "-f".into(),
         "-h".into(),
         "-l".into(),
+        "-m".into(),
         "-s".into(),
     ];
 
@@ -467,7 +490,7 @@ fn folder_with_directorycompletions() {
     // Create a new engine
     let (dir, dir_str, engine, stack) = new_engine();
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
 
     // Test completions for the current folder
@@ -495,7 +518,7 @@ fn variables_completions() {
     let record = "let actor = { name: 'Tom Hardy', age: 44 }";
     assert!(support::merge_input(record.as_bytes(), &mut engine, &mut stack, dir).is_ok());
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
 
     // Test completions for $nu
@@ -652,7 +675,7 @@ fn run_external_completion(block: &str, input: &str) -> Vec<Suggestion> {
     config.external_completer = Some(latest_block_id);
     engine_state.set_config(&config);
 
-    // Instatiate a new completer
+    // Instantiate a new completer
     let mut completer = NuCompleter::new(std::sync::Arc::new(engine_state), stack);
 
     completer.complete(input, input.len())
@@ -750,3 +773,45 @@ fn filecompletions_triggers_after_cursor() {
 
     match_suggestions(expected_paths, suggestions);
 }
+
+#[rstest]
+fn extern_custom_completion_positional(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam ", 5);
+    let expected: Vec<String> = vec!["cat".into(), "dog".into(), "eel".into()];
+    match_suggestions(expected, suggestions);
+}
+
+#[rstest]
+fn extern_custom_completion_long_flag_1(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam --foo=", 11);
+    let expected: Vec<String> = vec!["cat".into(), "dog".into(), "eel".into()];
+    match_suggestions(expected, suggestions);
+}
+
+#[rstest]
+fn extern_custom_completion_long_flag_2(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam --foo ", 11);
+    let expected: Vec<String> = vec!["cat".into(), "dog".into(), "eel".into()];
+    match_suggestions(expected, suggestions);
+}
+
+#[rstest]
+fn extern_custom_completion_long_flag_short(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam -f ", 8);
+    let expected: Vec<String> = vec!["cat".into(), "dog".into(), "eel".into()];
+    match_suggestions(expected, suggestions);
+}
+
+#[rstest]
+fn extern_custom_completion_short_flag(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam -b ", 8);
+    let expected: Vec<String> = vec!["cat".into(), "dog".into(), "eel".into()];
+    match_suggestions(expected, suggestions);
+}
+
+#[rstest]
+fn extern_complete_flags(mut extern_completer: NuCompleter) {
+    let suggestions = extern_completer.complete("spam -", 6);
+    let expected: Vec<String> = vec!["--foo".into(), "-b".into(), "-f".into()];
+    match_suggestions(expected, suggestions);
+}

crates/nu-color-config/Cargo.toml

@@ -5,18 +5,18 @@ repository = "https://github.com/nushell/nushell/tree/main/crates/nu-color-confi
 edition = "2021"
 license = "MIT"
 name = "nu-color-config"
-version = "0.73.0"
+version = "0.74.0"
 
 [dependencies]
 serde = { version="1.0.123", features=["derive"] }
 # used only for text_style Alignments
 tabled = { version = "0.10.0", features = ["color"], default-features = false }
 
-nu-protocol = { path = "../nu-protocol", version = "0.73.0"  }
+nu-protocol = { path = "../nu-protocol", version = "0.74.0"  }
 nu-ansi-term = "0.46.0"
-nu-utils = { path = "../nu-utils", version = "0.73.0" }
-nu-engine = { path = "../nu-engine", version = "0.73.0" }
-nu-json = { path="../nu-json", version = "0.73.0"  }
+nu-utils = { path = "../nu-utils", version = "0.74.0" }
+nu-engine = { path = "../nu-engine", version = "0.74.0" }
+nu-json = { path="../nu-json", version = "0.74.0"  }
 
 [dev-dependencies]
-nu-test-support = { path="../nu-test-support", version = "0.73.0"  }
+nu-test-support = { path="../nu-test-support", version = "0.74.0"  }

crates/nu-color-config/src/shape_color.rs

@@ -1,45 +1,56 @@
-use crate::color_config::lookup_ansi_color_style;
+use crate::{color_config::lookup_ansi_color_style, color_record_to_nustyle};
 use nu_ansi_term::{Color, Style};
-use nu_protocol::Config;
+use nu_protocol::{Config, Value};
+
+// The default colors for shapes, used when there is no config for them.
+pub fn default_shape_color(shape: String) -> Style {
+    match shape.as_ref() {
+        "shape_and" => Style::new().fg(Color::Purple).bold(),
+        "shape_binary" => Style::new().fg(Color::Purple).bold(),
+        "shape_block" => Style::new().fg(Color::Blue).bold(),
+        "shape_bool" => Style::new().fg(Color::LightCyan),
+        "shape_custom" => Style::new().fg(Color::Green),
+        "shape_datetime" => Style::new().fg(Color::Cyan).bold(),
+        "shape_directory" => Style::new().fg(Color::Cyan),
+        "shape_external" => Style::new().fg(Color::Cyan),
+        "shape_externalarg" => Style::new().fg(Color::Green).bold(),
+        "shape_filepath" => Style::new().fg(Color::Cyan),
+        "shape_flag" => Style::new().fg(Color::Blue).bold(),
+        "shape_float" => Style::new().fg(Color::Purple).bold(),
+        "shape_garbage" => Style::new().fg(Color::White).on(Color::Red).bold(),
+        "shape_globpattern" => Style::new().fg(Color::Cyan).bold(),
+        "shape_int" => Style::new().fg(Color::Purple).bold(),
+        "shape_internalcall" => Style::new().fg(Color::Cyan).bold(),
+        "shape_list" => Style::new().fg(Color::Cyan).bold(),
+        "shape_literal" => Style::new().fg(Color::Blue),
+        "shape_nothing" => Style::new().fg(Color::LightCyan),
+        "shape_operator" => Style::new().fg(Color::Yellow),
+        "shape_or" => Style::new().fg(Color::Purple).bold(),
+        "shape_pipe" => Style::new().fg(Color::Purple).bold(),
+        "shape_range" => Style::new().fg(Color::Yellow).bold(),
+        "shape_record" => Style::new().fg(Color::Cyan).bold(),
+        "shape_redirection" => Style::new().fg(Color::Purple).bold(),
+        "shape_signature" => Style::new().fg(Color::Green).bold(),
+        "shape_string" => Style::new().fg(Color::Green),
+        "shape_string_interpolation" => Style::new().fg(Color::Cyan).bold(),
+        "shape_table" => Style::new().fg(Color::Blue).bold(),
+        "shape_variable" => Style::new().fg(Color::Purple),
+        _ => Style::default(),
+    }
+}
 
 pub fn get_shape_color(shape: String, conf: &Config) -> Style {
     match conf.color_config.get(shape.as_str()) {
-        Some(int_color) => match int_color.as_string() {
-            Ok(int_color) => lookup_ansi_color_style(&int_color),
-            Err(_) => Style::default(),
-        },
-        None => match shape.as_ref() {
-            "shape_and" => Style::new().fg(Color::Purple).bold(),
-            "shape_binary" => Style::new().fg(Color::Purple).bold(),
-            "shape_block" => Style::new().fg(Color::Blue).bold(),
-            "shape_bool" => Style::new().fg(Color::LightCyan),
-            "shape_custom" => Style::new().fg(Color::Green),
-            "shape_datetime" => Style::new().fg(Color::Cyan).bold(),
-            "shape_directory" => Style::new().fg(Color::Cyan),
-            "shape_external" => Style::new().fg(Color::Cyan),
-            "shape_externalarg" => Style::new().fg(Color::Green).bold(),
-            "shape_filepath" => Style::new().fg(Color::Cyan),
-            "shape_flag" => Style::new().fg(Color::Blue).bold(),
-            "shape_float" => Style::new().fg(Color::Purple).bold(),
-            "shape_garbage" => Style::new().fg(Color::White).on(Color::Red).bold(),
-            "shape_globpattern" => Style::new().fg(Color::Cyan).bold(),
-            "shape_int" => Style::new().fg(Color::Purple).bold(),
-            "shape_internalcall" => Style::new().fg(Color::Cyan).bold(),
-            "shape_list" => Style::new().fg(Color::Cyan).bold(),
-            "shape_literal" => Style::new().fg(Color::Blue),
-            "shape_nothing" => Style::new().fg(Color::LightCyan),
-            "shape_operator" => Style::new().fg(Color::Yellow),
-            "shape_or" => Style::new().fg(Color::Purple).bold(),
-            "shape_pipe" => Style::new().fg(Color::Purple).bold(),
-            "shape_range" => Style::new().fg(Color::Yellow).bold(),
-            "shape_record" => Style::new().fg(Color::Cyan).bold(),
-            "shape_redirection" => Style::new().fg(Color::Purple).bold(),
-            "shape_signature" => Style::new().fg(Color::Green).bold(),
-            "shape_string" => Style::new().fg(Color::Green),
-            "shape_string_interpolation" => Style::new().fg(Color::Cyan).bold(),
-            "shape_table" => Style::new().fg(Color::Blue).bold(),
-            "shape_variable" => Style::new().fg(Color::Purple),
-            _ => Style::default(),
-        },
+        Some(int_color) => {
+            // Shapes do not use color_config closures, currently.
+            match int_color {
+                Value::Record { .. } => color_record_to_nustyle(int_color),
+                Value::String { val, .. } => lookup_ansi_color_style(val),
+                // Defer to the default in the event of incorrect types being given
+                // (i.e. treat null, etc. as the value being unset)
+                _ => default_shape_color(shape),
+            }
+        }
+        None => default_shape_color(shape),
     }
 }

crates/nu-color-config/src/style_computer.rs

@@ -126,7 +126,7 @@ impl<'a> StyleComputer<'a> {
 
             Value::Filesize { .. } => TextStyle::with_style(AlignmentHorizontal::Right, s),
 
-            Value::Duration { .. } => TextStyle::with_style(AlignmentHorizontal::Left, s),
+            Value::Duration { .. } => TextStyle::with_style(AlignmentHorizontal::Right, s),
 
             Value::Date { .. } => TextStyle::with_style(AlignmentHorizontal::Left, s),
 

crates/nu-command/Cargo.toml

@@ -5,25 +5,25 @@ repository = "https://github.com/nushell/nushell/tree/main/crates/nu-command"
 edition = "2021"
 license = "MIT"
 name = "nu-command"
-version = "0.73.0"
+version = "0.74.0"
 build = "build.rs"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-nu-color-config = { path = "../nu-color-config", version = "0.73.0"  }
-nu-engine = { path = "../nu-engine", version = "0.73.0"  }
-nu-glob = { path = "../nu-glob", version = "0.73.0" }
-nu-json = { path = "../nu-json", version = "0.73.0"  }
-nu-parser = { path = "../nu-parser", version = "0.73.0"  }
-nu-path = { path = "../nu-path", version = "0.73.0"  }
-nu-pretty-hex = { path = "../nu-pretty-hex", version = "0.73.0"  }
-nu-protocol = { path = "../nu-protocol", version = "0.73.0"  }
-nu-system = { path = "../nu-system", version = "0.73.0"  }
-nu-table = { path = "../nu-table", version = "0.73.0"  }
-nu-term-grid = { path = "../nu-term-grid", version = "0.73.0"  }
-nu-utils = { path = "../nu-utils", version = "0.73.0" }
-nu-explore = { path = "../nu-explore", version = "0.73.0" }
+nu-color-config = { path = "../nu-color-config", version = "0.74.0"  }
+nu-engine = { path = "../nu-engine", version = "0.74.0"  }
+nu-glob = { path = "../nu-glob", version = "0.74.0" }
+nu-json = { path = "../nu-json", version = "0.74.0"  }
+nu-parser = { path = "../nu-parser", version = "0.74.0"  }
+nu-path = { path = "../nu-path", version = "0.74.0"  }
+nu-pretty-hex = { path = "../nu-pretty-hex", version = "0.74.0"  }
+nu-protocol = { path = "../nu-protocol", version = "0.74.0"  }
+nu-system = { path = "../nu-system", version = "0.74.0"  }
+nu-table = { path = "../nu-table", version = "0.74.0"  }
+nu-term-grid = { path = "../nu-term-grid", version = "0.74.0"  }
+nu-utils = { path = "../nu-utils", version = "0.74.0" }
+nu-explore = { path = "../nu-explore", version = "0.74.0" }
 nu-ansi-term = "0.46.0"
 num-format = { version = "0.4.3" }
 
@@ -57,14 +57,15 @@ itertools = "0.10.0"
 log = "0.4.14"
 lscolors = { version = "0.12.0", features = ["crossterm"], default-features = false }
 md5 = { package = "md-5", version = "0.10.0" }
-meval = "0.2.0"
 mime = "0.3.16"
+mime_guess = "2.0.4"
 notify = "4.0.17"
 num = { version = "0.4.0", optional = true }
 num-traits = "0.2.14"
 once_cell = "1.0"
+open = "3.2.0"
 pathdiff = "0.2.1"
-powierza-coefficient = "1.0.1"
+powierza-coefficient = "1.0.2"
 quick-xml = "0.25"
 rand = "0.8"
 rayon = "1.5.1"
@@ -87,6 +88,7 @@ titlecase = "2.0.0"
 toml = "0.5.8"
 unicode-segmentation = "1.8.0"
 url = "2.2.1"
+percent-encoding = "2.2.0"
 uuid = { version = "1.1.2", features = ["v4"] }
 which = { version = "4.3.0", optional = true }
 reedline = { version = "0.14.0", features = ["bashisms", "sqlite"]}
@@ -156,7 +158,7 @@ sqlite = ["rusqlite"] # TODO: given that rusqlite is included in reedline, shoul
 shadow-rs = { version = "0.16.1", default-features = false }
 
 [dev-dependencies]
-nu-test-support = { path = "../nu-test-support", version = "0.73.0"  }
+nu-test-support = { path = "../nu-test-support", version = "0.74.0"  }
 
 hamcrest2 = "0.3.0"
 dirs-next = "2.0.0"

crates/nu-command/src/bits/and.rs

@@ -43,6 +43,10 @@ impl Command for SubCommand {
         let head = call.head;
         let target: i64 = call.req(engine_state, stack, 0)?;
 
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, target, head),
             engine_state.ctrlc.clone(),
@@ -54,7 +58,7 @@ impl Command for SubCommand {
             Example {
                 description: "Apply bits and to two numbers",
                 example: "2 | bits and 2",
-                result: Some(Value::int(2, Span::test_data())),
+                result: Some(Value::test_int(2)),
             },
             Example {
                 description: "Apply logical and to a list of numbers",
@@ -74,13 +78,15 @@ fn operate(value: Value, target: i64, head: Span) -> Value {
             val: val & target,
             span,
         },
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/bits_.rs

@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, Signature, Value,
+    Category, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,13 +14,19 @@ impl Command for Bits {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("bits").category(Category::Bits)
+        Signature::build("bits")
+            .category(Category::Bits)
+            .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
     fn usage(&self) -> &str {
         "Various commands for working with bits"
     }
 
+    fn extra_usage(&self) -> &str {
+        "You must use one of the following subcommands. Using this command as-is will only produce this help message."
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,
@@ -41,15 +47,3 @@ impl Command for Bits {
         .into_pipeline_data())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use crate::Bits;
-
-    #[test]
-    fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(Bits {})
-    }
-}

crates/nu-command/src/bits/not.rs

@@ -56,11 +56,17 @@ impl Command for SubCommand {
             if let Some(val) = number_bytes {
                 return Err(ShellError::UnsupportedInput(
                     "Only 1, 2, 4, 8, or 'auto' bytes are supported as word sizes".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     val.span,
                 ));
             }
         }
 
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, head, signed, bytes_len),
             engine_state.ctrlc.clone(),
@@ -140,14 +146,17 @@ fn operate(value: Value, head: Span, signed: bool, number_size: NumberBytes) ->
                 Value::Int { val: out_val, span }
             }
         }
-        other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only numerical values are supported, input type: {:?}",
-                    other.get_type()
+        other => match other {
+            // Propagate errors inside the value
+            Value::Error { .. } => other,
+            _ => Value::Error {
+                error: ShellError::OnlySupportsThisInputType(
+                    "numeric".into(),
+                    other.get_type().to_string(),
+                    head,
+                    other.expect_span(),
                 ),
-                other.span().unwrap_or(head),
-            ),
+            },
         },
     }
 }

crates/nu-command/src/bits/or.rs

@@ -43,6 +43,10 @@ impl Command for SubCommand {
         let head = call.head;
         let target: i64 = call.req(engine_state, stack, 0)?;
 
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, target, head),
             engine_state.ctrlc.clone(),
@@ -54,7 +58,7 @@ impl Command for SubCommand {
             Example {
                 description: "Apply bits or to two numbers",
                 example: "2 | bits or 6",
-                result: Some(Value::int(6, Span::test_data())),
+                result: Some(Value::test_int(6)),
             },
             Example {
                 description: "Apply logical or to a list of numbers",
@@ -74,13 +78,15 @@ fn operate(value: Value, target: i64, head: Span) -> Value {
             val: val | target,
             span,
         },
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/rotate_left.rs

@@ -60,11 +60,16 @@ impl Command for SubCommand {
             if let Some(val) = number_bytes {
                 return Err(ShellError::UnsupportedInput(
                     "Only 1, 2, 4, 8, or 'auto' bytes are supported as word sizes".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     val.span,
                 ));
             }
         }
-
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, bits, head, signed, bytes_len),
             engine_state.ctrlc.clone(),
@@ -76,7 +81,7 @@ impl Command for SubCommand {
             Example {
                 description: "Rotate left a number with 2 bits",
                 example: "17 | bits rol 2",
-                result: Some(Value::int(68, Span::test_data())),
+                result: Some(Value::test_int(68)),
             },
             Example {
                 description: "Rotate left a list of numbers with 2 bits",
@@ -130,13 +135,15 @@ fn operate(value: Value, bits: usize, head: Span, signed: bool, number_size: Num
                 SignedEight => get_rotate_left(val as i64, bits, span),
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/rotate_right.rs

@@ -60,11 +60,16 @@ impl Command for SubCommand {
             if let Some(val) = number_bytes {
                 return Err(ShellError::UnsupportedInput(
                     "Only 1, 2, 4, 8, or 'auto' bytes are supported as word sizes".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     val.span,
                 ));
             }
         }
-
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, bits, head, signed, bytes_len),
             engine_state.ctrlc.clone(),
@@ -76,7 +81,7 @@ impl Command for SubCommand {
             Example {
                 description: "Rotate right a number with 60 bits",
                 example: "17 | bits ror 60",
-                result: Some(Value::int(272, Span::test_data())),
+                result: Some(Value::test_int(272)),
             },
             Example {
                 description: "Rotate right a list of numbers of one byte",
@@ -134,13 +139,15 @@ fn operate(value: Value, bits: usize, head: Span, signed: bool, number_size: Num
                 SignedEight => get_rotate_right(val as i64, bits, span),
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/shift_left.rs

@@ -60,11 +60,16 @@ impl Command for SubCommand {
             if let Some(val) = number_bytes {
                 return Err(ShellError::UnsupportedInput(
                     "Only 1, 2, 4, 8, or 'auto' bytes are supported as word sizes".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     val.span,
                 ));
             }
         }
-
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, bits, head, signed, bytes_len),
             engine_state.ctrlc.clone(),
@@ -76,17 +81,17 @@ impl Command for SubCommand {
             Example {
                 description: "Shift left a number by 7 bits",
                 example: "2 | bits shl 7",
-                result: Some(Value::int(256, Span::test_data())),
+                result: Some(Value::test_int(256)),
             },
             Example {
                 description: "Shift left a number with 1 byte by 7 bits",
                 example: "2 | bits shl 7 -n 1",
-                result: Some(Value::int(0, Span::test_data())),
+                result: Some(Value::test_int(0)),
             },
             Example {
                 description: "Shift left a signed number by 1 bit",
                 example: "0x7F | bits shl 1 -s",
-                result: Some(Value::int(254, Span::test_data())),
+                result: Some(Value::test_int(254)),
             },
             Example {
                 description: "Shift left a list of numbers",
@@ -156,13 +161,15 @@ fn operate(value: Value, bits: usize, head: Span, signed: bool, number_size: Num
                 SignedEight => get_shift_left(val as i64, bits, span),
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/shift_right.rs

@@ -60,11 +60,16 @@ impl Command for SubCommand {
             if let Some(val) = number_bytes {
                 return Err(ShellError::UnsupportedInput(
                     "Only 1, 2, 4, 8, or 'auto' bytes are supported as word sizes".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     val.span,
                 ));
             }
         }
-
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, bits, head, signed, bytes_len),
             engine_state.ctrlc.clone(),
@@ -76,7 +81,7 @@ impl Command for SubCommand {
             Example {
                 description: "Shift right a number with 2 bits",
                 example: "8 | bits shr 2",
-                result: Some(Value::int(2, Span::test_data())),
+                result: Some(Value::test_int(2)),
             },
             Example {
                 description: "Shift right a list of numbers",
@@ -146,13 +151,15 @@ fn operate(value: Value, bits: usize, head: Span, signed: bool, number_size: Num
                 SignedEight => get_shift_right(val as i64, bits, span),
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bits/xor.rs

@@ -42,7 +42,10 @@ impl Command for SubCommand {
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
         let head = call.head;
         let target: i64 = call.req(engine_state, stack, 0)?;
-
+        // This doesn't match explicit nulls
+        if matches!(input, PipelineData::Empty) {
+            return Err(ShellError::PipelineEmpty(head));
+        }
         input.map(
             move |value| operate(value, target, head),
             engine_state.ctrlc.clone(),
@@ -54,7 +57,7 @@ impl Command for SubCommand {
             Example {
                 description: "Apply bits xor to two numbers",
                 example: "2 | bits xor 2",
-                result: Some(Value::int(0, Span::test_data())),
+                result: Some(Value::test_int(0)),
             },
             Example {
                 description: "Apply logical xor to a list of numbers",
@@ -74,13 +77,15 @@ fn operate(value: Value, target: i64, head: Span) -> Value {
             val: val ^ target,
             span,
         },
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => value,
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Only integer values are supported, input type: {:?}",
-                    other.get_type()
-                ),
-                other.span().unwrap_or(head),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/add.rs

@@ -122,13 +122,15 @@ fn add(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => add_impl(val, args, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/at.rs

@@ -30,7 +30,9 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
         Value::List { mut vals, span } => {
             if vals.len() != 2 {
                 return Err(ShellError::UnsupportedInput(
-                    "More than two indices given".to_string(),
+                    "More than two indices in range".to_string(),
+                    "value originates from here".to_string(),
+                    head,
                     span,
                 ));
             } else {
@@ -38,10 +40,14 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
                 let end = match end {
                     Value::Int { val, .. } => val.to_string(),
                     Value::String { val, .. } => val,
+                    // Explicitly propagate errors instead of dropping them.
+                    Value::Error { error } => return Err(error),
                     other => {
                         return Err(ShellError::UnsupportedInput(
-                            "could not perform subbytes. Expecting a string or int".to_string(),
-                            other.span().unwrap_or(head),
+                            "Only string or list<int> ranges are supported".into(),
+                            format!("input type: {:?}", other.get_type()),
+                            head,
+                            other.expect_span(),
                         ))
                     }
                 };
@@ -49,10 +55,14 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
                 let start = match start {
                     Value::Int { val, .. } => val.to_string(),
                     Value::String { val, .. } => val,
+                    // Explicitly propagate errors instead of dropping them.
+                    Value::Error { error } => return Err(error),
                     other => {
                         return Err(ShellError::UnsupportedInput(
-                            "could not perform subbytes. Expecting a string or int".to_string(),
-                            other.span().unwrap_or(head),
+                            "Only string or list<int> ranges are supported".into(),
+                            format!("input type: {:?}", other.get_type()),
+                            head,
+                            other.expect_span(),
                         ))
                     }
                 };
@@ -66,15 +76,21 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
                 None => {
                     return Err(ShellError::UnsupportedInput(
                         "could not perform subbytes".to_string(),
+                        "with this range".to_string(),
+                        head,
                         span,
                     ))
                 }
             }
         }
+        // Explicitly propagate errors instead of dropping them.
+        Value::Error { error } => return Err(error),
         other => {
             return Err(ShellError::UnsupportedInput(
                 "could not perform subbytes".to_string(),
-                other.span().unwrap_or(head),
+                "with this range".to_string(),
+                head,
+                other.expect_span(),
             ))
         }
     };
@@ -87,6 +103,8 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
             Err(_) => {
                 return Err(ShellError::UnsupportedInput(
                     "could not perform subbytes".to_string(),
+                    "with this range".to_string(),
+                    head,
                     span,
                 ))
             }
@@ -100,6 +118,8 @@ fn parse_range(range: Value, head: Span) -> Result<(isize, isize, Span), ShellEr
             Err(_) => {
                 return Err(ShellError::UnsupportedInput(
                     "could not perform subbytes".to_string(),
+                    "with this range".to_string(),
+                    head,
                     span,
                 ))
             }
@@ -232,13 +252,15 @@ fn at(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => at_impl(val, args, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "integer".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }
@@ -262,7 +284,7 @@ fn at_impl(input: &[u8], arg: &Arguments, span: Span) -> Value {
         match start.cmp(&end) {
             Ordering::Equal => Value::Binary { val: vec![], span },
             Ordering::Greater => Value::Error {
-                error: ShellError::UnsupportedInput(
+                error: ShellError::TypeMismatch(
                     "End must be greater than or equal to Start".to_string(),
                     arg.arg_span,
                 ),

crates/nu-command/src/bytes/build_.rs

@@ -52,10 +52,12 @@ impl Command for BytesBuild {
             let val = eval_expression(engine_state, stack, expr)?;
             match val {
                 Value::Binary { mut val, .. } => output.append(&mut val),
+                // Explicitly propagate errors instead of dropping them.
+                Value::Error { error } => return Err(error),
                 other => {
-                    return Err(ShellError::UnsupportedInput(
-                        "only support expression which yields to binary data".to_string(),
-                        other.span().unwrap_or(call.head),
+                    return Err(ShellError::TypeMismatch(
+                        "only binary data arguments are supported".to_string(),
+                        other.expect_span(),
                     ))
                 }
             }

crates/nu-command/src/bytes/bytes_.rs

@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, Signature, Value,
+    Category, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,13 +14,19 @@ impl Command for Bytes {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("bytes").category(Category::Bytes)
+        Signature::build("bytes")
+            .category(Category::Bytes)
+            .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
     fn usage(&self) -> &str {
         "Various commands for working with byte data"
     }
 
+    fn extra_usage(&self) -> &str {
+        "You must use one of the following subcommands. Using this command as-is will only produce this help message."
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,
@@ -41,15 +47,3 @@ impl Command for Bytes {
         .into_pipeline_data())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use crate::Bytes;
-
-    #[test]
-    fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(Bytes {})
-    }
-}

crates/nu-command/src/bytes/collect.rs

@@ -54,14 +54,16 @@ impl Command for BytesCollect {
                         output_binary.append(&mut work_sep)
                     }
                 }
+                // Explicitly propagate errors instead of dropping them.
+                Value::Error { error } => return Err(error),
                 other => {
-                    return Err(ShellError::UnsupportedInput(
-                        format!(
-                            "The element type is {}, this command only works with bytes.",
-                            other.get_type()
-                        ),
-                        other.span().unwrap_or(call.head),
-                    ))
+                    return Err(ShellError::OnlySupportsThisInputType(
+                        "integer".into(),
+                        other.get_type().to_string(),
+                        call.head,
+                        // This line requires the Value::Error match above.
+                        other.expect_span(),
+                    ));
                 }
             }
         }

crates/nu-command/src/bytes/ends_with.rs

@@ -68,17 +68,17 @@ impl Command for BytesEndsWith {
             Example {
                 description: "Checks if binary ends with `0x[AA]`",
                 example: "0x[1F FF AA AA] | bytes ends-with 0x[AA]",
-                result: Some(Value::boolean(true, Span::test_data())),
+                result: Some(Value::test_bool(true)),
             },
             Example {
                 description: "Checks if binary ends with `0x[FF AA AA]`",
                 example: "0x[1F FF AA AA] | bytes ends-with 0x[FF AA AA]",
-                result: Some(Value::boolean(true, Span::test_data())),
+                result: Some(Value::test_bool(true)),
             },
             Example {
                 description: "Checks if binary ends with `0x[11]`",
                 example: "0x[1F FF AA AA] | bytes ends-with 0x[11]",
-                result: Some(Value::boolean(false, Span::test_data())),
+                result: Some(Value::test_bool(false)),
             },
         ]
     }
@@ -90,13 +90,15 @@ fn ends_with(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => Value::boolean(val.ends_with(&args.pattern), *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/index_of.rs

@@ -132,13 +132,15 @@ fn index_of(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => index_of_impl(val, args, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/length.rs

@@ -71,13 +71,15 @@ fn length(val: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
             val,
             span: val_span,
         } => Value::int(val.len() as i64, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/remove.rs

@@ -61,7 +61,7 @@ impl Command for BytesRemove {
         let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
         let pattern_to_remove = call.req::<Spanned<Vec<u8>>>(engine_state, stack, 0)?;
         if pattern_to_remove.item.is_empty() {
-            return Err(ShellError::UnsupportedInput(
+            return Err(ShellError::TypeMismatch(
                 "the pattern to remove cannot be empty".to_string(),
                 pattern_to_remove.span,
             ));
@@ -139,13 +139,15 @@ fn remove(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => remove_impl(val, args, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }
@@ -191,7 +193,7 @@ fn remove_impl(input: &[u8], arg: &Arguments, span: Span) -> Value {
                 right += 1;
             }
         }
-        // append the remaing thing to result, this can happened when
+        // append the remaining thing to result, this can happened when
         // we have something to remove and remove_all is False.
         let mut remain = input[left..].to_vec();
         result.append(&mut remain);

crates/nu-command/src/bytes/replace.rs

@@ -61,7 +61,7 @@ impl Command for BytesReplace {
         let cell_paths = (!cell_paths.is_empty()).then_some(cell_paths);
         let find = call.req::<Spanned<Vec<u8>>>(engine_state, stack, 0)?;
         if find.item.is_empty() {
-            return Err(ShellError::UnsupportedInput(
+            return Err(ShellError::TypeMismatch(
                 "the pattern to find cannot be empty".to_string(),
                 find.span,
             ));
@@ -130,13 +130,15 @@ fn replace(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => replace_impl(val, args, *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/reverse.rs

@@ -81,13 +81,15 @@ fn reverse(val: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
                 span: *val_span,
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/bytes/starts_with.rs

@@ -74,17 +74,17 @@ impl Command for BytesStartsWith {
             Example {
                 description: "Checks if binary starts with `0x[1F FF AA]`",
                 example: "0x[1F FF AA AA] | bytes starts-with 0x[1F FF AA]",
-                result: Some(Value::boolean(true, Span::test_data())),
+                result: Some(Value::test_bool(true)),
             },
             Example {
                 description: "Checks if binary starts with `0x[1F]`",
                 example: "0x[1F FF AA AA] | bytes starts-with 0x[1F]",
-                result: Some(Value::boolean(true, Span::test_data())),
+                result: Some(Value::test_bool(true)),
             },
             Example {
                 description: "Checks if binary starts with `0x[1F]`",
                 example: "0x[1F FF AA AA] | bytes starts-with 0x[11]",
-                result: Some(Value::boolean(false, Span::test_data())),
+                result: Some(Value::test_bool(false)),
             },
         ]
     }
@@ -96,13 +96,15 @@ fn starts_with(val: &Value, args: &Arguments, span: Span) -> Value {
             val,
             span: val_span,
         } => Value::boolean(val.starts_with(&args.pattern), *val_span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => val.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!(
-                    "Input's type is {}. This command only works with bytes.",
-                    other.get_type()
-                ),
+            error: ShellError::OnlySupportsThisInputType(
+                "binary".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/charting/hashable_value.rs

@@ -78,13 +78,14 @@ impl HashableValue {
             Value::String { val, span } => Ok(HashableValue::String { val, span }),
             Value::Binary { val, span } => Ok(HashableValue::Binary { val, span }),
 
-            _ => {
-                let input_span = value.span().unwrap_or(span);
-                Err(ShellError::UnsupportedInput(
-                    format!("input value {value:?} is not hashable"),
-                    input_span,
-                ))
-            }
+            // Explicitly propagate errors instead of dropping them.
+            Value::Error { error } => Err(error),
+            _ => Err(ShellError::UnsupportedInput(
+                "input value is not hashable".into(),
+                format!("input type: {:?}", value.get_type()),
+                span,
+                value.expect_span(),
+            )),
         }
     }
 

crates/nu-command/src/charting/histogram.rs

@@ -98,12 +98,11 @@ impl Command for Histogram {
         let frequency_name_arg = call.opt::<Spanned<String>>(engine_state, stack, 1)?;
         let frequency_column_name = match frequency_name_arg {
             Some(inner) => {
-                let span = inner.span;
                 if ["value", "count", "quantile", "percentage"].contains(&inner.item.as_str()) {
-                    return Err(ShellError::UnsupportedInput(
+                    return Err(ShellError::TypeMismatch(
                         "frequency-column-name can't be 'value', 'count' or 'percentage'"
                             .to_string(),
-                        span,
+                        inner.span,
                     ));
                 }
                 inner.item
@@ -119,7 +118,7 @@ impl Command for Histogram {
                 "normalize" => PercentageCalcMethod::Normalize,
                 "relative" => PercentageCalcMethod::Relative,
                 _ => {
-                    return Err(ShellError::UnsupportedInput(
+                    return Err(ShellError::TypeMismatch(
                         "calc method can only be 'normalize' or 'relative'".to_string(),
                         inner.span,
                     ))
@@ -137,6 +136,8 @@ impl Command for Histogram {
                 frequency_column_name,
                 calc_method,
                 span,
+                // Note that as_list() filters out Value::Error here.
+                data_as_value.expect_span(),
             ),
             Err(e) => Err(e),
         }
@@ -149,6 +150,7 @@ fn run_histogram(
     freq_column: String,
     calc_method: PercentageCalcMethod,
     head_span: Span,
+    list_span: Span,
 ) -> Result<PipelineData, ShellError> {
     let mut inputs = vec![];
     // convert from inputs to hashable values.
@@ -157,14 +159,24 @@ fn run_histogram(
             // some invalid input scenario needs to handle:
             // Expect input is a list of hashable value, if one value is not hashable, throw out error.
             for v in values {
-                let current_span = v.span().unwrap_or(head_span);
-                inputs.push(HashableValue::from_value(v, head_span).map_err(|_| {
-                    ShellError::UnsupportedInput(
-                        "--column-name is not provided, can only support a list of simple value."
-                            .to_string(),
-                        current_span,
-                    )
-                })?);
+                match v {
+                    // Propagate existing errors.
+                    Value::Error { error } => return Err(error),
+                    _ => {
+                        let t = v.get_type();
+                        let span = v.expect_span();
+                        inputs.push(HashableValue::from_value(v, head_span).map_err(|_| {
+                        ShellError::UnsupportedInput(
+                            "Since --column-name was not provided, only lists of hashable values are supported.".to_string(),
+                            format!(
+                                "input type: {:?}", t
+                            ),
+                            head_span,
+                            span,
+                        )
+                    })?)
+                    }
+                }
             }
         }
         Some(ref col) => {
@@ -186,14 +198,17 @@ fn run_histogram(
                             }
                         }
                     }
+                    // Propagate existing errors.
+                    Value::Error { error } => return Err(error),
                     _ => continue,
                 }
             }
 
             if inputs.is_empty() {
-                return Err(ShellError::UnsupportedInput(
-                    format!("expect input is table, and inputs doesn't contain any value which has {col_name} column"),
+                return Err(ShellError::CantFindColumn(
+                    col_name.clone(),
                     head_span,
+                    list_span,
                 ));
             }
         }

crates/nu-command/src/conversions/fmt.rs

@@ -44,14 +44,14 @@ impl Command for Fmt {
                     "upperhex".into(),
                 ],
                 vals: vec![
-                    Value::string("0b101010", Span::test_data()),
-                    Value::string("42", Span::test_data()),
-                    Value::string("42", Span::test_data()),
-                    Value::string("4.2e1", Span::test_data()),
-                    Value::string("0x2a", Span::test_data()),
-                    Value::string("0o52", Span::test_data()),
-                    Value::string("4.2E1", Span::test_data()),
-                    Value::string("0x2A", Span::test_data()),
+                    Value::test_string("0b101010"),
+                    Value::test_string("42"),
+                    Value::test_string("42"),
+                    Value::test_string("4.2e1"),
+                    Value::test_string("0x2a"),
+                    Value::test_string("0o52"),
+                    Value::test_string("4.2E1"),
+                    Value::test_string("0x2A"),
                 ],
                 span: Span::test_data(),
             }),
@@ -84,10 +84,15 @@ fn action(input: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
     match input {
         Value::Int { val, .. } => fmt_it(*val, span),
         Value::Filesize { val, .. } => fmt_it(*val, span),
-        _ => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!("unsupported input type: {:?}", input.get_type()),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "integer or filesize".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/conversions/into/binary.rs

@@ -177,13 +177,24 @@ pub fn action(input: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
             val: int_to_endian(i64::from(*val)),
             span,
         },
+        Value::Duration { val, .. } => Value::Binary {
+            val: int_to_endian(*val),
+            span,
+        },
         Value::Date { val, .. } => Value::Binary {
             val: val.format("%c").to_string().as_bytes().to_vec(),
             span,
         },
-
-        _ => Value::Error {
-            error: ShellError::UnsupportedInput("'into binary' for unsupported type".into(), span),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "integer, float, filesize, string, date, duration, binary or bool".into(),
+                other.get_type().to_string(),
+                span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
+            ),
         },
     }
 }

crates/nu-command/src/conversions/into/bool.rs

@@ -163,10 +163,15 @@ fn action(input: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
             Ok(val) => Value::Bool { val, span },
             Err(error) => Value::Error { error },
         },
-        _ => Value::Error {
-            error: ShellError::UnsupportedInput(
-                "'into bool' does not support this input".into(),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "bool, integer, float or string".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/conversions/into/command.rs

@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, Signature, Value,
+    Category, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,13 +14,19 @@ impl Command for Into {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("into").category(Category::Conversions)
+        Signature::build("into")
+            .category(Category::Conversions)
+            .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
     fn usage(&self) -> &str {
         "Commands to convert data from one type to another."
     }
 
+    fn extra_usage(&self) -> &str {
+        "You must use one of the following subcommands. Using this command as-is will only produce this help message."
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,
@@ -41,15 +47,3 @@ impl Command for Into {
         .into_pipeline_data())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(Into {})
-    }
-}

crates/nu-command/src/conversions/into/datetime.rs

@@ -147,41 +147,19 @@ impl Command for SubCommand {
     }
 
     fn examples(&self) -> Vec<Example> {
-        let example_result_1 = |secs: i64, nsecs: u32| {
-            let dt = match Utc.timestamp_opt(secs, nsecs) {
-                LocalResult::Single(dt) => Some(dt),
-                _ => None,
-            };
-            match dt {
-                Some(dt) => Some(Value::Date {
-                    val: dt.into(),
-                    span: Span::test_data(),
-                }),
-                None => Some(Value::Error {
-                    error: ShellError::UnsupportedInput(
-                        "The given datetime representation is unsupported.".to_string(),
-                        Span::test_data(),
-                    ),
-                }),
-            }
+        let example_result_1 = |secs: i64, nsecs: u32| match Utc.timestamp_opt(secs, nsecs) {
+            LocalResult::Single(dt) => Some(Value::Date {
+                val: dt.into(),
+                span: Span::test_data(),
+            }),
+            _ => panic!("datetime: help example is invalid"),
         };
-        let example_result_2 = |millis: i64| {
-            let dt = match Utc.timestamp_millis_opt(millis) {
-                LocalResult::Single(dt) => Some(dt),
-                _ => None,
-            };
-            match dt {
-                Some(dt) => Some(Value::Date {
-                    val: dt.into(),
-                    span: Span::test_data(),
-                }),
-                None => Some(Value::Error {
-                    error: ShellError::UnsupportedInput(
-                        "The given datetime representation is unsupported.".to_string(),
-                        Span::test_data(),
-                    ),
-                }),
-            }
+        let example_result_2 = |millis: i64| match Utc.timestamp_millis_opt(millis) {
+            LocalResult::Single(dt) => Some(Value::Date {
+                val: dt.into(),
+                span: Span::test_data(),
+            }),
+            _ => panic!("datetime: help example is invalid"),
         };
         vec![
             Example {
@@ -213,7 +191,7 @@ impl Command for SubCommand {
             },
             Example {
                 description:
-                    "Convert timestamps like the sqlite history t",
+                    "Convert a millisecond-precise timestamp",
                 example: "1656165681720 | into datetime",
                 result: example_result_2(1656165681720)
             },
@@ -231,11 +209,16 @@ fn action(input: &Value, args: &Arguments, head: Span) -> Value {
     let timestamp = match input {
         Value::Int { val, .. } => Ok(*val),
         Value::String { val, .. } => val.parse::<i64>(),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => return input.clone(),
         other => {
             return Value::Error {
-                error: ShellError::UnsupportedInput(
-                    format!("Expected string or int, got {} instead", other.get_type()),
+                error: ShellError::OnlySupportsThisInputType(
+                    "string and integer".into(),
+                    other.get_type().to_string(),
                     head,
+                    // This line requires the Value::Error match above.
+                    other.expect_span(),
                 ),
             };
         }
@@ -248,113 +231,68 @@ fn action(input: &Value, args: &Arguments, head: Span) -> Value {
         if ts.abs() > TIMESTAMP_BOUND {
             return Value::Error {
                 error: ShellError::UnsupportedInput(
-                    "Given timestamp is out of range, it should between -8e+12 and 8e+12"
-                        .to_string(),
+                    "timestamp is out of range; it should between -8e+12 and 8e+12".to_string(),
+                    format!("timestamp is {:?}", ts),
                     head,
+                    // Again, can safely unwrap this from here on
+                    input.expect_span(),
                 ),
             };
         }
 
+        macro_rules! match_datetime {
+            ($expr:expr) => {
+                match $expr {
+                    LocalResult::Single(dt) => Value::Date {
+                        val: dt.into(),
+                        span: head,
+                    },
+                    _ => {
+                        return Value::Error {
+                            error: ShellError::UnsupportedInput(
+                                "The given local datetime representation is invalid.".into(),
+                                format!("timestamp is {:?}", ts),
+                                head,
+                                head,
+                            ),
+                        };
+                    }
+                }
+            };
+        }
+
         return match timezone {
             // default to UTC
             None => {
                 // be able to convert chrono::Utc::now()
-                let dt = match ts.to_string().len() {
-                    x if x > 13 => Utc.timestamp_nanos(ts).into(),
-                    x if x > 10 => match Utc.timestamp_millis_opt(ts) {
-                        LocalResult::Single(dt) => dt.into(),
-                        _ => {
-                            return Value::Error {
-                                // This error message is from chrono
-                                error: ShellError::UnsupportedInput(
-                                    "The given local datetime representation is invalid."
-                                        .to_string(),
-                                    head,
-                                ),
-                            };
-                        }
+                match ts.to_string().len() {
+                    x if x > 13 => Value::Date {
+                        val: Utc.timestamp_nanos(ts).into(),
+                        span: head,
                     },
-                    _ => match Utc.timestamp_opt(ts, 0) {
-                        LocalResult::Single(dt) => dt.into(),
-                        _ => {
-                            return Value::Error {
-                                error: ShellError::UnsupportedInput(
-                                    "The given local datetime representation is invalid."
-                                        .to_string(),
-                                    head,
-                                ),
-                            }
-                        }
-                    },
-                };
-
-                Value::Date {
-                    val: dt,
-                    span: head,
+                    x if x > 10 => match_datetime!(Utc.timestamp_millis_opt(ts)),
+                    _ => match_datetime!(Utc.timestamp_opt(ts, 0)),
                 }
             }
             Some(Spanned { item, span }) => match item {
-                Zone::Utc => match Utc.timestamp_opt(ts, 0) {
-                    LocalResult::Single(val) => Value::Date {
-                        val: val.into(),
-                        span: head,
-                    },
-                    _ => Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            "The given local datetime representation is invalid.".to_string(),
-                            *span,
-                        ),
-                    },
-                },
-                Zone::Local => match Local.timestamp_opt(ts, 0) {
-                    LocalResult::Single(val) => Value::Date {
-                        val: val.into(),
-                        span: head,
-                    },
-                    _ => Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            "The given local datetime representation is invalid.".to_string(),
-                            *span,
-                        ),
-                    },
-                },
+                Zone::Utc => match_datetime!(Utc.timestamp_opt(ts, 0)),
+                Zone::Local => match_datetime!(Local.timestamp_opt(ts, 0)),
                 Zone::East(i) => match FixedOffset::east_opt((*i as i32) * HOUR) {
-                    Some(eastoffset) => match eastoffset.timestamp_opt(ts, 0) {
-                        LocalResult::Single(val) => Value::Date { val, span: head },
-                        _ => Value::Error {
-                            error: ShellError::UnsupportedInput(
-                                "The given local datetime representation is invalid.".to_string(),
-                                *span,
-                            ),
-                        },
-                    },
+                    Some(eastoffset) => match_datetime!(eastoffset.timestamp_opt(ts, 0)),
                     None => Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            "The given local datetime representation is invalid.".to_string(),
-                            *span,
-                        ),
+                        error: ShellError::DatetimeParseError(*span),
                     },
                 },
                 Zone::West(i) => match FixedOffset::west_opt((*i as i32) * HOUR) {
-                    Some(westoffset) => match westoffset.timestamp_opt(ts, 0) {
-                        LocalResult::Single(val) => Value::Date { val, span: head },
-                        _ => Value::Error {
-                            error: ShellError::UnsupportedInput(
-                                "The given local datetime representation is invalid.".to_string(),
-                                *span,
-                            ),
-                        },
-                    },
+                    Some(westoffset) => match_datetime!(westoffset.timestamp_opt(ts, 0)),
                     None => Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            "The given local datetime representation is invalid.".to_string(),
-                            *span,
-                        ),
+                        error: ShellError::DatetimeParseError(*span),
                     },
                 },
                 Zone::Error => Value::Error {
-                    error: ShellError::UnsupportedInput(
-                        "Cannot convert given timezone or offset to timestamp".to_string(),
+                    // This is an argument error, not an input error
+                    error: ShellError::TypeMismatch(
+                        "Invalid timezone or offset".to_string(),
                         *span,
                     ),
                 },
@@ -391,10 +329,15 @@ fn action(input: &Value, args: &Arguments, head: Span) -> Value {
                 },
             }
         }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
         other => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!("Expected string, got {} instead", other.get_type()),
+            error: ShellError::OnlySupportsThisInputType(
+                "string".into(),
+                other.get_type().to_string(),
                 head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/conversions/into/decimal.rs

@@ -105,18 +105,17 @@ fn action(input: &Value, _args: &CellPathOnlyArgs, head: Span) -> Value {
             },
             span: *span,
         },
-        other => {
-            let span = other.span();
-            match span {
-                Ok(s) => {
-                    let got = format!("Expected a string, got {} instead", other.get_type());
-                    Value::Error {
-                        error: ShellError::UnsupportedInput(got, s),
-                    }
-                }
-                Err(e) => Value::Error { error: e },
-            }
-        }
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "string, integer or bool".into(),
+                other.get_type().to_string(),
+                head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
+            ),
+        },
     }
 }
 

crates/nu-command/src/conversions/into/duration.rs

@@ -468,9 +468,11 @@ fn action(
                     }
                 } else {
                     Value::Error {
-                        error: ShellError::UnsupportedInput(
-                            "'into duration' does not support this string input".into(),
+                        error: ShellError::CantConvert(
+                            "string".into(),
+                            "duration".into(),
                             span,
+                            None,
                         ),
                     }
                 }
@@ -481,10 +483,15 @@ fn action(
                 }
             }
         }
-        _ => Value::Error {
-            error: ShellError::UnsupportedInput(
-                "'into duration' does not support this input".into(),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "string or duration".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }

crates/nu-command/src/conversions/into/filesize.rs

@@ -116,20 +116,18 @@ pub fn action(input: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
                 val: 0,
                 span: value_span,
             },
-            _ => Value::Error {
-                error: ShellError::UnsupportedInput(
-                    "'into filesize' for unsupported type".into(),
+            other => Value::Error {
+                error: ShellError::OnlySupportsThisInputType(
+                    "string and integer".into(),
+                    other.get_type().to_string(),
+                    span,
                     value_span,
                 ),
             },
         }
     } else {
-        Value::Error {
-            error: ShellError::UnsupportedInput(
-                "'into filesize' for unsupported type".into(),
-                span,
-            ),
-        }
+        // Propagate existing errors
+        input.clone()
     }
 }
 fn int_from_string(a_string: &str, span: Span) -> Result<i64, ShellError> {

crates/nu-command/src/conversions/into/int.rs

@@ -70,7 +70,7 @@ impl Command for SubCommand {
         let radix: u32 = match radix {
             Some(Value::Int { val, span }) => {
                 if !(2..=36).contains(&val) {
-                    return Err(ShellError::UnsupportedInput(
+                    return Err(ShellError::TypeMismatch(
                         "Radix must lie in the range [2, 36]".to_string(),
                         span,
                     ));
@@ -113,7 +113,7 @@ impl Command for SubCommand {
             Example {
                 description: "Convert file size to integer",
                 example: "4KB | into int",
-                result: Some(Value::int(4000, Span::test_data())),
+                result: Some(Value::test_int(4000)),
             },
             Example {
                 description: "Convert bool to integer",
@@ -187,9 +187,11 @@ fn action(input: &Value, args: &Arguments, span: Span) -> Value {
                         Ok(v) => v,
                         _ => {
                             return Value::Error {
-                                error: ShellError::UnsupportedInput(
-                                    "Could not convert float to integer".to_string(),
+                                error: ShellError::CantConvert(
+                                    "float".to_string(),
+                                    "integer".to_string(),
                                     span,
+                                    None,
                                 ),
                             }
                         }
@@ -219,6 +221,7 @@ fn action(input: &Value, args: &Arguments, span: Span) -> Value {
             val: val.timestamp(),
             span,
         },
+        Value::Duration { val, .. } => Value::Int { val: *val, span },
         Value::Binary { val, span } => {
             use byteorder::{BigEndian, ByteOrder, LittleEndian};
 
@@ -240,10 +243,15 @@ fn action(input: &Value, args: &Arguments, span: Span) -> Value {
                 Value::int(BigEndian::read_i64(&val), *span)
             }
         }
-        _ => Value::Error {
-            error: ShellError::UnsupportedInput(
-                format!("'into int' for unsupported type '{}'", input.get_type()),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => input.clone(),
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "integer, float, filesize, date, string, binary, duration or bool".into(),
+                other.get_type().to_string(),
                 span,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
             ),
         },
     }
@@ -281,13 +289,18 @@ fn convert_int(input: &Value, head: Span, radix: u32) -> Value {
             }
             val.to_string()
         }
-        _ => {
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { .. } => return input.clone(),
+        other => {
             return Value::Error {
-                error: ShellError::UnsupportedInput(
-                    "only strings or integers are supported".to_string(),
+                error: ShellError::OnlySupportsThisInputType(
+                    "string and integer".into(),
+                    other.get_type().to_string(),
                     head,
+                    // This line requires the Value::Error match above.
+                    other.expect_span(),
                 ),
-            }
+            };
         }
     };
     match i64::from_str_radix(i.trim(), radix) {

crates/nu-command/src/conversions/into/record.rs

@@ -183,12 +183,16 @@ fn into_record(
             Value::Record { cols, vals, span }
         }
         Value::Record { cols, vals, span } => Value::Record { cols, vals, span },
-        other => {
-            return Err(ShellError::UnsupportedInput(
-                "'into record' does not support this input".into(),
-                other.span().unwrap_or(call.head),
-            ))
-        }
+        Value::Error { .. } => input,
+        other => Value::Error {
+            error: ShellError::OnlySupportsThisInputType(
+                "string".into(),
+                other.get_type().to_string(),
+                call.head,
+                // This line requires the Value::Error match above.
+                other.expect_span(),
+            ),
+        },
     };
     Ok(res.into_pipeline_data())
 }

crates/nu-command/src/conversions/into/string.rs

@@ -79,22 +79,22 @@ impl Command for SubCommand {
             Example {
                 description: "convert integer to string and append three decimal places",
                 example: "5 | into string -d 3",
-                result: Some(Value::string("5.000", Span::test_data())),
+                result: Some(Value::test_string("5.000")),
             },
             Example {
                 description: "convert decimal to string and round to nearest integer",
                 example: "1.7 | into string -d 0",
-                result: Some(Value::string("2", Span::test_data())),
+                result: Some(Value::test_string("2")),
             },
             Example {
                 description: "convert decimal to string",
                 example: "1.7 | into string -d 1",
-                result: Some(Value::string("1.7", Span::test_data())),
+                result: Some(Value::test_string("1.7")),
             },
             Example {
                 description: "convert decimal to string and limit to 2 decimals",
                 example: "1.734 | into string -d 2",
-                result: Some(Value::string("1.73", Span::test_data())),
+                result: Some(Value::test_string("1.73")),
             },
             Example {
                 description: "try to convert decimal to string and provide negative decimal points",
@@ -111,17 +111,17 @@ impl Command for SubCommand {
             Example {
                 description: "convert decimal to string",
                 example: "4.3 | into string",
-                result: Some(Value::string("4.3", Span::test_data())),
+                result: Some(Value::test_string("4.3")),
             },
             Example {
                 description: "convert string to string",
                 example: "'1234' | into string",
-                result: Some(Value::string("1234", Span::test_data())),
+                result: Some(Value::test_string("1234")),
             },
             Example {
                 description: "convert boolean to string",
                 example: "true | into string",
-                result: Some(Value::string("true", Span::test_data())),
+                result: Some(Value::test_string("true")),
             },
             // TODO: This should work but does not; see https://github.com/nushell/nushell/issues/7032
             // Example {
@@ -154,7 +154,7 @@ fn string_helper(
     let decimals_value: Option<i64> = call.get_flag(engine_state, stack, "decimals")?;
     if let Some(decimal_val) = decimals_value {
         if decimals && decimal_val.is_negative() {
-            return Err(ShellError::UnsupportedInput(
+            return Err(ShellError::TypeMismatch(
                 "Cannot accept negative integers for decimals arguments".to_string(),
                 head,
             ));
@@ -251,9 +251,11 @@ fn action(input: &Value, args: &Arguments, span: Span) -> Value {
             vals: _,
             span: _,
         } => Value::Error {
-            error: ShellError::UnsupportedInput(
-                "Cannot convert Record into string".to_string(),
+            error: ShellError::CantConvert(
+                "record".into(),
+                "string".into(),
                 span,
+                Some("try using the `to nuon` command".into()),
             ),
         },
         Value::Binary { .. } => Value::Error {

crates/nu-command/src/core_commands/const_.rs

@@ -0,0 +1,104 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type};
+
+#[derive(Clone)]
+pub struct Const;
+
+impl Command for Const {
+    fn name(&self) -> &str {
+        "const"
+    }
+
+    fn usage(&self) -> &str {
+        "Create a parse-time constant."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("const")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
+            .required("const_name", SyntaxShape::VarWithOptType, "constant name")
+            .required(
+                "initial_value",
+                SyntaxShape::Keyword(b"=".to_vec(), Box::new(SyntaxShape::Expression)),
+                "equals sign followed by constant value",
+            )
+            .category(Category::Core)
+    }
+
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check:
+  https://www.nushell.sh/book/thinking_in_nu.html"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["set", "let"]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+        let var_id = call
+            .positional_nth(0)
+            .expect("checked through parser")
+            .as_var()
+            .expect("internal error: missing variable");
+
+        if let Some(constval) = engine_state.find_constant(var_id, &[]) {
+            // Instead of creating a second copy of the value in the stack, we could change
+            // stack.get_var() to check engine_state.find_constant().
+            stack.add_var(var_id, constval.clone());
+
+            Ok(PipelineData::empty())
+        } else {
+            Err(ShellError::NushellFailedSpanned(
+                "Missing Constant".to_string(),
+                "constant not added by the parser".to_string(),
+                call.head,
+            ))
+        }
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Create a new parse-time constant.",
+                example: "const x = 10",
+                result: None,
+            },
+            Example {
+                description: "Create a composite constant value",
+                example: "const x = { a: 10, b: 20 }",
+                result: None,
+            },
+        ]
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use nu_protocol::engine::CommandType;
+
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(Const {})
+    }
+
+    #[test]
+    fn test_command_type() {
+        assert!(matches!(Const.command_type(), CommandType::Keyword));
+    }
+}

crates/nu-command/src/core_commands/debug.rs

@@ -39,6 +39,8 @@ impl Command for Debug {
         let config = engine_state.get_config().clone();
         let raw = call.has_flag("raw");
 
+        // Should PipelineData::Empty result in an error here?
+
         input.map(
             move |x| {
                 if raw {

crates/nu-command/src/core_commands/def_env.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct DefEnv;
@@ -72,7 +72,7 @@ def-env cd_with_fallback [arg = ""] {
         vec![Example {
             description: "Set environment variable by call a custom command",
             example: r#"def-env foo [] { let-env BAR = "BAZ" }; foo; $env.BAR"#,
-            result: Some(Value::string("BAZ", Span::test_data())),
+            result: Some(Value::test_string("BAZ")),
         }]
     }
 }

crates/nu-command/src/core_commands/describe.rs

@@ -19,6 +19,11 @@ impl Command for Describe {
     fn signature(&self) -> Signature {
         Signature::build("describe")
             .input_output_types(vec![(Type::Any, Type::String)])
+            .switch(
+                "no-collect",
+                "do not collect streams of structured data",
+                Some('n'),
+            )
             .category(Category::Core)
     }
 
@@ -30,32 +35,58 @@ impl Command for Describe {
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
         let head = call.head;
-        if matches!(input, PipelineData::ExternalStream { .. }) {
-            Ok(PipelineData::Value(
-                Value::string("raw input", call.head),
-                None,
-            ))
-        } else {
-            let value = input.into_value(call.head);
-            let description = match value {
-                Value::CustomValue { val, .. } => val.value_string(),
-                _ => value.get_type().to_string(),
-            };
 
-            Ok(Value::String {
-                val: description,
-                span: head,
+        let no_collect: bool = call.has_flag("no-collect");
+
+        let description = match input {
+            PipelineData::ExternalStream { .. } => "raw input".into(),
+            PipelineData::ListStream(_, _) => {
+                if no_collect {
+                    "stream".into()
+                } else {
+                    let value = input.into_value(head);
+                    let base_description = match value {
+                        Value::CustomValue { val, .. } => val.value_string(),
+                        _ => value.get_type().to_string(),
+                    };
+
+                    format!("{base_description} (stream)")
+                }
             }
-            .into_pipeline_data())
+            _ => {
+                let value = input.into_value(head);
+                match value {
+                    Value::CustomValue { val, .. } => val.value_string(),
+                    _ => value.get_type().to_string(),
+                }
+            }
+        };
+
+        Ok(Value::String {
+            val: description,
+            span: head,
         }
+        .into_pipeline_data())
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Describe the type of a string",
-            example: "'hello' | describe",
-            result: Some(Value::test_string("string")),
-        }]
+        vec![
+            Example {
+                description: "Describe the type of a string",
+                example: "'hello' | describe",
+                result: Some(Value::test_string("string")),
+            },
+            Example {
+                description: "Describe a stream of data, collecting it first",
+                example: "[1 2 3] | each {|i| $i} | describe",
+                result: Some(Value::test_string("list<int> (stream)")),
+            },
+            Example {
+                description: "Describe the input but do not collect streams",
+                example: "[1 2 3] | each {|i| $i} | describe --no-collect",
+                result: Some(Value::test_string("stream")),
+            },
+        ]
     }
 
     fn search_terms(&self) -> Vec<&str> {

crates/nu-command/src/core_commands/error_make.rs

@@ -2,7 +2,7 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -15,6 +15,7 @@ impl Command for ErrorMake {
 
     fn signature(&self) -> Signature {
         Signature::build("error make")
+            .input_output_types(vec![(Type::Nothing, Type::Error)])
             .required("error_struct", SyntaxShape::Record, "the error to create")
             .switch(
                 "unspanned",

crates/nu-command/src/core_commands/export.rs

@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, Example, IntoPipelineData, PipelineData, Signature, Span, Type, Value,
+    Category, Example, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -56,7 +56,7 @@ impl Command for ExportCommand {
         vec![Example {
             description: "Export a definition from a module",
             example: r#"module utils { export def my-command [] { "hello" } }; use utils my-command; my-command"#,
-            result: Some(Value::string("hello", Span::test_data())),
+            result: Some(Value::test_string("hello")),
         }]
     }
 

crates/nu-command/src/core_commands/export_def.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportDef;
@@ -46,7 +46,7 @@ impl Command for ExportDef {
         vec![Example {
             description: "Define a custom command in a module and call it",
             example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
-            result: Some(Value::string("foo", Span::test_data())),
+            result: Some(Value::test_string("foo")),
         }]
     }
 

crates/nu-command/src/core_commands/export_def_env.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportDefEnv;
@@ -72,7 +72,7 @@ export def-env cd_with_fallback [arg = ""] {
         vec![Example {
             description: "Define a custom command that participates in the environment in a module and call it",
             example: r#"module foo { export def-env bar [] { let-env FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
-            result: Some(Value::string("BAZ", Span::test_data())),
+            result: Some(Value::test_string("BAZ")),
         }]
     }
 

crates/nu-command/src/core_commands/export_use.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct ExportUse;
@@ -17,7 +17,12 @@ impl Command for ExportUse {
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("export use")
             .input_output_types(vec![(Type::Nothing, Type::Nothing)])
-            .required("pattern", SyntaxShape::ImportPattern, "import pattern")
+            .required("module", SyntaxShape::String, "Module or module file")
+            .optional(
+                "members",
+                SyntaxShape::Any,
+                "Which members of the module to import",
+            )
             .category(Category::Core)
     }
 
@@ -48,7 +53,7 @@ impl Command for ExportUse {
     use eggs foo
     foo
             "#,
-            result: Some(Value::string("foo", Span::test_data())),
+            result: Some(Value::test_string("foo")),
         }]
     }
 

crates/nu-command/src/core_commands/for_.rs

@@ -2,7 +2,7 @@ use nu_engine::{eval_block, eval_expression, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Block, Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, ListStream, PipelineData, ShellError, Signature, SyntaxShape, Value,
+    Category, Example, ListStream, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,8 @@ impl Command for For {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("for")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required(
                 "var_name",
                 SyntaxShape::VarWithOptType,

crates/nu-command/src/core_commands/help.rs

@@ -1,17 +1,18 @@
+use crate::help_aliases::help_aliases;
+use crate::help_commands::help_commands;
+use crate::help_modules::help_modules;
 use fancy_regex::Regex;
 use nu_ansi_term::{
     Color::{Red, White},
     Style,
 };
-use nu_color_config::StyleComputer;
-use nu_engine::{get_full_help, CallExt};
+use nu_engine::CallExt;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    span, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
-    ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
+    span, Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
+    SyntaxShape, Type, Value,
 };
-use std::borrow::Borrow;
 #[derive(Clone)]
 pub struct Help;
 
@@ -26,7 +27,7 @@ impl Command for Help {
             .rest(
                 "rest",
                 SyntaxShape::String,
-                "the name of command to get help on",
+                "the name of command, alias or module to get help on",
             )
             .named(
                 "find",
@@ -38,7 +39,11 @@ impl Command for Help {
     }
 
     fn usage(&self) -> &str {
-        "Display help information about commands."
+        "Display help information about different parts of Nushell."
+    }
+
+    fn extra_usage(&self) -> &str {
+        r#"`help word` searches for "word" in commands, aliases and modules, in that order."#
     }
 
     fn run(
@@ -48,269 +53,18 @@ impl Command for Help {
         call: &Call,
         _input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        help(engine_state, stack, call)
-    }
+        let head = call.head;
+        let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
+        let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
 
-    fn examples(&self) -> Vec<Example> {
-        vec![
-            Example {
-                description: "show all commands and sub-commands",
-                example: "help commands",
-                result: None,
-            },
-            Example {
-                description: "show help for single command",
-                example: "help match",
-                result: None,
-            },
-            Example {
-                description: "show help for single sub-command",
-                example: "help str lpad",
-                result: None,
-            },
-            Example {
-                description: "search for string in command names, usage and search terms",
-                example: "help --find char",
-                result: None,
-            },
-        ]
-    }
-}
-
-fn help(
-    engine_state: &EngineState,
-    stack: &mut Stack,
-    call: &Call,
-) -> Result<PipelineData, ShellError> {
-    let head = call.head;
-    let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
-    let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
-    let commands = engine_state.get_decl_ids_sorted(false);
-
-    // 🚩The following two-lines are copied from filters/find.rs:
-    let style_computer = StyleComputer::from_config(engine_state, stack);
-    // Currently, search results all use the same style.
-    // Also note that this sample string is passed into user-written code (the closure that may or may not be
-    // defined for "string").
-    let string_style = style_computer.compute("string", &Value::string("search result", head));
-
-    if let Some(f) = find {
-        let org_search_string = f.item.clone();
-        let search_string = f.item.to_lowercase();
-        let mut found_cmds_vec = Vec::new();
-
-        for decl_id in commands {
-            let mut cols = vec![];
-            let mut vals = vec![];
-            let decl = engine_state.get_decl(decl_id);
-            let sig = decl.signature().update_from_command(decl.borrow());
-            let signatures = sig.to_string();
-            let key = sig.name;
-            let usage = sig.usage;
-            let search_terms = sig.search_terms;
-
-            let matches_term = if !search_terms.is_empty() {
-                search_terms
-                    .iter()
-                    .any(|term| term.to_lowercase().contains(&search_string))
-            } else {
-                false
-            };
-
-            let key_match = key.to_lowercase().contains(&search_string);
-            let usage_match = usage.to_lowercase().contains(&search_string);
-            if key_match || usage_match || matches_term {
-                cols.push("name".into());
-                vals.push(Value::String {
-                    val: if key_match {
-                        highlight_search_string(&key, &org_search_string, &string_style)?
-                    } else {
-                        key
-                    },
-                    span: head,
-                });
-
-                cols.push("category".into());
-                vals.push(Value::string(sig.category.to_string(), head));
-
-                cols.push("command_type".into());
-                vals.push(Value::String {
-                    val: format!("{:?}", decl.command_type()).to_lowercase(),
-                    span: head,
-                });
-
-                cols.push("usage".into());
-                vals.push(Value::String {
-                    val: if usage_match {
-                        highlight_search_string(&usage, &org_search_string, &string_style)?
-                    } else {
-                        usage
-                    },
-                    span: head,
-                });
-
-                cols.push("signatures".into());
-                vals.push(Value::String {
-                    val: if decl.is_parser_keyword() {
-                        "".to_string()
-                    } else {
-                        signatures
-                    },
-                    span: head,
-                });
-
-                cols.push("search_terms".into());
-                vals.push(if search_terms.is_empty() {
-                    Value::nothing(head)
-                } else {
-                    Value::String {
-                        val: if matches_term {
-                            search_terms
-                                .iter()
-                                .map(|term| {
-                                    if term.to_lowercase().contains(&search_string) {
-                                        match highlight_search_string(
-                                            term,
-                                            &org_search_string,
-                                            &string_style,
-                                        ) {
-                                            Ok(s) => s,
-                                            Err(_) => {
-                                                string_style.paint(term.to_string()).to_string()
-                                            }
-                                        }
-                                    } else {
-                                        string_style.paint(term.to_string()).to_string()
-                                    }
-                                })
-                                .collect::<Vec<_>>()
-                                .join(", ")
-                        } else {
-                            search_terms.join(", ")
-                        },
-                        span: head,
-                    }
-                });
-
-                found_cmds_vec.push(Value::Record {
-                    cols,
-                    vals,
-                    span: head,
-                });
-            }
-        }
-
-        return Ok(found_cmds_vec
-            .into_iter()
-            .into_pipeline_data(engine_state.ctrlc.clone()));
-    }
-
-    if !rest.is_empty() {
-        let mut found_cmds_vec = Vec::new();
-
-        if rest[0].item == "commands" {
-            for decl_id in commands {
-                let mut cols = vec![];
-                let mut vals = vec![];
-
-                let decl = engine_state.get_decl(decl_id);
-                let sig = decl.signature().update_from_command(decl.borrow());
-
-                let signatures = sig.to_string();
-                let key = sig.name;
-                let usage = sig.usage;
-                let search_terms = sig.search_terms;
-
-                cols.push("name".into());
-                vals.push(Value::String {
-                    val: key,
-                    span: head,
-                });
-
-                cols.push("category".into());
-                vals.push(Value::string(sig.category.to_string(), head));
-
-                cols.push("command_type".into());
-                vals.push(Value::String {
-                    val: format!("{:?}", decl.command_type()).to_lowercase(),
-                    span: head,
-                });
-
-                cols.push("usage".into());
-                vals.push(Value::String {
-                    val: usage,
-                    span: head,
-                });
-
-                cols.push("signatures".into());
-                vals.push(Value::String {
-                    val: if decl.is_parser_keyword() {
-                        "".to_string()
-                    } else {
-                        signatures
-                    },
-                    span: head,
-                });
-
-                cols.push("search_terms".into());
-                vals.push(if search_terms.is_empty() {
-                    Value::nothing(head)
-                } else {
-                    Value::String {
-                        val: search_terms.join(", "),
-                        span: head,
-                    }
-                });
-
-                found_cmds_vec.push(Value::Record {
-                    cols,
-                    vals,
-                    span: head,
-                });
-            }
-
-            Ok(found_cmds_vec
-                .into_iter()
-                .into_pipeline_data(engine_state.ctrlc.clone()))
-        } else {
-            let mut name = String::new();
-
-            for r in &rest {
-                if !name.is_empty() {
-                    name.push(' ');
-                }
-                name.push_str(&r.item);
-            }
-
-            let output = engine_state
-                .get_signatures_with_examples(false)
-                .iter()
-                .filter(|(signature, _, _, _, _)| signature.name == name)
-                .map(|(signature, examples, _, _, is_parser_keyword)| {
-                    get_full_help(signature, examples, engine_state, stack, *is_parser_keyword)
-                })
-                .collect::<Vec<String>>();
-
-            if !output.is_empty() {
-                Ok(Value::String {
-                    val: output.join("======================\n\n"),
-                    span: call.head,
-                }
-                .into_pipeline_data())
-            } else {
-                Err(ShellError::CommandNotFound(span(&[
-                    rest[0].span,
-                    rest[rest.len() - 1].span,
-                ])))
-            }
-        }
-    } else {
-        let msg = r#"Welcome to Nushell.
+        if rest.is_empty() && find.is_none() {
+            let msg = r#"Welcome to Nushell.
 
 Here are some tips to help you get started.
+  * help -h or help help - show available `help` subcommands and examples
   * help commands - list all available commands
-  * help <command name> - display help about a particular command
-  * help --find <text to search> - search through all of help
+  * help <name> - display help about a particular command, alias, or module
+  * help --find <text to search> - search through all help commands table
 
 Nushell works on the idea of a "pipeline". Pipelines are commands connected with the '|' character.
 Each stage in the pipeline works together to load, parse, and display information to you.
@@ -328,8 +82,111 @@ Get the processes on your system actively using CPU:
 
 You can also learn more at https://www.nushell.sh/book/"#;
 
-        Ok(Value::string(msg, head).into_pipeline_data())
+            Ok(Value::string(msg, head).into_pipeline_data())
+        } else if find.is_some() {
+            help_commands(engine_state, stack, call)
+        } else {
+            let result = help_commands(engine_state, stack, call);
+
+            let result = if let Err(ShellError::CommandNotFound(_)) = result {
+                help_aliases(engine_state, stack, call)
+            } else {
+                result
+            };
+
+            let result = if let Err(ShellError::AliasNotFound(_)) = result {
+                help_modules(engine_state, stack, call)
+            } else {
+                result
+            };
+
+            if let Err(ShellError::ModuleNotFoundAtRuntime(_, _)) = result {
+                let rest_spans: Vec<Span> = rest.iter().map(|arg| arg.span).collect();
+                Err(ShellError::NotFound(span(&rest_spans)))
+            } else {
+                result
+            }
+        }
     }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "show help for single command, alias, or module",
+                example: "help match",
+                result: None,
+            },
+            Example {
+                description: "show help for single sub-command, alias, or module",
+                example: "help str lpad",
+                result: None,
+            },
+            Example {
+                description: "search for string in command names, usage and search terms",
+                example: "help --find char",
+                result: None,
+            },
+        ]
+    }
+}
+
+pub fn highlight_search_in_table(
+    table: Vec<Value>, // list of records
+    search_string: &str,
+    searched_cols: &[&str],
+    string_style: &Style,
+) -> Result<Vec<Value>, ShellError> {
+    let orig_search_string = search_string;
+    let search_string = search_string.to_lowercase();
+    let mut matches = vec![];
+
+    for record in table {
+        let (cols, mut vals, record_span) = if let Value::Record { cols, vals, span } = record {
+            (cols, vals, span)
+        } else {
+            return Err(ShellError::NushellFailedSpanned(
+                "Expected record".to_string(),
+                format!("got {}", record.get_type()),
+                record.span()?,
+            ));
+        };
+
+        let has_match = cols.iter().zip(vals.iter_mut()).fold(
+            Ok(false),
+            |acc: Result<bool, ShellError>, (col, val)| {
+                if searched_cols.contains(&col.as_str()) {
+                    if let Value::String { val: s, span } = val {
+                        if s.to_lowercase().contains(&search_string) {
+                            *val = Value::String {
+                                val: highlight_search_string(s, orig_search_string, string_style)?,
+                                span: *span,
+                            };
+                            Ok(true)
+                        } else {
+                            // column does not contain the searched string
+                            acc
+                        }
+                    } else {
+                        // ignore non-string values
+                        acc
+                    }
+                } else {
+                    // don't search this column
+                    acc
+                }
+            },
+        )?;
+
+        if has_match {
+            matches.push(Value::Record {
+                cols,
+                vals,
+                span: record_span,
+            });
+        }
+    }
+
+    Ok(matches)
 }
 
 // Highlight the search string using ANSI escape sequences and regular expressions.

crates/nu-command/src/core_commands/help_aliases.rs

@@ -0,0 +1,181 @@
+use crate::help::highlight_search_in_table;
+use nu_color_config::StyleComputer;
+use nu_engine::{scope::ScopeData, CallExt};
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    span, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
+    ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
+};
+use std::borrow::Cow;
+
+#[derive(Clone)]
+pub struct HelpAliases;
+
+impl Command for HelpAliases {
+    fn name(&self) -> &str {
+        "help aliases"
+    }
+
+    fn usage(&self) -> &str {
+        "Show help on nushell aliases."
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("help aliases")
+            .category(Category::Core)
+            .rest(
+                "rest",
+                SyntaxShape::String,
+                "the name of alias to get help on",
+            )
+            .named(
+                "find",
+                SyntaxShape::String,
+                "string to find in alias names and usage",
+                Some('f'),
+            )
+            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "show all aliases",
+                example: "help aliases",
+                result: None,
+            },
+            Example {
+                description: "show help for single alias",
+                example: "help aliases my-alias",
+                result: None,
+            },
+            Example {
+                description: "search for string in alias names and usages",
+                example: "help aliases --find my-alias",
+                result: None,
+            },
+        ]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        help_aliases(engine_state, stack, call)
+    }
+}
+
+pub fn help_aliases(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+) -> Result<PipelineData, ShellError> {
+    let head = call.head;
+    let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
+    let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
+
+    // 🚩The following two-lines are copied from filters/find.rs:
+    let style_computer = StyleComputer::from_config(engine_state, stack);
+    // Currently, search results all use the same style.
+    // Also note that this sample string is passed into user-written code (the closure that may or may not be
+    // defined for "string").
+    let string_style = style_computer.compute("string", &Value::string("search result", head));
+
+    if let Some(f) = find {
+        let all_cmds_vec = build_help_aliases(engine_state, stack, head);
+        let found_cmds_vec =
+            highlight_search_in_table(all_cmds_vec, &f.item, &["name", "usage"], &string_style)?;
+
+        return Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()));
+    }
+
+    if rest.is_empty() {
+        let found_cmds_vec = build_help_aliases(engine_state, stack, head);
+
+        Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()))
+    } else {
+        let mut name = String::new();
+
+        for r in &rest {
+            if !name.is_empty() {
+                name.push(' ');
+            }
+            name.push_str(&r.item);
+        }
+
+        let alias_id = if let Some(id) = engine_state.find_alias(name.as_bytes(), &[]) {
+            id
+        } else {
+            return Err(ShellError::AliasNotFound(span(
+                &rest.iter().map(|r| r.span).collect::<Vec<Span>>(),
+            )));
+        };
+
+        let alias_expansion = engine_state
+            .get_alias(alias_id)
+            .iter()
+            .map(|span| String::from_utf8_lossy(engine_state.get_span_contents(span)))
+            .collect::<Vec<Cow<str>>>()
+            .join(" ");
+
+        let alias_usage = engine_state.build_alias_usage(alias_id);
+
+        // TODO: merge this into documentation.rs at some point
+        const G: &str = "\x1b[32m"; // green
+        const C: &str = "\x1b[36m"; // cyan
+        const RESET: &str = "\x1b[0m"; // reset
+
+        let mut long_desc = String::new();
+
+        if let Some((usage, extra_usage)) = alias_usage {
+            long_desc.push_str(&usage);
+            long_desc.push_str("\n\n");
+
+            if !extra_usage.is_empty() {
+                long_desc.push_str(&extra_usage);
+                long_desc.push_str("\n\n");
+            }
+        }
+
+        long_desc.push_str(&format!("{G}Alias{RESET}: {C}{name}{RESET}"));
+        long_desc.push_str("\n\n");
+        long_desc.push_str(&format!("{G}Expansion{RESET}:\n  {alias_expansion}"));
+
+        let config = engine_state.get_config();
+        if !config.use_ansi_coloring {
+            long_desc = nu_utils::strip_ansi_string_likely(long_desc);
+        }
+
+        Ok(Value::String {
+            val: long_desc,
+            span: call.head,
+        }
+        .into_pipeline_data())
+    }
+}
+
+fn build_help_aliases(engine_state: &EngineState, stack: &Stack, span: Span) -> Vec<Value> {
+    let mut scope_data = ScopeData::new(engine_state, stack);
+    scope_data.populate_aliases();
+
+    scope_data.collect_aliases(span)
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_examples() {
+        use super::HelpAliases;
+        use crate::test_examples;
+        test_examples(HelpAliases {})
+    }
+}

crates/nu-command/src/core_commands/help_commands.rs

@@ -0,0 +1,189 @@
+use crate::help::highlight_search_in_table;
+use nu_color_config::StyleComputer;
+use nu_engine::{get_full_help, CallExt};
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    span, Category, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
+    Signature, Span, Spanned, SyntaxShape, Type, Value,
+};
+use std::borrow::Borrow;
+
+#[derive(Clone)]
+pub struct HelpCommands;
+
+impl Command for HelpCommands {
+    fn name(&self) -> &str {
+        "help commands"
+    }
+
+    fn usage(&self) -> &str {
+        "Show help on nushell commands."
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("help commands")
+            .category(Category::Core)
+            .rest(
+                "rest",
+                SyntaxShape::String,
+                "the name of command to get help on",
+            )
+            .named(
+                "find",
+                SyntaxShape::String,
+                "string to find in command names, usage, and search terms",
+                Some('f'),
+            )
+            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        help_commands(engine_state, stack, call)
+    }
+}
+
+pub fn help_commands(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+) -> Result<PipelineData, ShellError> {
+    let head = call.head;
+    let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
+    let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
+
+    // 🚩The following two-lines are copied from filters/find.rs:
+    let style_computer = StyleComputer::from_config(engine_state, stack);
+    // Currently, search results all use the same style.
+    // Also note that this sample string is passed into user-written code (the closure that may or may not be
+    // defined for "string").
+    let string_style = style_computer.compute("string", &Value::string("search result", head));
+
+    if let Some(f) = find {
+        let all_cmds_vec = build_help_commands(engine_state, head);
+        let found_cmds_vec = highlight_search_in_table(
+            all_cmds_vec,
+            &f.item,
+            &["name", "usage", "search_terms"],
+            &string_style,
+        )?;
+
+        return Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()));
+    }
+
+    if rest.is_empty() {
+        let found_cmds_vec = build_help_commands(engine_state, head);
+
+        Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()))
+    } else {
+        let mut name = String::new();
+
+        for r in &rest {
+            if !name.is_empty() {
+                name.push(' ');
+            }
+            name.push_str(&r.item);
+        }
+
+        let output = engine_state
+            .get_signatures_with_examples(false)
+            .iter()
+            .filter(|(signature, _, _, _, _)| signature.name == name)
+            .map(|(signature, examples, _, _, is_parser_keyword)| {
+                get_full_help(signature, examples, engine_state, stack, *is_parser_keyword)
+            })
+            .collect::<Vec<String>>();
+
+        if !output.is_empty() {
+            Ok(Value::String {
+                val: output.join("======================\n\n"),
+                span: call.head,
+            }
+            .into_pipeline_data())
+        } else {
+            Err(ShellError::CommandNotFound(span(&[
+                rest[0].span,
+                rest[rest.len() - 1].span,
+            ])))
+        }
+    }
+}
+
+fn build_help_commands(engine_state: &EngineState, span: Span) -> Vec<Value> {
+    let commands = engine_state.get_decls_sorted(false);
+    let mut found_cmds_vec = Vec::new();
+
+    for (name_bytes, decl_id) in commands {
+        let mut cols = vec![];
+        let mut vals = vec![];
+
+        let name = String::from_utf8_lossy(&name_bytes).to_string();
+        let decl = engine_state.get_decl(decl_id);
+        let sig = decl.signature().update_from_command(name, decl.borrow());
+
+        let signatures = sig.to_string();
+        let key = sig.name;
+        let usage = sig.usage;
+        let search_terms = sig.search_terms;
+
+        cols.push("name".into());
+        vals.push(Value::String { val: key, span });
+
+        cols.push("category".into());
+        vals.push(Value::string(sig.category.to_string(), span));
+
+        cols.push("command_type".into());
+        vals.push(Value::String {
+            val: format!("{:?}", decl.command_type()).to_lowercase(),
+            span,
+        });
+
+        cols.push("usage".into());
+        vals.push(Value::String { val: usage, span });
+
+        cols.push("signatures".into());
+        vals.push(Value::String {
+            val: if decl.is_parser_keyword() {
+                "".to_string()
+            } else {
+                signatures
+            },
+            span,
+        });
+
+        cols.push("search_terms".into());
+        vals.push(if search_terms.is_empty() {
+            Value::nothing(span)
+        } else {
+            Value::String {
+                val: search_terms.join(", "),
+                span,
+            }
+        });
+
+        found_cmds_vec.push(Value::Record { cols, vals, span });
+    }
+
+    found_cmds_vec
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_examples() {
+        use super::HelpCommands;
+        use crate::test_examples;
+        test_examples(HelpCommands {})
+    }
+}

crates/nu-command/src/core_commands/help_modules.rs

@@ -0,0 +1,258 @@
+use crate::help::highlight_search_in_table;
+use nu_color_config::StyleComputer;
+use nu_engine::{scope::ScopeData, CallExt};
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    span, AliasId, Category, DeclId, Example, IntoInterruptiblePipelineData, IntoPipelineData,
+    PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
+};
+
+#[derive(Clone)]
+pub struct HelpModules;
+
+impl Command for HelpModules {
+    fn name(&self) -> &str {
+        "help modules"
+    }
+
+    fn usage(&self) -> &str {
+        "Show help on nushell modules."
+    }
+
+    fn extra_usage(&self) -> &str {
+        r#"When requesting help for a single module, its commands and aliases will be highlighted if they
+are also available in the current scope. Commands/aliases that were imported under a different name
+(such as with a prefix after `use some-module`) will be highlighted in parentheses."#
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("help modules")
+            .category(Category::Core)
+            .rest(
+                "rest",
+                SyntaxShape::String,
+                "the name of module to get help on",
+            )
+            .named(
+                "find",
+                SyntaxShape::String,
+                "string to find in module names and usage",
+                Some('f'),
+            )
+            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "show all modules",
+                example: "help modules",
+                result: None,
+            },
+            Example {
+                description: "show help for single module",
+                example: "help modules my-module",
+                result: None,
+            },
+            Example {
+                description: "search for string in module names and usages",
+                example: "help modules --find my-module",
+                result: None,
+            },
+        ]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        help_modules(engine_state, stack, call)
+    }
+}
+
+pub fn help_modules(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+) -> Result<PipelineData, ShellError> {
+    let head = call.head;
+    let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
+    let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
+
+    // 🚩The following two-lines are copied from filters/find.rs:
+    let style_computer = StyleComputer::from_config(engine_state, stack);
+    // Currently, search results all use the same style.
+    // Also note that this sample string is passed into user-written code (the closure that may or may not be
+    // defined for "string").
+    let string_style = style_computer.compute("string", &Value::string("search result", head));
+
+    if let Some(f) = find {
+        let all_cmds_vec = build_help_modules(engine_state, stack, head);
+        let found_cmds_vec =
+            highlight_search_in_table(all_cmds_vec, &f.item, &["name", "usage"], &string_style)?;
+
+        return Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()));
+    }
+
+    if rest.is_empty() {
+        let found_cmds_vec = build_help_modules(engine_state, stack, head);
+
+        Ok(found_cmds_vec
+            .into_iter()
+            .into_pipeline_data(engine_state.ctrlc.clone()))
+    } else {
+        let mut name = String::new();
+
+        for r in &rest {
+            if !name.is_empty() {
+                name.push(' ');
+            }
+            name.push_str(&r.item);
+        }
+
+        let module_id = if let Some(id) = engine_state.find_module(name.as_bytes(), &[]) {
+            id
+        } else {
+            return Err(ShellError::ModuleNotFoundAtRuntime(
+                name,
+                span(&rest.iter().map(|r| r.span).collect::<Vec<Span>>()),
+            ));
+        };
+
+        let module = engine_state.get_module(module_id);
+
+        let module_usage = engine_state.build_module_usage(module_id);
+
+        // TODO: merge this into documentation.rs at some point
+        const G: &str = "\x1b[32m"; // green
+        const C: &str = "\x1b[36m"; // cyan
+        const CB: &str = "\x1b[1;36m"; // cyan bold
+        const RESET: &str = "\x1b[0m"; // reset
+
+        let mut long_desc = String::new();
+
+        if let Some((usage, extra_usage)) = module_usage {
+            long_desc.push_str(&usage);
+            long_desc.push_str("\n\n");
+
+            if !extra_usage.is_empty() {
+                long_desc.push_str(&extra_usage);
+                long_desc.push_str("\n\n");
+            }
+        }
+
+        long_desc.push_str(&format!("{G}Module{RESET}: {C}{name}{RESET}"));
+        long_desc.push_str("\n\n");
+
+        if !module.decls.is_empty() {
+            let commands: Vec<(Vec<u8>, DeclId)> = engine_state.get_decls_sorted(false).collect();
+
+            let mut module_commands: Vec<(&[u8], DeclId)> = module
+                .decls
+                .iter()
+                .map(|(name, id)| (name.as_ref(), *id))
+                .collect();
+            module_commands.sort_by(|a, b| a.0.cmp(b.0));
+
+            let commands_str = module_commands
+                .iter()
+                .map(|(name_bytes, id)| {
+                    let name = String::from_utf8_lossy(name_bytes);
+                    if let Some((used_name_bytes, _)) =
+                        commands.iter().find(|(_, decl_id)| id == decl_id)
+                    {
+                        if engine_state.find_decl(name.as_bytes(), &[]).is_some() {
+                            format!("{CB}{name}{RESET}")
+                        } else {
+                            let command_name = String::from_utf8_lossy(used_name_bytes);
+                            format!("{name} ({CB}{command_name}{RESET})")
+                        }
+                    } else {
+                        format!("{name}")
+                    }
+                })
+                .collect::<Vec<String>>()
+                .join(", ");
+
+            long_desc.push_str(&format!("{G}Exported commands{RESET}:\n  {commands_str}"));
+            long_desc.push_str("\n\n");
+        }
+
+        if !module.aliases.is_empty() {
+            let aliases: Vec<(Vec<u8>, AliasId)> = engine_state.get_aliases_sorted(false).collect();
+
+            let mut module_aliases: Vec<(&[u8], AliasId)> = module
+                .aliases
+                .iter()
+                .map(|(name, id)| (name.as_ref(), *id))
+                .collect();
+            module_aliases.sort_by(|a, b| a.0.cmp(b.0));
+
+            let aliases_str = module_aliases
+                .iter()
+                .map(|(name_bytes, id)| {
+                    let name = String::from_utf8_lossy(name_bytes);
+                    if let Some((used_name_bytes, _)) =
+                        aliases.iter().find(|(_, alias_id)| id == alias_id)
+                    {
+                        if engine_state.find_alias(name.as_bytes(), &[]).is_some() {
+                            format!("{CB}{name}{RESET}")
+                        } else {
+                            let alias_name = String::from_utf8_lossy(used_name_bytes);
+                            format!("{name} ({CB}{alias_name}{RESET})")
+                        }
+                    } else {
+                        format!("{name}")
+                    }
+                })
+                .collect::<Vec<String>>()
+                .join(", ");
+
+            long_desc.push_str(&format!("{G}Exported aliases{RESET}:\n  {aliases_str}"));
+            long_desc.push_str("\n\n");
+        }
+
+        if module.env_block.is_some() {
+            long_desc.push_str(&format!("This module {C}exports{RESET} environment."));
+        } else {
+            long_desc.push_str(&format!(
+                "This module {C}does not export{RESET} environment."
+            ));
+        }
+
+        let config = engine_state.get_config();
+        if !config.use_ansi_coloring {
+            long_desc = nu_utils::strip_ansi_string_likely(long_desc);
+        }
+
+        Ok(Value::String {
+            val: long_desc,
+            span: call.head,
+        }
+        .into_pipeline_data())
+    }
+}
+
+fn build_help_modules(engine_state: &EngineState, stack: &Stack, span: Span) -> Vec<Value> {
+    let mut scope_data = ScopeData::new(engine_state, stack);
+    scope_data.populate_modules();
+
+    scope_data.collect_modules(span)
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_examples() {
+        use super::HelpModules;
+        use crate::test_examples;
+        test_examples(HelpModules {})
+    }
+}

crates/nu-command/src/core_commands/help_operators.rs

@@ -1,7 +1,7 @@
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Value,
+    Category, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,7 +17,10 @@ impl Command for HelpOperators {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("help operators").category(Category::Core)
+        Signature::build("help operators")
+            .category(Category::Core)
+            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
+            .allow_variants_without_examples(true)
     }
 
     fn run(

crates/nu-command/src/core_commands/hide.rs

@@ -1,8 +1,6 @@
-use nu_protocol::ast::{Call, Expr, Expression};
+use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
-};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type};
 
 #[derive(Clone)]
 pub struct Hide;
@@ -15,7 +13,12 @@ impl Command for Hide {
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("hide")
             .input_output_types(vec![(Type::Nothing, Type::Nothing)])
-            .required("pattern", SyntaxShape::ImportPattern, "import pattern")
+            .required("module", SyntaxShape::String, "Module or module file")
+            .optional(
+                "members",
+                SyntaxShape::Any,
+                "Which members of the module to import",
+            )
             .category(Category::Core)
     }
 
@@ -36,32 +39,11 @@ This command is a parser keyword. For details, check:
 
     fn run(
         &self,
-        engine_state: &EngineState,
-        stack: &mut Stack,
-        call: &Call,
+        _engine_state: &EngineState,
+        _stack: &mut Stack,
+        _call: &Call,
         _input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
-        let env_var_name = if let Some(Expression {
-            expr: Expr::ImportPattern(pat),
-            ..
-        }) = call.positional_nth(0)
-        {
-            Spanned {
-                item: String::from_utf8_lossy(&pat.head.name).to_string(),
-                span: pat.head.span,
-            }
-        } else {
-            return Err(ShellError::GenericError(
-                "Unexpected import".into(),
-                "import pattern not supported".into(),
-                Some(call.head),
-                None,
-                Vec::new(),
-            ));
-        };
-
-        stack.remove_env_var(engine_state, &env_var_name.item);
-
         Ok(PipelineData::empty())
     }
 
@@ -77,11 +59,6 @@ This command is a parser keyword. For details, check:
                 example: r#"def say-hi [] { echo 'Hi!' }; hide say-hi"#,
                 result: None,
             },
-            Example {
-                description: "Hide an environment variable",
-                example: r#"let-env HZ_ENV_ABC = 1; hide HZ_ENV_ABC; 'HZ_ENV_ABC' in (env).name"#,
-                result: Some(Value::boolean(false, Span::test_data())),
-            },
         ]
     }
 }

crates/nu-command/src/core_commands/hide_env.rs

@@ -2,8 +2,8 @@ use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    did_you_mean, Category, Example, PipelineData, ShellError, Signature, Span, Spanned,
-    SyntaxShape, Type, Value,
+    did_you_mean, Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape,
+    Type, Value,
 };
 
 #[derive(Clone)]
@@ -70,7 +70,7 @@ impl Command for HideEnv {
         vec![Example {
             description: "Hide an environment variable",
             example: r#"let-env HZ_ENV_ABC = 1; hide-env HZ_ENV_ABC; 'HZ_ENV_ABC' in (env).name"#,
-            result: Some(Value::boolean(false, Span::test_data())),
+            result: Some(Value::test_bool(false)),
         }]
     }
 }

crates/nu-command/src/core_commands/let_.rs

@@ -70,9 +70,8 @@ impl Command for Let {
         )?
         .0;
 
-        //println!("Adding: {:?} to {}", rhs, var_id);
-
         stack.add_var(var_id, rhs.into_value(call.head));
+
         Ok(PipelineData::empty())
     }
 

crates/nu-command/src/core_commands/loop_.rs

@@ -2,7 +2,7 @@ use nu_engine::{eval_block, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Block, Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -19,6 +19,8 @@ impl Command for Loop {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("loop")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required("block", SyntaxShape::Block, "block to loop")
             .category(Category::Core)
     }
@@ -79,7 +81,7 @@ impl Command for Loop {
         vec![Example {
             description: "Loop while a condition is true",
             example: "mut x = 0; loop { if $x > 10 { break }; $x = $x + 1 }; $x",
-            result: Some(Value::int(11, Span::test_data())),
+            result: Some(Value::test_int(11)),
         }]
     }
 }

crates/nu-command/src/core_commands/metadata.rs

@@ -106,7 +106,7 @@ impl Command for Metadata {
         vec![
             Example {
                 description: "Get the metadata of a variable",
-                example: "metadata $a",
+                example: "let a = 42; metadata $a",
                 result: None,
             },
             Example {

crates/nu-command/src/core_commands/mod.rs

@@ -2,6 +2,7 @@ mod alias;
 mod ast;
 mod break_;
 mod commandline;
+mod const_;
 mod continue_;
 mod debug;
 mod def;
@@ -19,6 +20,9 @@ mod export_use;
 mod extern_;
 mod for_;
 pub mod help;
+pub mod help_aliases;
+pub mod help_commands;
+pub mod help_modules;
 mod help_operators;
 mod hide;
 mod hide_env;
@@ -40,6 +44,7 @@ pub use alias::Alias;
 pub use ast::Ast;
 pub use break_::Break;
 pub use commandline::Commandline;
+pub use const_::Const;
 pub use continue_::Continue;
 pub use debug::Debug;
 pub use def::Def;
@@ -57,6 +62,9 @@ pub use export_use::ExportUse;
 pub use extern_::Extern;
 pub use for_::For;
 pub use help::Help;
+pub use help_aliases::HelpAliases;
+pub use help_commands::HelpCommands;
+pub use help_modules::HelpModules;
 pub use help_operators::HelpOperators;
 pub use hide::Hide;
 pub use hide_env::HideEnv;

crates/nu-command/src/core_commands/module.rs

@@ -1,6 +1,6 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
 
 #[derive(Clone)]
 pub struct Module;
@@ -46,17 +46,17 @@ impl Command for Module {
             Example {
                 description: "Define a custom command in a module and call it",
                 example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
-                result: Some(Value::string("foo", Span::test_data())),
+                result: Some(Value::test_string("foo")),
             },
             Example {
                 description: "Define an environment variable in a module",
                 example: r#"module foo { export-env { let-env FOO = "BAZ" } }; use foo; $env.FOO"#,
-                result: Some(Value::string("BAZ", Span::test_data())),
+                result: Some(Value::test_string("BAZ")),
             },
             Example {
                 description: "Define a custom command that participates in the environment in a module and call it",
                 example: r#"module foo { export def-env bar [] { let-env FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
-                result: Some(Value::string("BAZ", Span::test_data())),
+                result: Some(Value::test_string("BAZ")),
             },
         ]
     }

crates/nu-command/src/core_commands/overlay/command.rs

@@ -2,7 +2,7 @@ use nu_engine::get_full_help;
 use nu_protocol::{
     ast::Call,
     engine::{Command, EngineState, Stack},
-    Category, IntoPipelineData, PipelineData, Signature, Value,
+    Category, IntoPipelineData, PipelineData, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -14,7 +14,9 @@ impl Command for Overlay {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("overlay").category(Category::Core)
+        Signature::build("overlay")
+            .category(Category::Core)
+            .input_output_types(vec![(Type::Nothing, Type::String)])
     }
 
     fn usage(&self) -> &str {
@@ -23,7 +25,9 @@ impl Command for Overlay {
 
     fn extra_usage(&self) -> &str {
         r#"This command is a parser keyword. For details, check:
-  https://www.nushell.sh/book/thinking_in_nu.html"#
+  https://www.nushell.sh/book/thinking_in_nu.html
+  
+  You must use one of the following subcommands. Using this command as-is will only produce this help message."#
     }
 
     fn is_parser_keyword(&self) -> bool {
@@ -50,15 +54,3 @@ impl Command for Overlay {
         .into_pipeline_data())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(Overlay {})
-    }
-}

crates/nu-command/src/core_commands/overlay/hide.rs

@@ -1,7 +1,9 @@
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type,
+};
 
 #[derive(Clone)]
 pub struct OverlayHide;
@@ -17,6 +19,7 @@ impl Command for OverlayHide {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("overlay hide")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
             .optional("name", SyntaxShape::String, "Overlay to hide")
             .switch(
                 "keep-custom",

crates/nu-command/src/core_commands/overlay/list.rs

@@ -1,7 +1,7 @@
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Value,
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Type, Value,
 };
 
 #[derive(Clone)]
@@ -17,7 +17,9 @@ impl Command for OverlayList {
     }
 
     fn signature(&self) -> nu_protocol::Signature {
-        Signature::build("overlay list").category(Category::Core)
+        Signature::build("overlay list")
+            .category(Category::Core)
+            .input_output_types(vec![(Type::Nothing, Type::List(Box::new(Type::String)))])
     }
 
     fn extra_usage(&self) -> &str {
@@ -50,7 +52,7 @@ impl Command for OverlayList {
             example: r#"module spam { export def foo [] { "foo" } }
     overlay use spam
     overlay list | last"#,
-            result: Some(Value::string("spam", Span::test_data())),
+            result: Some(Value::test_string("spam")),
         }]
     }
 }

crates/nu-command/src/core_commands/overlay/new.rs

@@ -1,7 +1,9 @@
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type,
+};
 
 #[derive(Clone)]
 pub struct OverlayNew;
@@ -17,6 +19,8 @@ impl Command for OverlayNew {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("overlay new")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required("name", SyntaxShape::String, "Name of the overlay")
             // TODO:
             // .switch(

crates/nu-command/src/core_commands/overlay/use_.rs

@@ -3,7 +3,7 @@ use nu_parser::trim_quotes_str;
 use nu_protocol::ast::{Call, Expr};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Value,
+    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type, Value,
 };
 
 use std::path::Path;
@@ -22,6 +22,8 @@ impl Command for OverlayUse {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("overlay use")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required(
                 "name",
                 SyntaxShape::String,
@@ -64,7 +66,7 @@ impl Command for OverlayUse {
         let mut name_arg: Spanned<String> = call.req(engine_state, caller_stack, 0)?;
         name_arg.item = trim_quotes_str(&name_arg.item).to_string();
 
-        let maybe_origin_module_id = if let Some(overlay_expr) = call.positional_nth(0) {
+        let maybe_origin_module_id = if let Some(overlay_expr) = call.parser_info_nth(0) {
             if let Expr::Overlay(module_id) = overlay_expr.expr {
                 module_id
             } else {
@@ -82,25 +84,8 @@ impl Command for OverlayUse {
             ));
         };
 
-        let overlay_name = if let Some(kw_expression) = call.positional_nth(1) {
-            // If renamed via the 'as' keyword, use the new name as the overlay name
-            if let Some(new_name_expression) = kw_expression.as_keyword() {
-                if let Some(new_name) = new_name_expression.as_string() {
-                    new_name
-                } else {
-                    return Err(ShellError::NushellFailedSpanned(
-                        "Wrong keyword type".to_string(),
-                        "keyword argument not a string".to_string(),
-                        new_name_expression.span,
-                    ));
-                }
-            } else {
-                return Err(ShellError::NushellFailedSpanned(
-                    "Wrong keyword type".to_string(),
-                    "keyword argument not a keyword".to_string(),
-                    kw_expression.span,
-                ));
-            }
+        let overlay_name = if let Some(name) = call.opt(engine_state, caller_stack, 1)? {
+            name
         } else if engine_state
             .find_overlay(name_arg.item.as_bytes())
             .is_some()

crates/nu-command/src/core_commands/try_.rs

@@ -1,7 +1,9 @@
 use nu_engine::{eval_block, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Block, Closure, Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Type, Value};
+use nu_protocol::{
+    Category, Example, IntoPipelineData, PipelineData, Signature, SyntaxShape, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct Try;
@@ -55,13 +57,20 @@ impl Command for Try {
 
         match result {
             Err(error) | Ok(PipelineData::Value(Value::Error { error }, ..)) => {
+                if let nu_protocol::ShellError::Break(_) = error {
+                    return Err(error);
+                } else if let nu_protocol::ShellError::Continue(_) = error {
+                    return Err(error);
+                } else if let nu_protocol::ShellError::Return(_, _) = error {
+                    return Err(error);
+                }
                 if let Some(catch_block) = catch_block {
                     let catch_block = engine_state.get_block(catch_block.block_id);
-
+                    let err_value = Value::Error { error };
+                    // Put the error value in the positional closure var
                     if let Some(var) = catch_block.signature.get_positional(0) {
                         if let Some(var_id) = &var.var_id {
-                            let err_value = Value::Error { error };
-                            stack.add_var(*var_id, err_value);
+                            stack.add_var(*var_id, err_value.clone());
                         }
                     }
 
@@ -69,7 +78,8 @@ impl Command for Try {
                         engine_state,
                         stack,
                         catch_block,
-                        PipelineData::empty(),
+                        // Make the error accessible with $in, too
+                        err_value.into_pipeline_data(),
                         false,
                         false,
                     )
@@ -86,6 +96,9 @@ impl Command for Try {
 
                         if let Some(var) = catch_block.signature.get_positional(0) {
                             if let Some(var_id) = &var.var_id {
+                                // Because external command errors aren't "real" errors,
+                                // (unless do -c is in effect)
+                                // they can't be passed in as Nushell values.
                                 let err_value = Value::nothing(call.head);
                                 stack.add_var(*var_id, err_value);
                             }
@@ -95,7 +108,8 @@ impl Command for Try {
                             engine_state,
                             stack,
                             catch_block,
-                            PipelineData::empty(),
+                            // The same null as in the above block is set as the $in value.
+                            Value::nothing(call.head).into_pipeline_data(),
                             false,
                             false,
                         )

crates/nu-command/src/core_commands/use_.rs

@@ -2,7 +2,7 @@ use nu_engine::{eval_block, find_in_dirs_env, redirect_env};
 use nu_protocol::ast::{Call, Expr, Expression};
 use nu_protocol::engine::{Command, EngineState, Stack};
 use nu_protocol::{
-    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -20,7 +20,12 @@ impl Command for Use {
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("use")
             .input_output_types(vec![(Type::Nothing, Type::Nothing)])
-            .required("pattern", SyntaxShape::ImportPattern, "import pattern")
+            .required("module", SyntaxShape::String, "Module or module file")
+            .optional(
+                "members",
+                SyntaxShape::Any,
+                "Which members of the module to import",
+            )
             .category(Category::Core)
     }
 
@@ -43,7 +48,7 @@ impl Command for Use {
         let import_pattern = if let Some(Expression {
             expr: Expr::ImportPattern(pat),
             ..
-        }) = call.positional_nth(0)
+        }) = call.parser_info_nth(0)
         {
             pat
         } else {
@@ -117,12 +122,12 @@ impl Command for Use {
             Example {
                 description: "Define a custom command in a module and call it",
                 example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
-                result: Some(Value::string("foo", Span::test_data())),
+                result: Some(Value::test_string("foo")),
             },
             Example {
                 description: "Define a custom command that participates in the environment in a module and call it",
                 example: r#"module foo { export def-env bar [] { let-env FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
-                result: Some(Value::string("BAZ", Span::test_data())),
+                result: Some(Value::test_string("BAZ")),
             },
         ]
     }

crates/nu-command/src/core_commands/while_.rs

@@ -1,7 +1,9 @@
 use nu_engine::{eval_block, eval_expression, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Block, Command, EngineState, Stack};
-use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Value};
+use nu_protocol::{
+    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
+};
 
 #[derive(Clone)]
 pub struct While;
@@ -17,6 +19,8 @@ impl Command for While {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("while")
+            .input_output_types(vec![(Type::Nothing, Type::Nothing)])
+            .allow_variants_without_examples(true)
             .required("cond", SyntaxShape::Expression, "condition to check")
             .required(
                 "block",

crates/nu-command/src/database/commands/into_sqlite.rs

@@ -20,6 +20,9 @@ impl Command for IntoSqliteDb {
 
     fn signature(&self) -> Signature {
         Signature::build("into sqlite")
+            .input_output_types(vec![(Type::Any, Type::Nothing)])
+            .allow_variants_without_examples(true)
+            // TODO: narrow disallowed types
             .required(
                 "file_name",
                 SyntaxShape::String,
@@ -215,12 +218,14 @@ fn action(
             // and we're done
             Ok(Value::Nothing { span: *span })
         }
-        _ => Err(ShellError::UnsupportedInput(
-            format!(
-                "Expected a list but instead received a {}",
-                input.get_type()
-            ),
+        // Propagate errors by explicitly matching them before the final case.
+        Value::Error { error } => Err(error.clone()),
+        other => Err(ShellError::OnlySupportsThisInputType(
+            "list".into(),
+            other.get_type().to_string(),
             span,
+            // This line requires the Value::Error match above.
+            other.expect_span(),
         )),
     }
 }

crates/nu-command/src/database/commands/query_db.rs

@@ -18,6 +18,7 @@ impl Command for QueryDb {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .required(
                 "SQL",
                 SyntaxShape::String,

crates/nu-command/src/database/commands/schema.rs

@@ -16,6 +16,7 @@ impl Command for SchemaDb {
 
     fn signature(&self) -> Signature {
         Signature::build(self.name())
+            .input_output_types(vec![(Type::Any, Type::Any)])
             .input_type(Type::Any)
             .output_type(Type::Any)
             .category(Category::Custom("database".into()))

crates/nu-command/src/dataframe/eager/columns.rs

@@ -29,10 +29,7 @@ impl Command for ColumnsDF {
             description: "Dataframe columns",
             example: "[[a b]; [1 2] [3 4]] | into df | columns",
             result: Some(Value::List {
-                vals: vec![
-                    Value::string("a", Span::test_data()),
-                    Value::string("b", Span::test_data()),
-                ],
+                vals: vec![Value::test_string("a"), Value::test_string("b")],
                 span: Span::test_data(),
             }),
         }]

crates/nu-command/src/dataframe/eager/drop.rs

@@ -70,7 +70,7 @@ fn command(
         .ok_or_else(|| {
             ShellError::GenericError(
                 "Empty names list".into(),
-                "No column names where found".into(),
+                "No column names were found".into(),
                 Some(col_span),
                 None,
                 Vec::new(),

crates/nu-command/src/dataframe/eager/mod.rs

@@ -30,6 +30,7 @@ mod with_column;
 
 use nu_protocol::engine::StateWorkingSet;
 
+pub use self::open::OpenDataFrame;
 pub use append::AppendDF;
 pub use columns::ColumnsDF;
 pub use drop::DropDF;
@@ -43,7 +44,6 @@ pub use get::GetDF;
 pub use last::LastDF;
 pub use list::ListDF;
 pub use melt::MeltDF;
-pub use open::OpenDataFrame;
 pub use query_df::QueryDf;
 pub use rename::RenameDF;
 pub use sample::SampleDF;

crates/nu-command/src/dataframe/expressions/as_nu.rs

@@ -31,10 +31,7 @@ impl Command for ExprAsNu {
             example: "col a | into nu",
             result: Some(Value::Record {
                 cols: vec!["expr".into(), "value".into()],
-                vals: vec![
-                    Value::string("column", Span::test_data()),
-                    Value::string("a", Span::test_data()),
-                ],
+                vals: vec![Value::test_string("column"), Value::test_string("a")],
                 span: Span::test_data(),
             }),
         }]

crates/nu-command/src/dataframe/expressions/col.rs

@@ -37,10 +37,7 @@ impl Command for ExprCol {
             example: "col a | into nu",
             result: Some(Value::Record {
                 cols: vec!["expr".into(), "value".into()],
-                vals: vec![
-                    Value::string("column", Span::test_data()),
-                    Value::string("a", Span::test_data()),
-                ],
+                vals: vec![Value::test_string("column"), Value::test_string("a")],
                 span: Span::test_data(),
             }),
         }]

crates/nu-command/src/dataframe/expressions/lit.rs

@@ -36,10 +36,7 @@ impl Command for ExprLit {
             example: "lit 2 | into nu",
             result: Some(Value::Record {
                 cols: vec!["expr".into(), "value".into()],
-                vals: vec![
-                    Value::string("literal", Span::test_data()),
-                    Value::string("2i64", Span::test_data()),
-                ],
+                vals: vec![Value::test_string("literal"), Value::test_string("2i64")],
                 span: Span::test_data(),
             }),
         }]

crates/nu-command/src/dataframe/lazy/fill_na.rs

@@ -1,68 +0,0 @@
-use crate::dataframe::values::{NuExpression, NuLazyFrame};
-use nu_engine::CallExt;
-use nu_protocol::{
-    ast::Call,
-    engine::{Command, EngineState, Stack},
-    Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
-};
-
-#[derive(Clone)]
-pub struct LazyFillNA;
-
-impl Command for LazyFillNA {
-    fn name(&self) -> &str {
-        "fill-na"
-    }
-
-    fn usage(&self) -> &str {
-        "Replaces NA values with the given expression"
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build(self.name())
-            .required(
-                "fill",
-                SyntaxShape::Any,
-                "Expression to use to fill the NAN values",
-            )
-            .input_type(Type::Custom("dataframe".into()))
-            .output_type(Type::Custom("dataframe".into()))
-            .category(Category::Custom("lazyframe".into()))
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "",
-            example: "",
-            result: None,
-        }]
-    }
-
-    fn run(
-        &self,
-        engine_state: &EngineState,
-        stack: &mut Stack,
-        call: &Call,
-        input: PipelineData,
-    ) -> Result<PipelineData, ShellError> {
-        let fill: Value = call.req(engine_state, stack, 0)?;
-        let value = input.into_value(call.head);
-
-        if NuExpression::can_downcast(&value) {
-            let expr = NuExpression::try_from_value(value)?;
-            let fill = NuExpression::try_from_value(fill)?.into_polars();
-            let expr: NuExpression = expr.into_polars().fill_nan(fill).into();
-
-            Ok(PipelineData::Value(
-                NuExpression::into_value(expr, call.head),
-                None,
-            ))
-        } else {
-            let lazy = NuLazyFrame::try_from_value(value)?;
-            let expr = NuExpression::try_from_value(fill)?.into_polars();
-            let lazy = NuLazyFrame::new(lazy.from_eager, lazy.into_polars().fill_nan(expr));
-
-            Ok(PipelineData::Value(lazy.into_value(call.head)?, None))
-        }
-    }
-}

crates/nu-command/src/dataframe/lazy/fill_nan.rs

@@ -0,0 +1,137 @@
+use crate::dataframe::values::{Column, NuDataFrame, NuExpression};
+use nu_engine::CallExt;
+use nu_protocol::{
+    ast::Call,
+    engine::{Command, EngineState, Stack},
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
+};
+
+#[derive(Clone)]
+pub struct LazyFillNA;
+
+impl Command for LazyFillNA {
+    fn name(&self) -> &str {
+        "fill-nan"
+    }
+
+    fn usage(&self) -> &str {
+        "Replaces NaN values with the given expression"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build(self.name())
+            .required(
+                "fill",
+                SyntaxShape::Any,
+                "Expression to use to fill the NAN values",
+            )
+            .input_type(Type::Custom("dataframe".into()))
+            .output_type(Type::Custom("dataframe".into()))
+            .category(Category::Custom("lazyframe".into()))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Fills the NaN values with 0",
+                example: "[1 2 NaN 3 NaN] | into df | fill-nan 0",
+                result: Some(
+                    NuDataFrame::try_from_columns(vec![Column::new(
+                        "0".to_string(),
+                        vec![
+                            Value::test_int(1),
+                            Value::test_int(2),
+                            Value::test_int(0),
+                            Value::test_int(3),
+                            Value::test_int(0),
+                        ],
+                    )])
+                    .expect("Df for test should not fail")
+                    .into_value(Span::test_data()),
+                ),
+            },
+            Example {
+                description: "Fills the NaN values of a whole dataframe",
+                example: "[[a b]; [0.2 1] [0.1 NaN]] | into df | fill-nan 0",
+                result: Some(
+                    NuDataFrame::try_from_columns(vec![
+                        Column::new(
+                            "a".to_string(),
+                            vec![Value::test_float(0.2), Value::test_float(0.1)],
+                        ),
+                        Column::new(
+                            "b".to_string(),
+                            vec![Value::test_int(1), Value::test_int(0)],
+                        ),
+                    ])
+                    .expect("Df for test should not fail")
+                    .into_value(Span::test_data()),
+                ),
+            },
+        ]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let fill: Value = call.req(engine_state, stack, 0)?;
+        let value = input.into_value(call.head);
+
+        if NuExpression::can_downcast(&value) {
+            let expr = NuExpression::try_from_value(value)?;
+            let fill = NuExpression::try_from_value(fill)?.into_polars();
+            let expr: NuExpression = expr.into_polars().fill_nan(fill).into();
+
+            Ok(PipelineData::Value(
+                NuExpression::into_value(expr, call.head),
+                None,
+            ))
+        } else {
+            let val_span = value.span()?;
+            let frame = NuDataFrame::try_from_value(value)?;
+            let columns = frame.columns(val_span)?;
+            let dataframe = columns
+                .into_iter()
+                .map(|column| {
+                    let column_name = column.name().to_string();
+                    let values = column
+                        .into_iter()
+                        .map(|value| match value {
+                            Value::Float { val, .. } => {
+                                if val.is_nan() {
+                                    fill.clone()
+                                } else {
+                                    value
+                                }
+                            }
+                            Value::List { vals, span } => {
+                                NuDataFrame::fill_list_nan(vals, span, fill.clone())
+                            }
+                            _ => value,
+                        })
+                        .collect::<Vec<Value>>();
+                    Column::new(column_name, values)
+                })
+                .collect::<Vec<Column>>();
+            Ok(PipelineData::Value(
+                NuDataFrame::try_from_columns(dataframe)?.into_value(call.head),
+                None,
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::super::super::test_dataframe::test_dataframe;
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        test_dataframe(vec![Box::new(LazyFillNA {})])
+    }
+}