Rework sorting and add cell path and closure comparators to sort-by (#13154)

# Description

Closes #12535
Implements sort-by functionality of #8322
Fixes sort-by part of #8667

This PR does two main things: add a new cell path and closure parameter
to `sort-by`, and attempt to make Nushell's sorting behavior
well-defined.

## `sort-by` features

The `columns` parameter is replaced with a `comparator` parameter, which
can be a cell path or a closure. Examples are from docs PR.

1. Cell paths

The basic interactive usage of `sort-by` is the same. For example, `ls |
sort-by modified` still works the same as before. It is not quite a
drop-in replacement, see [behavior changes](#behavior-changes).
   
   Here's an example of how the cell path comparator might be useful:
   
   ```nu
   > let cities = [
{name: 'New York', info: { established: 1624, population: 18_819_000 } }
{name: 'Kyoto', info: { established: 794, population: 37_468_000 } }
{name: 'São Paulo', info: { established: 1554, population: 21_650_000 }
}
   ]
   > $cities | sort-by info.established
   ╭───┬───────────┬────────────────────────────╮
   │ # │   name    │            info            │
   ├───┼───────────┼────────────────────────────┤
   │ 0 │ Kyoto     │ ╭─────────────┬──────────╮ │
   │   │           │ │ established │ 794      │ │
   │   │           │ │ population  │ 37468000 │ │
   │   │           │ ╰─────────────┴──────────╯ │
   │ 1 │ São Paulo │ ╭─────────────┬──────────╮ │
   │   │           │ │ established │ 1554     │ │
   │   │           │ │ population  │ 21650000 │ │
   │   │           │ ╰─────────────┴──────────╯ │
   │ 2 │ New York  │ ╭─────────────┬──────────╮ │
   │   │           │ │ established │ 1624     │ │
   │   │           │ │ population  │ 18819000 │ │
   │   │           │ ╰─────────────┴──────────╯ │
   ╰───┴───────────┴────────────────────────────╯
   ```

2. Key closures

You can supply a closure which will transform each value into a sorting
key (without changing the underlying data). Here's an example of a key
closure, where we want to sort a list of assignments by their average
grade:

   ```nu
   > let assignments = [
       {name: 'Homework 1', grades: [97 89 86 92 89] }
       {name: 'Homework 2', grades: [91 100 60 82 91] }
       {name: 'Exam 1', grades: [78 88 78 53 90] }
       {name: 'Project', grades: [92 81 82 84 83] }
   ]
   > $assignments | sort-by { get grades | math avg }
   ╭───┬────────────┬───────────────────────╮
   │ # │    name    │        grades         │
   ├───┼────────────┼───────────────────────┤
   │ 0 │ Exam 1     │ [78, 88, 78, 53, 90]  │
   │ 1 │ Project    │ [92, 81, 82, 84, 83]  │
   │ 2 │ Homework 2 │ [91, 100, 60, 82, 91] │
   │ 3 │ Homework 1 │ [97, 89, 86, 92, 89]  │
   ╰───┴────────────┴───────────────────────╯
   ```

3. Custom sort closure

The `--custom`, or `-c`, flag will tell `sort-by` to interpret closures
as custom sort closures. A custom sort closure has two parameters, and
returns a boolean. The closure should return `true` if the first
parameter comes _before_ the second parameter in the sort order.
   
For a simple example, we could rewrite a cell path sort as a custom sort
(see
[here](https://github.com/nushell/nushell.github.io/pull/1568/files#diff-a7a233e66a361d8665caf3887eb71d4288000001f401670c72b95cc23a948e86R231)
for a more complex example):
   
   ```nu
   > ls | sort-by -c {|a, b| $a.size < $b.size }
   ╭───┬─────────────────────┬──────┬──────────┬────────────────╮
   │ # │        name         │ type │   size   │    modified    │
   ├───┼─────────────────────┼──────┼──────────┼────────────────┤
   │ 0 │ my-secret-plans.txt │ file │    100 B │ 10 minutes ago │
   │ 1 │ shopping_list.txt   │ file │    100 B │ 2 months ago   │
   │ 2 │ myscript.nu         │ file │  1.1 KiB │ 2 weeks ago    │
   │ 3 │ bigfile.img         │ file │ 10.0 MiB │ 3 weeks ago    │
   ╰───┴─────────────────────┴──────┴──────────┴────────────────╯
   ```
   

## Making sort more consistent

I think it's important for something as essential as `sort` to have
well-defined semantics. This PR contains some changes to try to make the
behavior of `sort` and `sort-by` consistent. In addition, after working
with the internals of sorting code, I have a much deeper understanding
of all of the edge cases. Here is my attempt to try to better define
some of the semantics of sorting (if you are just interested in changes,
skip to "User-Facing changes")

- `sort`, `sort -v`, and `sort-by` now all work the same. Each
individual sort implementation has been refactored into two functions in
`sort_utils.rs`: `sort`, and `sort_by`. These can also be used in other
parts of Nushell where values need to be sorted.
  - `sort` and `sort-by` used to handle `-i` and `-n` differently.
- `sort -n` would consider all values which can't be coerced into a
string to be equal
- `sort-by -i` and `sort-by -n` would only work if all values were
strings
- In this PR, insensitive sort only affects comparison between strings,
and natural sort only applies to numbers and strings (see below).
- (not a change) Before and after this PR, `sort` and `sort-by` support
sorting mixed types. There was a lot of discussion about potentially
making `sort` and `sort-by` only work on lists of homogeneous types, but
the general consensus was that `sort` should not error just because its
input contains incompatible types.
- In order to try to make working with data containing `null` values
easier, I changed the PartialOrd order to sort `Nothing` values to the
end of a list, regardless of what other types the list contains. Before,
`null` would be sorted before `Binary`, `CellPath`, and `Custom` values.
- (not a change) When sorted, lists of mixed types will contain sorted
values of each type in order, for the most part
- (not a change) For example, `[0x[1] (date now) "a" ("yesterday" | into
datetime) "b" 0x[0]]` will be sorted as `["a", "b", a day ago, now, [0],
[1]]`, where sorted strings appear first, then sorted datetimes, etc.
- (not a change) The exception to this is `Int`s and `Float`s, which
will intermix, `Strings` and `Glob`s, which will intermix, and `None` as
described above. Additionally, natural sort will intermix strings with
ints and floats (see below).
- Natural sort no longer coerce all inputs to strings.
- I did originally make natural only apply to strings, but @fdncred
pointed out that the previous behavior also allowed you to sort numeric
strings with numbers. This seems like a useful feature if we are trying
to support sorting with mixed types, so I settled on coercing only
numbers (int, float). This can be reverted if people don't like it.
- Here is an example of this behavior in action, which is the same
before and after this PR:
      ```nushell
      $ [1 "4" 3 "2"] | sort --natural
      ╭───┬───╮
      │ 0 │ 1 │
      │ 1 │ 2 │
      │ 2 │ 3 │
      │ 3 │ 4 │
      ╰───┴───╯
      ```



# User-Facing Changes

## New features

- Replaces the `columns` string parameter of `sort-by` with a cell path
or a closure.
  - The cell path parameter works exactly as you would expect
- By default, the `closure` parameter acts as a "key sort"; that is,
each element is transformed by the closure into a sorting key
- With the `--custom` (`-c`) parameter, you can define a comparison
function for completely custom sorting order.

## Behavior changes

<details>
<summary><code>sort -v</code> does not coerce record values to
strings</summary>

This was a bit of a surprising behavior, and is now unified with the
behavior of `sort` and `sort-by`. Here's an example where you can
observe the values being implicitly coerced into strings for sorting, as
they are sorted like strings rather than numbers:

Old behavior:

```nushell
$ {foo: 9 bar: 10} | sort -v
╭─────┬────╮
│ bar │ 10 │
│ foo │ 9  │
╰─────┴────╯
```

New behavior:

```nushell
$ {foo: 9 bar: 10} | sort -v
╭─────┬────╮
│ foo │ 9  │
│ bar │ 10 │
╰─────┴────╯
```

</details>


<details>
<summary>Changed <code>sort-by</code> parameters from
<code>string</code> to <code>cell-path</code> or <code>closure</code>.
Typical interactive usage is the same as before, but if passing a
variable to <code>sort-by</code> it must be a cell path (or closure),
not a string</summary>

Old behavior:

```nushell
$ let sort = "modified"
$ ls | sort-by $sort
╭───┬──────┬──────┬──────┬────────────────╮
│ # │ name │ type │ size │    modified    │
├───┼──────┼──────┼──────┼────────────────┤
│ 0 │ foo  │ file │  0 B │ 10 hours ago   │
│ 1 │ bar  │ file │  0 B │ 35 seconds ago │
╰───┴──────┴──────┴──────┴────────────────╯
```

New behavior:

```nushell
$ let sort = "modified"
$ ls | sort-by $sort
Error: nu:🐚:type_mismatch

  × Type mismatch.
   ╭─[entry #10:1:14]
 1 │ ls | sort-by $sort
   ·              ──┬──
   ·                ╰── Cannot sort using a value which is not a cell path or closure
   ╰────
$ let sort = $."modified"
$ ls | sort-by $sort
╭───┬──────┬──────┬──────┬───────────────╮
│ # │ name │ type │ size │   modified    │
├───┼──────┼──────┼──────┼───────────────┤
│ 0 │ foo  │ file │  0 B │ 10 hours ago  │
│ 1 │ bar  │ file │  0 B │ 2 minutes ago │
╰───┴──────┴──────┴──────┴───────────────╯
```
</details>

<details>
<summary>Insensitve and natural sorting behavior reworked</summary>

Previously, the `-i` and `-n` worked differently for `sort` and
`sort-by` (see "Making sort more consistent"). Here are examples of how
these options result in different sorts now:

1. `sort -n`
- Old behavior (types other than numbers, strings, dates, and binary
sorted incorrectly)
      ```nushell
      $ [2sec 1sec] | sort -n
      ╭───┬──────╮
      │ 0 │ 2sec │
      │ 1 │ 1sec │
      ╰───┴──────╯
      ```
    - New behavior
      ```nushell
      $ [2sec 1sec] | sort -n
      ╭───┬──────╮
      │ 0 │ 1sec │
      │ 1 │ 2sec │
      ╰───┴──────╯
      ```
    
2. `sort-by -i`
- Old behavior (uppercase words appear before lowercase words as they
would in a typical sort, indicating this is not actually an insensitive
sort)
     ```nushell
     $ ["BAR" "bar" "foo" 2 "FOO" 1] | wrap a | sort-by -i a
     ╭───┬─────╮
     │ # │  a  │
     ├───┼─────┤
     │ 0 │   1 │
     │ 1 │   2 │
     │ 2 │ BAR │
     │ 3 │ FOO │
     │ 4 │ bar │
     │ 5 │ foo │
     ╰───┴─────╯
     ```
- New behavior (strings are sorted stably, indicating this is an
insensitive sort)
     ```nushell
     $ ["BAR" "bar" "foo" 2 "FOO" 1] | wrap a | sort-by -i a
     ╭───┬─────╮
     │ # │  a  │
     ├───┼─────┤
     │ 0 │   1 │
     │ 1 │   2 │
     │ 2 │ BAR │
     │ 3 │ bar │
     │ 4 │ foo │
     │ 5 │ FOO │
     ╰───┴─────╯
     ```

3. `sort-by -n`
- Old behavior (natural sort does not work when data contains non-string
values)
     ```nushell
     $ ["10" 8 "9"] | wrap a | sort-by -n a
     ╭───┬────╮
     │ # │ a  │
     ├───┼────┤
     │ 0 │  8 │
     │ 1 │ 10 │
     │ 2 │ 9  │
     ╰───┴────╯
     ```
   - New behavior
     ```nushell
     $ ["10" 8 "9"] | wrap a | sort-by -n a
     ╭───┬────╮
     │ # │ a  │
     ├───┼────┤
     │ 0 │  8 │
     │ 1 │ 9  │
     │ 2 │ 10 │
     ╰───┴────╯
     ```

</details>

<details>
<summary>
Sorting a list of non-record values with a non-existent column/path now
errors instead of sorting the values directly (<code>sort</code> should
be used for this, not <code>sort-by</code>)
</summary>

Old behavior:

```nushell
$ [2 1] | sort-by foo
╭───┬───╮
│ 0 │ 1 │
│ 1 │ 2 │
╰───┴───╯
```

New behavior:

```nushell
$ [2 1] | sort-by foo
Error: nu:🐚:incompatible_path_access

  × Data cannot be accessed with a cell path
   ╭─[entry #29:1:17]
 1 │ [2 1] | sort-by foo
   ·                 ─┬─
   ·                  ╰── int doesn't support cell paths
   ╰────
```

</details>

<details>
<summary><code>sort</code> and <code>sort-by</code> output
<code>List</code> instead of <code>ListStream</code> </summary>

This isn't a meaningful change (unless I misunderstand the purpose of
ListStream), since `sort` and `sort-by` both need to collect in order to
do the sorting anyway, but is user observable.

Old behavior:

```nushell
$ ls | sort | describe -d
╭──────────┬───────────────────╮
│ type     │ stream            │
│ origin   │ nushell           │
│ subtype  │ {record 3 fields} │
│ metadata │ {record 1 field}  │
╰──────────┴───────────────────╯
```

```nushell
$ ls | sort-by name | describe -d
╭──────────┬───────────────────╮
│ type     │ stream            │
│ origin   │ nushell           │
│ subtype  │ {record 3 fields} │
│ metadata │ {record 1 field}  │
╰──────────┴───────────────────╯
```

New behavior:


```nushell
ls | sort | describe -d
╭────────┬─────────────────╮
│ type   │ list            │
│ length │ 22              │
│ values │ [table 22 rows] │
╰────────┴─────────────────╯
```

```nushell
$ ls | sort-by name | describe -d
╭────────┬─────────────────╮
│ type   │ list            │
│ length │ 22              │
│ values │ [table 22 rows] │
╰────────┴─────────────────╯
```

</details>

- `sort` now errors when nothing is piped in (`sort-by` already did
this)

# Tests + Formatting

I added lots of unit tests on the new sort implementation to enforce new
sort behaviors and prevent regressions.

# After Submitting

See [docs PR](https://github.com/nushell/nushell.github.io/pull/1568),
which is ~2/3 finished.

---------

Co-authored-by: NotTheDr01ds <32344964+NotTheDr01ds@users.noreply.github.com>
Co-authored-by: Ian Manske <ian.manske@pm.me>

crates/nu-command/src/filters/sort.rs

@@ -1,8 +1,7 @@
-use alphanumeric_sort::compare_str;
 use nu_engine::command_prelude::*;
+use nu_protocol::ast::PathMember;
 
-use nu_utils::IgnoreCaseExt;
-use std::cmp::Ordering;
+use crate::Comparator;
 
 #[derive(Clone)]
 pub struct Sort;
@@ -14,10 +13,13 @@ impl Command for Sort {
 
     fn signature(&self) -> nu_protocol::Signature {
         Signature::build("sort")
-        .input_output_types(vec![(
-            Type::List(Box::new(Type::Any)),
-            Type::List(Box::new(Type::Any)),
-        ), (Type::record(), Type::record()),])
+            .input_output_types(vec![
+                (
+                    Type::List(Box::new(Type::Any)),
+                    Type::List(Box::new(Type::Any))
+                ),
+                (Type::record(), Type::record())
+            ])
     .switch("reverse", "Sort in reverse order", Some('r'))
             .switch(
                 "ignore-case",
@@ -45,67 +47,66 @@ impl Command for Sort {
         vec![
             Example {
                 example: "[2 0 1] | sort",
-                description: "sort the list by increasing value",
-                result: Some(Value::list(
-                    vec![Value::test_int(0), Value::test_int(1), Value::test_int(2)],
-                    Span::test_data(),
-                )),
+                description: "Sort the list by increasing value",
+                result: Some(Value::test_list(vec![
+                    Value::test_int(0),
+                    Value::test_int(1),
+                    Value::test_int(2),
+                ])),
             },
             Example {
                 example: "[2 0 1] | sort --reverse",
-                description: "sort the list by decreasing value",
-                result: Some(Value::list(
-                    vec![Value::test_int(2), Value::test_int(1), Value::test_int(0)],
-                    Span::test_data(),
-                )),
+                description: "Sort the list by decreasing value",
+                result: Some(Value::test_list(vec![
+                    Value::test_int(2),
+                    Value::test_int(1),
+                    Value::test_int(0),
+                ])),
             },
             Example {
                 example: "[betty amy sarah] | sort",
-                description: "sort a list of strings",
-                result: Some(Value::list(
-                    vec![
-                        Value::test_string("amy"),
-                        Value::test_string("betty"),
-                        Value::test_string("sarah"),
-                    ],
-                    Span::test_data(),
-                )),
+                description: "Sort a list of strings",
+                result: Some(Value::test_list(vec![
+                    Value::test_string("amy"),
+                    Value::test_string("betty"),
+                    Value::test_string("sarah"),
+                ])),
             },
             Example {
                 example: "[betty amy sarah] | sort --reverse",
-                description: "sort a list of strings in reverse",
-                result: Some(Value::list(
-                    vec![
-                        Value::test_string("sarah"),
-                        Value::test_string("betty"),
-                        Value::test_string("amy"),
-                    ],
-                    Span::test_data(),
-                )),
+                description: "Sort a list of strings in reverse",
+                result: Some(Value::test_list(vec![
+                    Value::test_string("sarah"),
+                    Value::test_string("betty"),
+                    Value::test_string("amy"),
+                ])),
             },
             Example {
                 description: "Sort strings (case-insensitive)",
                 example: "[airplane Truck Car] | sort -i",
-                result: Some(Value::list(
-                    vec![
-                        Value::test_string("airplane"),
-                        Value::test_string("Car"),
-                        Value::test_string("Truck"),
-                    ],
-                    Span::test_data(),
-                )),
+                result: Some(Value::test_list(vec![
+                    Value::test_string("airplane"),
+                    Value::test_string("Car"),
+                    Value::test_string("Truck"),
+                ])),
             },
             Example {
                 description: "Sort strings (reversed case-insensitive)",
                 example: "[airplane Truck Car] | sort -i -r",
-                result: Some(Value::list(
-                    vec![
-                        Value::test_string("Truck"),
-                        Value::test_string("Car"),
-                        Value::test_string("airplane"),
-                    ],
-                    Span::test_data(),
-                )),
+                result: Some(Value::test_list(vec![
+                    Value::test_string("Truck"),
+                    Value::test_string("Car"),
+                    Value::test_string("airplane"),
+                ])),
+            },
+            Example {
+                description: "Sort alphanumeric strings in natural order",
+                example: "[foo1 foo10 foo9] | sort -n",
+                result: Some(Value::test_list(vec![
+                    Value::test_string("foo1"),
+                    Value::test_string("foo9"),
+                    Value::test_string("foo10"),
+                ])),
             },
             Example {
                 description: "Sort record by key (case-insensitive)",
@@ -134,233 +135,65 @@ impl Command for Sort {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
-        let head = call.head;
         let reverse = call.has_flag(engine_state, stack, "reverse")?;
         let insensitive = call.has_flag(engine_state, stack, "ignore-case")?;
         let natural = call.has_flag(engine_state, stack, "natural")?;
+        let sort_by_value = call.has_flag(engine_state, stack, "values")?;
         let metadata = input.metadata();
 
         let span = input.span().unwrap_or(call.head);
-        match input {
-            // Records have two sorting methods, toggled by presence or absence of -v
-            PipelineData::Value(Value::Record { val, .. }, ..) => {
-                let sort_by_value = call.has_flag(engine_state, stack, "values")?;
-                let record = sort_record(
+        let value = input.into_value(span)?;
+        let sorted: Value = match value {
+            Value::Record { val, .. } => {
+                // Records have two sorting methods, toggled by presence or absence of -v
+                let record = crate::sort_record(
                     val.into_owned(),
-                    span,
                     sort_by_value,
                     reverse,
                     insensitive,
                     natural,
-                );
-                Ok(record.into_pipeline_data())
+                )?;
+                Value::record(record, span)
             }
-            // Other values are sorted here
-            PipelineData::Value(v, ..)
-                if !matches!(v, Value::List { .. } | Value::Range { .. }) =>
-            {
-                Ok(v.into_pipeline_data())
-            }
-            pipe_data => {
-                let mut vec: Vec<_> = pipe_data.into_iter().collect();
-
-                sort(&mut vec, head, insensitive, natural)?;
+            value @ Value::List { .. } => {
+                // If we have a table specifically, then we want to sort along each column.
+                // Record's PartialOrd impl dictates that columns are compared in alphabetical order,
+                // so we have to explicitly compare by each column.
+                let r#type = value.get_type();
+                let mut vec = value.into_list().expect("matched list above");
+                if let Type::Table(cols) = r#type {
+                    let columns: Vec<Comparator> = cols
+                        .iter()
+                        .map(|col| vec![PathMember::string(col.0.clone(), false, Span::unknown())])
+                        .map(|members| CellPath { members })
+                        .map(Comparator::CellPath)
+                        .collect();
+                    crate::sort_by(&mut vec, columns, span, insensitive, natural)?;
+                } else {
+                    crate::sort(&mut vec, insensitive, natural)?;
+                }
 
                 if reverse {
                     vec.reverse()
                 }
 
-                let iter = vec.into_iter();
-                Ok(iter.into_pipeline_data_with_metadata(
-                    head,
-                    engine_state.signals().clone(),
-                    metadata,
-                ))
+                Value::list(vec, span)
             }
-        }
-    }
-}
-
-fn sort_record(
-    record: Record,
-    rec_span: Span,
-    sort_by_value: bool,
-    reverse: bool,
-    insensitive: bool,
-    natural: bool,
-) -> Value {
-    let mut input_pairs: Vec<(String, Value)> = record.into_iter().collect();
-    input_pairs.sort_by(|a, b| {
-        // Extract the data (if sort_by_value) or the column names for comparison
-        let left_res = if sort_by_value {
-            match &a.1 {
-                Value::String { val, .. } => val.clone(),
-                val => {
-                    if let Ok(val) = val.coerce_string() {
-                        val
-                    } else {
-                        // Values that can't be turned to strings are disregarded by the sort
-                        // (same as in sort_utils.rs)
-                        return Ordering::Equal;
-                    }
-                }
+            Value::Nothing { .. } => {
+                return Err(ShellError::PipelineEmpty {
+                    dst_span: value.span(),
+                })
             }
-        } else {
-            a.0.clone()
-        };
-        let right_res = if sort_by_value {
-            match &b.1 {
-                Value::String { val, .. } => val.clone(),
-                val => {
-                    if let Ok(val) = val.coerce_string() {
-                        val
-                    } else {
-                        // Values that can't be turned to strings are disregarded by the sort
-                        // (same as in sort_utils.rs)
-                        return Ordering::Equal;
-                    }
-                }
+            _ => {
+                return Err(ShellError::PipelineMismatch {
+                    exp_input_type: "record or list".to_string(),
+                    dst_span: call.head,
+                    src_span: value.span(),
+                })
             }
-        } else {
-            b.0.clone()
         };
-
-        // Fold case if case-insensitive
-        let left = if insensitive {
-            left_res.to_folded_case()
-        } else {
-            left_res
-        };
-        let right = if insensitive {
-            right_res.to_folded_case()
-        } else {
-            right_res
-        };
-
-        if natural {
-            compare_str(left, right)
-        } else {
-            left.cmp(&right)
-        }
-    });
-
-    if reverse {
-        input_pairs.reverse();
+        Ok(sorted.into_pipeline_data_with_metadata(metadata))
     }
-
-    Value::record(input_pairs.into_iter().collect(), rec_span)
-}
-
-pub fn sort(
-    vec: &mut [Value],
-    span: Span,
-    insensitive: bool,
-    natural: bool,
-) -> Result<(), ShellError> {
-    match vec.first() {
-        Some(Value::Record { val, .. }) => {
-            let columns: Vec<String> = val.columns().cloned().collect();
-            vec.sort_by(|a, b| process(a, b, &columns, span, insensitive, natural));
-        }
-        _ => {
-            vec.sort_by(|a, b| {
-                let span_a = a.span();
-                let span_b = b.span();
-                if insensitive {
-                    let folded_left = match a {
-                        Value::String { val, .. } => Value::string(val.to_folded_case(), span_a),
-                        _ => a.clone(),
-                    };
-
-                    let folded_right = match b {
-                        Value::String { val, .. } => Value::string(val.to_folded_case(), span_b),
-                        _ => b.clone(),
-                    };
-
-                    if natural {
-                        match (
-                            folded_left.coerce_into_string(),
-                            folded_right.coerce_into_string(),
-                        ) {
-                            (Ok(left), Ok(right)) => compare_str(left, right),
-                            _ => Ordering::Equal,
-                        }
-                    } else {
-                        folded_left
-                            .partial_cmp(&folded_right)
-                            .unwrap_or(Ordering::Equal)
-                    }
-                } else if natural {
-                    match (a.coerce_str(), b.coerce_str()) {
-                        (Ok(left), Ok(right)) => compare_str(left, right),
-                        _ => Ordering::Equal,
-                    }
-                } else {
-                    a.partial_cmp(b).unwrap_or(Ordering::Equal)
-                }
-            });
-        }
-    }
-    Ok(())
-}
-
-pub fn process(
-    left: &Value,
-    right: &Value,
-    columns: &[String],
-    span: Span,
-    insensitive: bool,
-    natural: bool,
-) -> Ordering {
-    for column in columns {
-        let left_value = left.get_data_by_key(column);
-
-        let left_res = match left_value {
-            Some(left_res) => left_res,
-            None => Value::nothing(span),
-        };
-
-        let right_value = right.get_data_by_key(column);
-
-        let right_res = match right_value {
-            Some(right_res) => right_res,
-            None => Value::nothing(span),
-        };
-
-        let result = if insensitive {
-            let span_left = left_res.span();
-            let span_right = right_res.span();
-            let folded_left = match left_res {
-                Value::String { val, .. } => Value::string(val.to_folded_case(), span_left),
-                _ => left_res,
-            };
-
-            let folded_right = match right_res {
-                Value::String { val, .. } => Value::string(val.to_folded_case(), span_right),
-                _ => right_res,
-            };
-            if natural {
-                match (
-                    folded_left.coerce_into_string(),
-                    folded_right.coerce_into_string(),
-                ) {
-                    (Ok(left), Ok(right)) => compare_str(left, right),
-                    _ => Ordering::Equal,
-                }
-            } else {
-                folded_left
-                    .partial_cmp(&folded_right)
-                    .unwrap_or(Ordering::Equal)
-            }
-        } else {
-            left_res.partial_cmp(&right_res).unwrap_or(Ordering::Equal)
-        };
-        if result != Ordering::Equal {
-            return result;
-        }
-    }
-
-    Ordering::Equal
 }
 
 #[cfg(test)]

crates/nu-command/src/filters/sort_by.rs

@@ -1,4 +1,6 @@
-use nu_engine::command_prelude::*;
+use nu_engine::{command_prelude::*, ClosureEval};
+
+use crate::Comparator;
 
 #[derive(Clone)]
 pub struct SortBy;
@@ -18,24 +20,37 @@ impl Command for SortBy {
                 (Type::record(), Type::table()),
                 (Type::table(), Type::table()),
             ])
-            .rest("columns", SyntaxShape::Any, "The column(s) to sort by.")
+            .rest(
+                "comparator",
+                SyntaxShape::OneOf(vec![
+                    SyntaxShape::CellPath,
+                    SyntaxShape::Closure(Some(vec![SyntaxShape::Any])), // key closure
+                    SyntaxShape::Closure(Some(vec![SyntaxShape::Any, SyntaxShape::Any])), // custom closure
+                ]),
+                "The cell path(s) or closure(s) to compare elements by.",
+            )
             .switch("reverse", "Sort in reverse order", Some('r'))
             .switch(
                 "ignore-case",
-                "Sort string-based columns case-insensitively",
+                "Sort string-based data case-insensitively",
                 Some('i'),
             )
             .switch(
                 "natural",
-                "Sort alphanumeric string-based columns naturally (1, 9, 10, 99, 100, ...)",
+                "Sort alphanumeric string-based data naturally (1, 9, 10, 99, 100, ...)",
                 Some('n'),
             )
+            .switch(
+                "custom",
+                "Use closures to specify a custom sort order, rather than to compute a comparison key",
+                Some('c'),
+            )
             .allow_variants_without_examples(true)
             .category(Category::Filters)
     }
 
     fn description(&self) -> &str {
-        "Sort by the given columns, in increasing order."
+        "Sort by the given cell path or closure."
     }
 
     fn examples(&self) -> Vec<Example> {
@@ -68,6 +83,41 @@ impl Command for SortBy {
                     }),
                 ])),
             },
+            Example {
+                description: "Sort by a nested value",
+                example: "[[name info]; [Cairo {founded: 969}] [Kyoto {founded: 794}]] | sort-by info.founded",
+                result: Some(Value::test_list(vec![
+                    Value::test_record(record! {
+                        "name" => Value::test_string("Kyoto"),
+                        "info" => Value::test_record(
+                            record! { "founded" => Value::test_int(794) },
+                        )}),
+                    Value::test_record(record! {
+                        "name" => Value::test_string("Cairo"),
+                        "info" => Value::test_record(
+                            record! { "founded" => Value::test_int(969) },
+                        )})
+                ])),
+            },
+            Example {
+                description: "Sort by the last value in a list",
+                example: "[[2 50] [10 1]] | sort-by { last }",
+                result: Some(Value::test_list(vec![
+                    Value::test_list(vec![Value::test_int(10), Value::test_int(1)]),
+                    Value::test_list(vec![Value::test_int(2), Value::test_int(50)])
+                ]))
+            },
+            Example {
+                description: "Sort in a custom order",
+                example: "[7 3 2 8 4] | sort-by -c {|a, b| $a < $b}",
+                result: Some(Value::test_list(vec![
+                    Value::test_int(2),
+                    Value::test_int(3),
+                    Value::test_int(4),
+                    Value::test_int(7),
+                    Value::test_int(8),
+                ]))
+            }
         ]
     }
 
@@ -79,39 +129,60 @@ impl Command for SortBy {
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
         let head = call.head;
-        let columns: Vec<String> = call.rest(engine_state, stack, 0)?;
+        let comparator_vals: Vec<Value> = call.rest(engine_state, stack, 0)?;
         let reverse = call.has_flag(engine_state, stack, "reverse")?;
         let insensitive = call.has_flag(engine_state, stack, "ignore-case")?;
         let natural = call.has_flag(engine_state, stack, "natural")?;
+        let custom = call.has_flag(engine_state, stack, "custom")?;
         let metadata = input.metadata();
         let mut vec: Vec<_> = input.into_iter_strict(head)?.collect();
 
-        if columns.is_empty() {
+        if comparator_vals.is_empty() {
             return Err(ShellError::MissingParameter {
-                param_name: "columns".into(),
+                param_name: "comparator".into(),
                 span: head,
             });
         }
 
-        crate::sort(&mut vec, columns, head, insensitive, natural)?;
+        let comparators = comparator_vals
+            .into_iter()
+            .map(|val| match val {
+                Value::CellPath { val, .. } => Ok(Comparator::CellPath(val)),
+                Value::Closure { val, .. } => {
+                    let closure_eval = ClosureEval::new(engine_state, stack, *val);
+                    if custom {
+                        Ok(Comparator::CustomClosure(closure_eval))
+                    } else {
+                        Ok(Comparator::KeyClosure(closure_eval))
+                    }
+                }
+                _ => Err(ShellError::TypeMismatch {
+                    err_message: "Cannot sort using a value which is not a cell path or closure"
+                        .into(),
+                    span: val.span(),
+                }),
+            })
+            .collect::<Result<_, _>>()?;
+
+        crate::sort_by(&mut vec, comparators, head, insensitive, natural)?;
 
         if reverse {
             vec.reverse()
         }
 
-        let iter = vec.into_iter();
-        Ok(iter.into_pipeline_data_with_metadata(head, engine_state.signals().clone(), metadata))
+        let val = Value::list(vec, head);
+        Ok(val.into_pipeline_data_with_metadata(metadata))
     }
 }
 
 #[cfg(test)]
 mod test {
+    use crate::{test_examples_with_commands, Last};
+
     use super::*;
 
     #[test]
     fn test_examples() {
-        use crate::test_examples;
-
-        test_examples(SortBy {})
+        test_examples_with_commands(SortBy {}, &[&Last]);
     }
 }

crates/nu-command/src/sort_utils.rs

@@ -1,351 +1,286 @@
-use alphanumeric_sort::compare_str;
-use nu_engine::column::nonexistent_column;
-use nu_protocol::{ShellError, Span, Value};
+use nu_engine::ClosureEval;
+use nu_protocol::{ast::CellPath, PipelineData, Record, ShellError, Span, Value};
 use nu_utils::IgnoreCaseExt;
 use std::cmp::Ordering;
 
-// This module includes sorting functionality that is useful in sort-by and elsewhere.
-// Eventually it would be nice to find a better home for it; sorting logic is only coupled
-// to commands for historical reasons.
+/// A specification of sort order for `sort_by`.
+///
+/// A closure comparator allows the user to return custom ordering to sort by.
+/// A cell path comparator uses the value referred to by the cell path as the sorting key.
+pub enum Comparator {
+    KeyClosure(ClosureEval),
+    CustomClosure(ClosureEval),
+    CellPath(CellPath),
+}
 
-/// Sort a value. This only makes sense for lists and list-like things,
-/// so for everything else we just return the value as-is.
-/// CustomValues are converted to their base value and then sorted.
-pub fn sort_value(
-    val: &Value,
-    sort_columns: Vec<String>,
-    ascending: bool,
-    insensitive: bool,
-    natural: bool,
-) -> Result<Value, ShellError> {
-    let span = val.span();
-    match val {
-        Value::List { vals, .. } => {
-            let mut vals = vals.clone();
-            sort(&mut vals, sort_columns, span, insensitive, natural)?;
+/// Sort a slice of `Value`s.
+///
+/// Sort has the following invariants, in order of precedence:
+/// - Null values (Nothing type) are always sorted to the end.
+/// - For natural sort, numeric values (numeric strings, ints, and floats) appear first, sorted by numeric value
+/// - Values appear by order of `Value`'s `PartialOrd`.
+/// - Sorting for values with equal ordering is stable.
+///
+/// Generally, values of different types are ordered by order of appearance in the `Value` enum.
+/// However, this is not always the case. For example, ints and floats will be grouped together since
+/// `Value`'s `PartialOrd` defines a non-decreasing ordering between non-decreasing integers and floats.
+pub fn sort(vec: &mut [Value], insensitive: bool, natural: bool) -> Result<(), ShellError> {
+    // allow the comparator function to indicate error
+    // by mutating this option captured by the closure,
+    // since sort_by closure must be infallible
+    let mut compare_err: Option<ShellError> = None;
 
-            if !ascending {
-                vals.reverse();
-            }
-
-            Ok(Value::list(vals, span))
+    vec.sort_by(|a, b| {
+        // we've already hit an error, bail out now
+        if compare_err.is_some() {
+            return Ordering::Equal;
         }
-        Value::Custom { val, .. } => {
-            let base_val = val.to_base_value(span)?;
-            sort_value(&base_val, sort_columns, ascending, insensitive, natural)
-        }
-        _ => Ok(val.to_owned()),
+
+        compare_values(a, b, insensitive, natural).unwrap_or_else(|err| {
+            compare_err.get_or_insert(err);
+            Ordering::Equal
+        })
+    });
+
+    if let Some(err) = compare_err {
+        Err(err)
+    } else {
+        Ok(())
     }
 }
 
-/// Sort a value in-place. This is more efficient than sort_value() because it
-/// avoids cloning, but it does not work for CustomValues; they are returned as-is.
-pub fn sort_value_in_place(
-    val: &mut Value,
-    sort_columns: Vec<String>,
-    ascending: bool,
-    insensitive: bool,
-    natural: bool,
-) -> Result<(), ShellError> {
-    let span = val.span();
-    if let Value::List { vals, .. } = val {
-        sort(vals, sort_columns, span, insensitive, natural)?;
-        if !ascending {
-            vals.reverse();
-        }
-    }
-    Ok(())
-}
-
-pub fn sort(
+/// Sort a slice of `Value`s by criteria specified by one or multiple `Comparator`s.
+pub fn sort_by(
     vec: &mut [Value],
-    sort_columns: Vec<String>,
-    span: Span,
+    mut comparators: Vec<Comparator>,
+    head_span: Span,
     insensitive: bool,
     natural: bool,
 ) -> Result<(), ShellError> {
-    let val_span = vec.first().map(|v| v.span()).unwrap_or(span);
-    match vec.first() {
-        Some(Value::Record { val: record, .. }) => {
-            if sort_columns.is_empty() {
-                // This uses the same format as the 'requires a column name' error in split_by.rs
-                return Err(ShellError::GenericError {
-                    error: "expected name".into(),
-                    msg: "requires a column name to sort table data".into(),
-                    span: Some(span),
-                    help: None,
-                    inner: vec![],
-                });
-            }
-
-            if let Some(nonexistent) = nonexistent_column(&sort_columns, record.columns()) {
-                return Err(ShellError::CantFindColumn {
-                    col_name: nonexistent,
-                    span: Some(span),
-                    src_span: val_span,
-                });
-            }
-
-            // check to make sure each value in each column in the record
-            // that we asked for is a string. So, first collect all the columns
-            // that we asked for into vals, then later make sure they're all
-            // strings.
-            let mut vals = vec![];
-            for item in vec.iter() {
-                for col in &sort_columns {
-                    let val = item
-                        .get_data_by_key(col)
-                        .unwrap_or_else(|| Value::nothing(Span::unknown()));
-                    vals.push(val);
-                }
-            }
-
-            let should_sort_case_insensitively = insensitive
-                && vals
-                    .iter()
-                    .all(|x| matches!(x.get_type(), nu_protocol::Type::String));
-
-            let should_sort_case_naturally = natural
-                && vals
-                    .iter()
-                    .all(|x| matches!(x.get_type(), nu_protocol::Type::String));
-
-            vec.sort_by(|a, b| {
-                compare(
-                    a,
-                    b,
-                    &sort_columns,
-                    span,
-                    should_sort_case_insensitively,
-                    should_sort_case_naturally,
-                )
-            });
-        }
-        _ => {
-            vec.sort_by(|a, b| {
-                if insensitive {
-                    let span_a = a.span();
-                    let span_b = b.span();
-                    let folded_left = match a {
-                        Value::String { val, .. } => Value::string(val.to_folded_case(), span_a),
-                        _ => a.clone(),
-                    };
-
-                    let folded_right = match b {
-                        Value::String { val, .. } => Value::string(val.to_folded_case(), span_b),
-                        _ => b.clone(),
-                    };
-
-                    if natural {
-                        match (
-                            folded_left.coerce_into_string(),
-                            folded_right.coerce_into_string(),
-                        ) {
-                            (Ok(left), Ok(right)) => compare_str(left, right),
-                            _ => Ordering::Equal,
-                        }
-                    } else {
-                        folded_left
-                            .partial_cmp(&folded_right)
-                            .unwrap_or(Ordering::Equal)
-                    }
-                } else if natural {
-                    match (a.coerce_str(), b.coerce_str()) {
-                        (Ok(left), Ok(right)) => compare_str(left, right),
-                        _ => Ordering::Equal,
-                    }
-                } else {
-                    a.partial_cmp(b).unwrap_or(Ordering::Equal)
-                }
-            });
-        }
+    if comparators.is_empty() {
+        // This uses the same format as the 'requires a column name' error in split_by.rs
+        return Err(ShellError::GenericError {
+            error: "expected name".into(),
+            msg: "requires a cell path or closure to sort data".into(),
+            span: Some(head_span),
+            help: None,
+            inner: vec![],
+        });
+    }
+
+    // allow the comparator function to indicate error
+    // by mutating this option captured by the closure,
+    // since sort_by closure must be infallible
+    let mut compare_err: Option<ShellError> = None;
+
+    vec.sort_by(|a, b| {
+        compare_by(
+            a,
+            b,
+            &mut comparators,
+            head_span,
+            insensitive,
+            natural,
+            &mut compare_err,
+        )
+    });
+
+    if let Some(err) = compare_err {
+        Err(err)
+    } else {
+        Ok(())
     }
-    Ok(())
 }
 
-pub fn compare(
+/// Sort a record's key-value pairs.
+///
+/// Can sort by key or by value.
+pub fn sort_record(
+    record: Record,
+    sort_by_value: bool,
+    reverse: bool,
+    insensitive: bool,
+    natural: bool,
+) -> Result<Record, ShellError> {
+    let mut input_pairs: Vec<(String, Value)> = record.into_iter().collect();
+
+    // allow the comparator function to indicate error
+    // by mutating this option captured by the closure,
+    // since sort_by closure must be infallible
+    let mut compare_err: Option<ShellError> = None;
+
+    if sort_by_value {
+        input_pairs.sort_by(|a, b| {
+            // we've already hit an error, bail out now
+            if compare_err.is_some() {
+                return Ordering::Equal;
+            }
+
+            compare_values(&a.1, &b.1, insensitive, natural).unwrap_or_else(|err| {
+                compare_err.get_or_insert(err);
+                Ordering::Equal
+            })
+        });
+    } else {
+        input_pairs.sort_by(|a, b| compare_strings(&a.0, &b.0, insensitive, natural));
+    };
+
+    if let Some(err) = compare_err {
+        return Err(err);
+    }
+
+    if reverse {
+        input_pairs.reverse()
+    }
+
+    Ok(input_pairs.into_iter().collect())
+}
+
+pub fn compare_by(
     left: &Value,
     right: &Value,
-    columns: &[String],
+    comparators: &mut [Comparator],
     span: Span,
     insensitive: bool,
     natural: bool,
+    error: &mut Option<ShellError>,
 ) -> Ordering {
-    for column in columns {
-        let left_value = left.get_data_by_key(column);
-
-        let left_res = match left_value {
-            Some(left_res) => left_res,
-            None => Value::nothing(span),
-        };
-
-        let right_value = right.get_data_by_key(column);
-
-        let right_res = match right_value {
-            Some(right_res) => right_res,
-            None => Value::nothing(span),
-        };
-
-        let result = if insensitive {
-            let span_left = left_res.span();
-            let span_right = right_res.span();
-            let folded_left = match left_res {
-                Value::String { val, .. } => Value::string(val.to_folded_case(), span_left),
-                _ => left_res,
-            };
-
-            let folded_right = match right_res {
-                Value::String { val, .. } => Value::string(val.to_folded_case(), span_right),
-                _ => right_res,
-            };
-            if natural {
-                match (
-                    folded_left.coerce_into_string(),
-                    folded_right.coerce_into_string(),
-                ) {
-                    (Ok(left), Ok(right)) => compare_str(left, right),
-                    _ => Ordering::Equal,
-                }
-            } else {
-                folded_left
-                    .partial_cmp(&folded_right)
-                    .unwrap_or(Ordering::Equal)
+    // we've already hit an error, bail out now
+    if error.is_some() {
+        return Ordering::Equal;
+    }
+    for cmp in comparators.iter_mut() {
+        let result = match cmp {
+            Comparator::CellPath(cell_path) => {
+                compare_cell_path(left, right, cell_path, insensitive, natural)
             }
-        } else if natural {
-            match (
-                left_res.coerce_into_string(),
-                right_res.coerce_into_string(),
-            ) {
-                (Ok(left), Ok(right)) => compare_str(left, right),
-                _ => Ordering::Equal,
+            Comparator::KeyClosure(closure) => {
+                compare_key_closure(left, right, closure, span, insensitive, natural)
+            }
+            Comparator::CustomClosure(closure) => {
+                compare_custom_closure(left, right, closure, span)
             }
-        } else {
-            left_res.partial_cmp(&right_res).unwrap_or(Ordering::Equal)
         };
-        if result != Ordering::Equal {
-            return result;
+        match result {
+            Ok(Ordering::Equal) => {}
+            Ok(ordering) => return ordering,
+            Err(err) => {
+                // don't bother continuing through the remaining comparators as we've hit an error
+                // don't overwrite if there's an existing error
+                error.get_or_insert(err);
+                return Ordering::Equal;
+            }
         }
     }
-
     Ordering::Equal
 }
 
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use nu_protocol::{record, Value};
+/// Determines whether a value should be sorted as a string
+///
+/// If we're natural sorting, we want to sort strings, integers, and floats alphanumerically, so we should string sort.
+/// Otherwise, we only want to string sort if both values are strings or globs (to enable case insensitive comparison)
+fn should_sort_as_string(val: &Value, natural: bool) -> bool {
+    matches!(
+        (val, natural),
+        (&Value::String { .. }, _)
+            | (&Value::Glob { .. }, _)
+            | (&Value::Int { .. }, true)
+            | (&Value::Float { .. }, true)
+    )
+}
 
-    #[test]
-    fn test_sort_value() {
-        let val = Value::test_list(vec![
-            Value::test_record(record! {
-            "fruit" => Value::test_string("pear"),
-            "count" => Value::test_int(3),
-            }),
-            Value::test_record(record! {
-            "fruit" => Value::test_string("orange"),
-            "count" => Value::test_int(7),
-            }),
-            Value::test_record(record! {
-            "fruit" => Value::test_string("apple"),
-            "count" => Value::test_int(9),
-            }),
-        ]);
+/// Simple wrapper around `should_sort_as_string` to determine if two values
+/// should be compared as strings.
+fn should_string_compare(left: &Value, right: &Value, natural: bool) -> bool {
+    should_sort_as_string(left, natural) && should_sort_as_string(right, natural)
+}
 
-        let sorted_alphabetically =
-            sort_value(&val, vec!["fruit".to_string()], true, false, false).unwrap();
-        assert_eq!(
-            sorted_alphabetically,
-            Value::test_list(vec![
-                Value::test_record(record! {
-                "fruit" => Value::test_string("apple"),
-                "count" => Value::test_int(9),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("orange"),
-                "count" => Value::test_int(7),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("pear"),
-                "count" => Value::test_int(3),
-                            }),
-            ],)
-        );
-
-        let sorted_by_count_desc =
-            sort_value(&val, vec!["count".to_string()], false, false, false).unwrap();
-        assert_eq!(
-            sorted_by_count_desc,
-            Value::test_list(vec![
-                Value::test_record(record! {
-                "fruit" => Value::test_string("apple"),
-                "count" => Value::test_int(9),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("orange"),
-                "count" => Value::test_int(7),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("pear"),
-                "count" => Value::test_int(3),
-                            }),
-            ],)
-        );
-    }
-
-    #[test]
-    fn test_sort_value_in_place() {
-        let mut val = Value::test_list(vec![
-            Value::test_record(record! {
-            "fruit" => Value::test_string("pear"),
-            "count" => Value::test_int(3),
-            }),
-            Value::test_record(record! {
-            "fruit" => Value::test_string("orange"),
-            "count" => Value::test_int(7),
-            }),
-            Value::test_record(record! {
-            "fruit" => Value::test_string("apple"),
-            "count" => Value::test_int(9),
-            }),
-        ]);
-
-        sort_value_in_place(&mut val, vec!["fruit".to_string()], true, false, false).unwrap();
-        assert_eq!(
-            val,
-            Value::test_list(vec![
-                Value::test_record(record! {
-                "fruit" => Value::test_string("apple"),
-                "count" => Value::test_int(9),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("orange"),
-                "count" => Value::test_int(7),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("pear"),
-                "count" => Value::test_int(3),
-                            }),
-            ],)
-        );
-
-        sort_value_in_place(&mut val, vec!["count".to_string()], false, false, false).unwrap();
-        assert_eq!(
-            val,
-            Value::test_list(vec![
-                Value::test_record(record! {
-                "fruit" => Value::test_string("apple"),
-                "count" => Value::test_int(9),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("orange"),
-                "count" => Value::test_int(7),
-                            }),
-                Value::test_record(record! {
-                "fruit" => Value::test_string("pear"),
-                "count" => Value::test_int(3),
-                            }),
-            ],)
-        );
+pub fn compare_values(
+    left: &Value,
+    right: &Value,
+    insensitive: bool,
+    natural: bool,
+) -> Result<Ordering, ShellError> {
+    if should_string_compare(left, right, natural) {
+        Ok(compare_strings(
+            &left.coerce_str()?,
+            &right.coerce_str()?,
+            insensitive,
+            natural,
+        ))
+    } else {
+        Ok(left.partial_cmp(right).unwrap_or(Ordering::Equal))
     }
 }
+
+pub fn compare_strings(left: &str, right: &str, insensitive: bool, natural: bool) -> Ordering {
+    fn compare_inner<T>(left: T, right: T, natural: bool) -> Ordering
+    where
+        T: AsRef<str> + Ord,
+    {
+        if natural {
+            alphanumeric_sort::compare_str(left, right)
+        } else {
+            left.cmp(&right)
+        }
+    }
+
+    // only allocate a String if necessary for case folding
+    if insensitive {
+        compare_inner(left.to_folded_case(), right.to_folded_case(), natural)
+    } else {
+        compare_inner(left, right, natural)
+    }
+}
+
+pub fn compare_cell_path(
+    left: &Value,
+    right: &Value,
+    cell_path: &CellPath,
+    insensitive: bool,
+    natural: bool,
+) -> Result<Ordering, ShellError> {
+    let left = left.clone().follow_cell_path(&cell_path.members, false)?;
+    let right = right.clone().follow_cell_path(&cell_path.members, false)?;
+    compare_values(&left, &right, insensitive, natural)
+}
+
+pub fn compare_key_closure(
+    left: &Value,
+    right: &Value,
+    closure_eval: &mut ClosureEval,
+    span: Span,
+    insensitive: bool,
+    natural: bool,
+) -> Result<Ordering, ShellError> {
+    let left_key = closure_eval
+        .run_with_value(left.clone())?
+        .into_value(span)?;
+    let right_key = closure_eval
+        .run_with_value(right.clone())?
+        .into_value(span)?;
+    compare_values(&left_key, &right_key, insensitive, natural)
+}
+
+pub fn compare_custom_closure(
+    left: &Value,
+    right: &Value,
+    closure_eval: &mut ClosureEval,
+    span: Span,
+) -> Result<Ordering, ShellError> {
+    closure_eval
+        .add_arg(left.clone())
+        .add_arg(right.clone())
+        .run_with_input(PipelineData::Value(
+            Value::list(vec![left.clone(), right.clone()], span),
+            None,
+        ))
+        .and_then(|data| data.into_value(span))
+        .map(|val| {
+            if val.is_true() {
+                Ordering::Less
+            } else {
+                Ordering::Greater
+            }
+        })
+}

crates/nu-command/tests/commands/sort.rs

@@ -33,6 +33,20 @@ fn sort_primitive_values() {
     assert_eq!(actual.out, "authors = [\"The Nushell Project Developers\"]");
 }
 
+#[test]
+fn sort_table() {
+    // if a table's records are compared directly rather than holistically as a table,
+    // [100, 10, 5] will come before [100, 5, 8] because record comparison
+    // compares columns by alphabetical order, so price will be checked before quantity
+    let actual =
+        nu!("[[id, quantity, price]; [100, 10, 5], [100, 5, 8], [100, 5, 1]] | sort | to nuon");
+
+    assert_eq!(
+        actual.out,
+        r#"[[id, quantity, price]; [100, 5, 1], [100, 5, 8], [100, 10, 5]]"#
+    );
+}
+
 #[test]
 fn sort_different_types() {
     let actual = nu!("[a, 1, b, 2, c, 3, [4, 5, 6], d, 4, [1, 2, 3]] | sort | to json --raw");

crates/nu-command/tests/main.rs

@@ -6,6 +6,7 @@ use quickcheck_macros::quickcheck;
 
 mod commands;
 mod format_conversions;
+mod sort_utils;
 
 fn create_default_context() -> EngineState {
     nu_command::add_shell_command_context(nu_cmd_lang::create_default_context())

crates/nu-command/tests/sort_utils.rs

@@ -0,0 +1,554 @@
+use nu_command::{sort, sort_by, sort_record, Comparator};
+use nu_protocol::{
+    ast::{CellPath, PathMember},
+    record, Record, Span, Value,
+};
+
+#[test]
+fn test_sort_basic() {
+    let mut list = vec![
+        Value::test_string("foo"),
+        Value::test_int(2),
+        Value::test_int(3),
+        Value::test_string("bar"),
+        Value::test_int(1),
+        Value::test_string("baz"),
+    ];
+
+    assert!(sort(&mut list, false, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(1),
+            Value::test_int(2),
+            Value::test_int(3),
+            Value::test_string("bar"),
+            Value::test_string("baz"),
+            Value::test_string("foo")
+        ]
+    );
+}
+
+#[test]
+fn test_sort_nothing() {
+    // Nothing values should always be sorted to the end of any list
+    let mut list = vec![
+        Value::test_int(1),
+        Value::test_nothing(),
+        Value::test_int(2),
+        Value::test_string("foo"),
+        Value::test_nothing(),
+        Value::test_string("bar"),
+    ];
+
+    assert!(sort(&mut list, false, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(1),
+            Value::test_int(2),
+            Value::test_string("bar"),
+            Value::test_string("foo"),
+            Value::test_nothing(),
+            Value::test_nothing()
+        ]
+    );
+
+    // Ensure that nothing values are sorted after *all* types,
+    // even types which may follow `Nothing` in the PartialOrd order
+
+    // unstable_name_collision
+    // can be switched to std intersperse when stabilized
+    let mut values: Vec<Value> =
+        itertools::intersperse(Value::test_values(), Value::test_nothing()).collect();
+
+    let nulls = values
+        .iter()
+        .filter(|item| item == &&Value::test_nothing())
+        .count();
+
+    assert!(sort(&mut values, false, false).is_ok());
+
+    // check if the last `nulls` values of the sorted list are indeed null
+    assert_eq!(&values[(nulls - 1)..], vec![Value::test_nothing(); nulls])
+}
+
+#[test]
+fn test_sort_natural_basic() {
+    let mut list = vec![
+        Value::test_string("foo99"),
+        Value::test_string("foo9"),
+        Value::test_string("foo1"),
+        Value::test_string("foo100"),
+        Value::test_string("foo10"),
+        Value::test_string("1"),
+        Value::test_string("10"),
+        Value::test_string("100"),
+        Value::test_string("9"),
+        Value::test_string("99"),
+    ];
+
+    assert!(sort(&mut list, false, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_string("1"),
+            Value::test_string("10"),
+            Value::test_string("100"),
+            Value::test_string("9"),
+            Value::test_string("99"),
+            Value::test_string("foo1"),
+            Value::test_string("foo10"),
+            Value::test_string("foo100"),
+            Value::test_string("foo9"),
+            Value::test_string("foo99"),
+        ]
+    );
+
+    assert!(sort(&mut list, false, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_string("1"),
+            Value::test_string("9"),
+            Value::test_string("10"),
+            Value::test_string("99"),
+            Value::test_string("100"),
+            Value::test_string("foo1"),
+            Value::test_string("foo9"),
+            Value::test_string("foo10"),
+            Value::test_string("foo99"),
+            Value::test_string("foo100"),
+        ]
+    );
+}
+
+#[test]
+fn test_sort_natural_mixed_types() {
+    let mut list = vec![
+        Value::test_string("1"),
+        Value::test_int(99),
+        Value::test_int(1),
+        Value::test_float(1000.0),
+        Value::test_int(9),
+        Value::test_string("9"),
+        Value::test_int(100),
+        Value::test_string("99"),
+        Value::test_float(2.0),
+        Value::test_string("100"),
+        Value::test_int(10),
+        Value::test_string("10"),
+    ];
+
+    assert!(sort(&mut list, false, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(1),
+            Value::test_float(2.0),
+            Value::test_int(9),
+            Value::test_int(10),
+            Value::test_int(99),
+            Value::test_int(100),
+            Value::test_float(1000.0),
+            Value::test_string("1"),
+            Value::test_string("10"),
+            Value::test_string("100"),
+            Value::test_string("9"),
+            Value::test_string("99")
+        ]
+    );
+
+    assert!(sort(&mut list, false, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(1),
+            Value::test_string("1"),
+            Value::test_float(2.0),
+            Value::test_int(9),
+            Value::test_string("9"),
+            Value::test_int(10),
+            Value::test_string("10"),
+            Value::test_int(99),
+            Value::test_string("99"),
+            Value::test_int(100),
+            Value::test_string("100"),
+            Value::test_float(1000.0),
+        ]
+    );
+}
+
+#[test]
+fn test_sort_natural_no_numeric_values() {
+    // If list contains no numeric strings, it should be sorted the
+    // same with or without natural sorting
+    let mut normal = vec![
+        Value::test_string("golf"),
+        Value::test_bool(false),
+        Value::test_string("alfa"),
+        Value::test_string("echo"),
+        Value::test_int(7),
+        Value::test_int(10),
+        Value::test_bool(true),
+        Value::test_string("uniform"),
+        Value::test_int(3),
+        Value::test_string("tango"),
+    ];
+    let mut natural = normal.clone();
+
+    assert!(sort(&mut normal, false, false).is_ok());
+    assert!(sort(&mut natural, false, true).is_ok());
+    assert_eq!(normal, natural);
+}
+
+#[test]
+fn test_sort_natural_type_order() {
+    // This test is to prevent regression to a previous natural sort behavior
+    // where values of different types would be intermixed.
+    // Only numeric values (ints, floats, and numeric strings) should be intermixed
+    //
+    // This list would previously be incorrectly sorted like this:
+    // ╭────┬─────────╮
+    // │  0 │       1 │
+    // │  1 │ golf    │
+    // │  2 │ false   │
+    // │  3 │       7 │
+    // │  4 │      10 │
+    // │  5 │ alfa    │
+    // │  6 │ true    │
+    // │  7 │ uniform │
+    // │  8 │ true    │
+    // │  9 │       3 │
+    // │ 10 │ false   │
+    // │ 11 │ tango   │
+    // ╰────┴─────────╯
+
+    let mut list = vec![
+        Value::test_string("golf"),
+        Value::test_int(1),
+        Value::test_bool(false),
+        Value::test_string("alfa"),
+        Value::test_int(7),
+        Value::test_int(10),
+        Value::test_bool(true),
+        Value::test_string("uniform"),
+        Value::test_bool(true),
+        Value::test_int(3),
+        Value::test_bool(false),
+        Value::test_string("tango"),
+    ];
+
+    assert!(sort(&mut list, false, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_bool(false),
+            Value::test_bool(false),
+            Value::test_bool(true),
+            Value::test_bool(true),
+            Value::test_int(1),
+            Value::test_int(3),
+            Value::test_int(7),
+            Value::test_int(10),
+            Value::test_string("alfa"),
+            Value::test_string("golf"),
+            Value::test_string("tango"),
+            Value::test_string("uniform")
+        ]
+    );
+
+    // Only ints, floats, and numeric strings should be intermixed
+    // While binary primitives and datetimes can be coerced into strings, it doesn't make sense to sort them with numbers
+    // Binary primitives can hold multiple values, not just one, so shouldn't be compared to single values
+    // Datetimes don't have a single obvious numeric representation, and if we chose one it would be ambiguous to the user
+
+    let year_three = chrono::NaiveDate::from_ymd_opt(3, 1, 1)
+        .unwrap()
+        .and_hms_opt(0, 0, 0)
+        .unwrap()
+        .and_utc();
+
+    let mut list = vec![
+        Value::test_int(10),
+        Value::test_float(6.0),
+        Value::test_int(1),
+        Value::test_binary([3]),
+        Value::test_string("2"),
+        Value::test_date(year_three.into()),
+        Value::test_int(4),
+        Value::test_binary([52]),
+        Value::test_float(9.0),
+        Value::test_string("5"),
+        Value::test_date(chrono::DateTime::UNIX_EPOCH.into()),
+        Value::test_int(7),
+        Value::test_string("8"),
+        Value::test_float(3.0),
+        Value::test_string("foobar"),
+    ];
+    assert!(sort(&mut list, false, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(1),
+            Value::test_string("2"),
+            Value::test_float(3.0),
+            Value::test_int(4),
+            Value::test_string("5"),
+            Value::test_float(6.0),
+            Value::test_int(7),
+            Value::test_string("8"),
+            Value::test_float(9.0),
+            Value::test_int(10),
+            Value::test_string("foobar"),
+            // the ordering of date and binary here may change if the PartialOrd order is changed,
+            // but they should not be intermixed with the above
+            Value::test_date(year_three.into()),
+            Value::test_date(chrono::DateTime::UNIX_EPOCH.into()),
+            Value::test_binary([3]),
+            Value::test_binary([52]),
+        ]
+    );
+}
+
+#[test]
+fn test_sort_insensitive() {
+    // Test permutations between insensitive and natural
+    // Ensure that strings with equal insensitive orderings
+    // are sorted stably. (FOO then foo, bar then BAR)
+    let source = vec![
+        Value::test_string("FOO"),
+        Value::test_string("foo"),
+        Value::test_int(100),
+        Value::test_string("9"),
+        Value::test_string("bar"),
+        Value::test_int(10),
+        Value::test_string("baz"),
+        Value::test_string("BAR"),
+    ];
+    let mut list;
+
+    // sensitive + non-natural
+    list = source.clone();
+    assert!(sort(&mut list, false, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(10),
+            Value::test_int(100),
+            Value::test_string("9"),
+            Value::test_string("BAR"),
+            Value::test_string("FOO"),
+            Value::test_string("bar"),
+            Value::test_string("baz"),
+            Value::test_string("foo"),
+        ]
+    );
+
+    // sensitive + natural
+    list = source.clone();
+    assert!(sort(&mut list, false, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_string("9"),
+            Value::test_int(10),
+            Value::test_int(100),
+            Value::test_string("BAR"),
+            Value::test_string("FOO"),
+            Value::test_string("bar"),
+            Value::test_string("baz"),
+            Value::test_string("foo"),
+        ]
+    );
+
+    // insensitive + non-natural
+    list = source.clone();
+    assert!(sort(&mut list, true, false).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_int(10),
+            Value::test_int(100),
+            Value::test_string("9"),
+            Value::test_string("bar"),
+            Value::test_string("BAR"),
+            Value::test_string("baz"),
+            Value::test_string("FOO"),
+            Value::test_string("foo"),
+        ]
+    );
+
+    // insensitive + natural
+    list = source.clone();
+    assert!(sort(&mut list, true, true).is_ok());
+    assert_eq!(
+        list,
+        vec![
+            Value::test_string("9"),
+            Value::test_int(10),
+            Value::test_int(100),
+            Value::test_string("bar"),
+            Value::test_string("BAR"),
+            Value::test_string("baz"),
+            Value::test_string("FOO"),
+            Value::test_string("foo"),
+        ]
+    );
+}
+
+// Helper function to assert that two records are equal
+// with their key-value pairs in the same order
+fn assert_record_eq(a: Record, b: Record) {
+    assert_eq!(
+        a.into_iter().collect::<Vec<_>>(),
+        b.into_iter().collect::<Vec<_>>(),
+    )
+}
+
+#[test]
+fn test_sort_record_keys() {
+    // Basic record sort test
+    let record = record! {
+        "golf" => Value::test_string("bar"),
+        "alfa" => Value::test_string("foo"),
+        "echo" => Value::test_int(123),
+    };
+
+    let sorted = sort_record(record, false, false, false, false).unwrap();
+    assert_record_eq(
+        sorted,
+        record! {
+            "alfa" => Value::test_string("foo"),
+            "echo" => Value::test_int(123),
+            "golf" => Value::test_string("bar"),
+        },
+    );
+}
+
+#[test]
+fn test_sort_record_values() {
+    // This test is to prevent a regression where integers and strings would be
+    // intermixed non-naturally when sorting a record by value without the natural flag:
+    //
+    // This record would previously be incorrectly sorted like this:
+    // ╭─────────┬─────╮
+    // │ alfa    │ 1   │
+    // │ charlie │ 1   │
+    // │ india   │ 10  │
+    // │ juliett │ 10  │
+    // │ foxtrot │ 100 │
+    // │ hotel   │ 100 │
+    // │ delta   │ 9   │
+    // │ echo    │ 9   │
+    // │ bravo   │ 99  │
+    // │ golf    │ 99  │
+    // ╰─────────┴─────╯
+
+    let record = record! {
+        "alfa" => Value::test_string("1"),
+        "bravo" => Value::test_int(99),
+        "charlie" => Value::test_int(1),
+        "delta" => Value::test_int(9),
+        "echo" => Value::test_string("9"),
+        "foxtrot" => Value::test_int(100),
+        "golf" => Value::test_string("99"),
+        "hotel" => Value::test_string("100"),
+        "india" => Value::test_int(10),
+        "juliett" => Value::test_string("10"),
+    };
+
+    // non-natural sort
+    let sorted = sort_record(record.clone(), true, false, false, false).unwrap();
+    assert_record_eq(
+        sorted,
+        record! {
+            "charlie" => Value::test_int(1),
+            "delta" => Value::test_int(9),
+            "india" => Value::test_int(10),
+            "bravo" => Value::test_int(99),
+            "foxtrot" => Value::test_int(100),
+            "alfa" => Value::test_string("1"),
+            "juliett" => Value::test_string("10"),
+            "hotel" => Value::test_string("100"),
+            "echo" => Value::test_string("9"),
+            "golf" => Value::test_string("99"),
+        },
+    );
+
+    // natural sort
+    let sorted = sort_record(record.clone(), true, false, false, true).unwrap();
+    assert_record_eq(
+        sorted,
+        record! {
+            "alfa" => Value::test_string("1"),
+            "charlie" => Value::test_int(1),
+            "delta" => Value::test_int(9),
+            "echo" => Value::test_string("9"),
+            "india" => Value::test_int(10),
+            "juliett" => Value::test_string("10"),
+            "bravo" => Value::test_int(99),
+            "golf" => Value::test_string("99"),
+            "foxtrot" => Value::test_int(100),
+            "hotel" => Value::test_string("100"),
+        },
+    );
+}
+
+#[test]
+fn test_sort_equivalent() {
+    // Ensure that sort, sort_by, and record sort have equivalent sorting logic
+    let phonetic = vec![
+        "alfa", "bravo", "charlie", "delta", "echo", "foxtrot", "golf", "hotel", "india",
+        "juliett", "kilo", "lima", "mike", "november", "oscar", "papa", "quebec", "romeo",
+        "sierra", "tango", "uniform", "victor", "whiskey", "xray", "yankee", "zulu",
+    ];
+
+    // filter out errors, since we can't sort_by on those
+    let mut values: Vec<Value> = Value::test_values()
+        .into_iter()
+        .filter(|val| !matches!(val, Value::Error { .. }))
+        .collect();
+
+    // reverse sort test values
+    values.sort_by(|a, b| b.partial_cmp(a).unwrap());
+
+    let mut list = values.clone();
+    let mut table: Vec<Value> = values
+        .clone()
+        .into_iter()
+        .map(|val| Value::test_record(record! { "value" => val }))
+        .collect();
+    let record = Record::from_iter(phonetic.into_iter().map(str::to_string).zip(values));
+
+    let comparator = Comparator::CellPath(CellPath {
+        members: vec![PathMember::String {
+            val: "value".to_string(),
+            span: Span::test_data(),
+            optional: false,
+        }],
+    });
+
+    assert!(sort(&mut list, false, false).is_ok());
+    assert!(sort_by(
+        &mut table,
+        vec![comparator],
+        Span::test_data(),
+        false,
+        false
+    )
+    .is_ok());
+
+    let record_sorted = sort_record(record.clone(), true, false, false, false).unwrap();
+    let record_vals: Vec<Value> = record_sorted.into_iter().map(|pair| pair.1).collect();
+
+    let table_vals: Vec<Value> = table
+        .clone()
+        .into_iter()
+        .map(|record| record.into_record().unwrap().remove("value").unwrap())
+        .collect();
+
+    assert_eq!(list, record_vals);
+    assert_eq!(record_vals, table_vals);
+    // list == table_vals by transitive property
+}

crates/nu-protocol/src/value/mod.rs

@@ -68,6 +68,21 @@ pub enum Value {
         #[serde(rename = "span")]
         internal_span: Span,
     },
+    String {
+        val: String,
+        // note: spans are being refactored out of Value
+        // please use .span() instead of matching this span value
+        #[serde(rename = "span")]
+        internal_span: Span,
+    },
+    Glob {
+        val: String,
+        no_expand: bool,
+        // note: spans are being refactored out of Value
+        // please use .span() instead of matching this span value
+        #[serde(rename = "span")]
+        internal_span: Span,
+    },
     Filesize {
         val: i64,
         // note: spans are being refactored out of Value
@@ -96,21 +111,6 @@ pub enum Value {
         #[serde(rename = "span")]
         internal_span: Span,
     },
-    String {
-        val: String,
-        // note: spans are being refactored out of Value
-        // please use .span() instead of matching this span value
-        #[serde(rename = "span")]
-        internal_span: Span,
-    },
-    Glob {
-        val: String,
-        no_expand: bool,
-        // note: spans are being refactored out of Value
-        // please use .span() instead of matching this span value
-        #[serde(rename = "span")]
-        internal_span: Span,
-    },
     Record {
         val: SharedCow<Record>,
         // note: spans are being refactored out of Value
@@ -132,12 +132,6 @@ pub enum Value {
         #[serde(rename = "span")]
         internal_span: Span,
     },
-    Nothing {
-        // note: spans are being refactored out of Value
-        // please use .span() instead of matching this span value
-        #[serde(rename = "span")]
-        internal_span: Span,
-    },
     Error {
         error: Box<ShellError>,
         // note: spans are being refactored out of Value
@@ -166,6 +160,12 @@ pub enum Value {
         #[serde(rename = "span")]
         internal_span: Span,
     },
+    Nothing {
+        // note: spans are being refactored out of Value
+        // please use .span() instead of matching this span value
+        #[serde(rename = "span")]
+        internal_span: Span,
+    },
 }
 
 impl Clone for Value {
@@ -370,6 +370,7 @@ impl Value {
     /// - `Int`
     /// - `Float`
     /// - `String`
+    /// - `Glob`
     /// - `Binary` (only if valid utf-8)
     /// - `Date`
     ///
@@ -382,6 +383,7 @@ impl Value {
     ///             Value::Int { .. }
     ///                 | Value::Float { .. }
     ///                 | Value::String { .. }
+    ///                 | Value::Glob { .. }
     ///                 | Value::Binary { .. }
     ///                 | Value::Date { .. }
     ///         ),
@@ -394,6 +396,7 @@ impl Value {
             Value::Int { val, .. } => Ok(Cow::Owned(val.to_string())),
             Value::Float { val, .. } => Ok(Cow::Owned(val.to_string())),
             Value::String { val, .. } => Ok(Cow::Borrowed(val)),
+            Value::Glob { val, .. } => Ok(Cow::Borrowed(val)),
             Value::Binary { val, .. } => match std::str::from_utf8(val) {
                 Ok(s) => Ok(Cow::Borrowed(s)),
                 Err(_) => self.cant_convert_to("string"),
@@ -420,6 +423,7 @@ impl Value {
     /// - `Int`
     /// - `Float`
     /// - `String`
+    /// - `Glob`
     /// - `Binary` (only if valid utf-8)
     /// - `Date`
     ///
@@ -432,6 +436,7 @@ impl Value {
     ///             Value::Int { .. }
     ///                 | Value::Float { .. }
     ///                 | Value::String { .. }
+    ///                 | Value::Glob { .. }
     ///                 | Value::Binary { .. }
     ///                 | Value::Date { .. }
     ///         ),
@@ -449,6 +454,7 @@ impl Value {
     /// - `Int`
     /// - `Float`
     /// - `String`
+    /// - `Glob`
     /// - `Binary` (only if valid utf-8)
     /// - `Date`
     ///
@@ -461,6 +467,7 @@ impl Value {
     ///             Value::Int { .. }
     ///                 | Value::Float { .. }
     ///                 | Value::String { .. }
+    ///                 | Value::Glob { .. }
     ///                 | Value::Binary { .. }
     ///                 | Value::Date { .. }
     ///         ),
@@ -474,6 +481,7 @@ impl Value {
             Value::Int { val, .. } => Ok(val.to_string()),
             Value::Float { val, .. } => Ok(val.to_string()),
             Value::String { val, .. } => Ok(val),
+            Value::Glob { val, .. } => Ok(val),
             Value::Binary { val, .. } => match String::from_utf8(val) {
                 Ok(s) => Ok(s),
                 Err(err) => Value::binary(err.into_bytes(), span).cant_convert_to("string"),
@@ -2073,183 +2081,183 @@ impl PartialOrd for Value {
                 Value::Bool { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Int { .. } => Some(Ordering::Less),
                 Value::Float { .. } => Some(Ordering::Less),
+                Value::String { .. } => Some(Ordering::Less),
+                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Filesize { .. } => Some(Ordering::Less),
                 Value::Duration { .. } => Some(Ordering::Less),
                 Value::Date { .. } => Some(Ordering::Less),
                 Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Record { .. } => Some(Ordering::Less),
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Int { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Float { val: rhs, .. } => compare_floats(*lhs as f64, *rhs),
+                Value::String { .. } => Some(Ordering::Less),
+                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Filesize { .. } => Some(Ordering::Less),
                 Value::Duration { .. } => Some(Ordering::Less),
                 Value::Date { .. } => Some(Ordering::Less),
                 Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Record { .. } => Some(Ordering::Less),
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Float { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { val: rhs, .. } => compare_floats(*lhs, *rhs as f64),
                 Value::Float { val: rhs, .. } => compare_floats(*lhs, *rhs),
+                Value::String { .. } => Some(Ordering::Less),
+                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Filesize { .. } => Some(Ordering::Less),
                 Value::Duration { .. } => Some(Ordering::Less),
                 Value::Date { .. } => Some(Ordering::Less),
                 Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
                 Value::Record { .. } => Some(Ordering::Less),
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
-            },
-            (Value::Filesize { val: lhs, .. }, rhs) => match rhs {
-                Value::Bool { .. } => Some(Ordering::Greater),
-                Value::Int { .. } => Some(Ordering::Greater),
-                Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { val: rhs, .. } => lhs.partial_cmp(rhs),
-                Value::Duration { .. } => Some(Ordering::Less),
-                Value::Date { .. } => Some(Ordering::Less),
-                Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
-                Value::Record { .. } => Some(Ordering::Less),
-                Value::List { .. } => Some(Ordering::Less),
-                Value::Closure { .. } => Some(Ordering::Less),
                 Value::Nothing { .. } => Some(Ordering::Less),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
-            },
-            (Value::Duration { val: lhs, .. }, rhs) => match rhs {
-                Value::Bool { .. } => Some(Ordering::Greater),
-                Value::Int { .. } => Some(Ordering::Greater),
-                Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { val: rhs, .. } => lhs.partial_cmp(rhs),
-                Value::Date { .. } => Some(Ordering::Less),
-                Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
-                Value::Record { .. } => Some(Ordering::Less),
-                Value::List { .. } => Some(Ordering::Less),
-                Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
-            },
-            (Value::Date { val: lhs, .. }, rhs) => match rhs {
-                Value::Bool { .. } => Some(Ordering::Greater),
-                Value::Int { .. } => Some(Ordering::Greater),
-                Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { .. } => Some(Ordering::Greater),
-                Value::Date { val: rhs, .. } => lhs.partial_cmp(rhs),
-                Value::Range { .. } => Some(Ordering::Less),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
-                Value::Record { .. } => Some(Ordering::Less),
-                Value::List { .. } => Some(Ordering::Less),
-                Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
-            },
-            (Value::Range { val: lhs, .. }, rhs) => match rhs {
-                Value::Bool { .. } => Some(Ordering::Greater),
-                Value::Int { .. } => Some(Ordering::Greater),
-                Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { .. } => Some(Ordering::Greater),
-                Value::Date { .. } => Some(Ordering::Greater),
-                Value::Range { val: rhs, .. } => lhs.partial_cmp(rhs),
-                Value::String { .. } => Some(Ordering::Less),
-                Value::Glob { .. } => Some(Ordering::Less),
-                Value::Record { .. } => Some(Ordering::Less),
-                Value::List { .. } => Some(Ordering::Less),
-                Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
             },
             (Value::String { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { .. } => Some(Ordering::Greater),
-                Value::Date { .. } => Some(Ordering::Greater),
-                Value::Range { .. } => Some(Ordering::Greater),
                 Value::String { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Glob { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Filesize { .. } => Some(Ordering::Less),
+                Value::Duration { .. } => Some(Ordering::Less),
+                Value::Date { .. } => Some(Ordering::Less),
+                Value::Range { .. } => Some(Ordering::Less),
                 Value::Record { .. } => Some(Ordering::Less),
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Glob { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { .. } => Some(Ordering::Greater),
-                Value::Date { .. } => Some(Ordering::Greater),
-                Value::Range { .. } => Some(Ordering::Greater),
                 Value::String { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Glob { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Filesize { .. } => Some(Ordering::Less),
+                Value::Duration { .. } => Some(Ordering::Less),
+                Value::Date { .. } => Some(Ordering::Less),
+                Value::Range { .. } => Some(Ordering::Less),
                 Value::Record { .. } => Some(Ordering::Less),
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
+            },
+            (Value::Filesize { val: lhs, .. }, rhs) => match rhs {
+                Value::Bool { .. } => Some(Ordering::Greater),
+                Value::Int { .. } => Some(Ordering::Greater),
+                Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
+                Value::Filesize { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Duration { .. } => Some(Ordering::Less),
+                Value::Date { .. } => Some(Ordering::Less),
+                Value::Range { .. } => Some(Ordering::Less),
+                Value::Record { .. } => Some(Ordering::Less),
+                Value::List { .. } => Some(Ordering::Less),
+                Value::Closure { .. } => Some(Ordering::Less),
+                Value::Error { .. } => Some(Ordering::Less),
+                Value::Binary { .. } => Some(Ordering::Less),
+                Value::CellPath { .. } => Some(Ordering::Less),
+                Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
+            },
+            (Value::Duration { val: lhs, .. }, rhs) => match rhs {
+                Value::Bool { .. } => Some(Ordering::Greater),
+                Value::Int { .. } => Some(Ordering::Greater),
+                Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
+                Value::Filesize { .. } => Some(Ordering::Greater),
+                Value::Duration { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Date { .. } => Some(Ordering::Less),
+                Value::Range { .. } => Some(Ordering::Less),
+                Value::Record { .. } => Some(Ordering::Less),
+                Value::List { .. } => Some(Ordering::Less),
+                Value::Closure { .. } => Some(Ordering::Less),
+                Value::Error { .. } => Some(Ordering::Less),
+                Value::Binary { .. } => Some(Ordering::Less),
+                Value::CellPath { .. } => Some(Ordering::Less),
+                Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
+            },
+            (Value::Date { val: lhs, .. }, rhs) => match rhs {
+                Value::Bool { .. } => Some(Ordering::Greater),
+                Value::Int { .. } => Some(Ordering::Greater),
+                Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
+                Value::Filesize { .. } => Some(Ordering::Greater),
+                Value::Duration { .. } => Some(Ordering::Greater),
+                Value::Date { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Range { .. } => Some(Ordering::Less),
+                Value::Record { .. } => Some(Ordering::Less),
+                Value::List { .. } => Some(Ordering::Less),
+                Value::Closure { .. } => Some(Ordering::Less),
+                Value::Error { .. } => Some(Ordering::Less),
+                Value::Binary { .. } => Some(Ordering::Less),
+                Value::CellPath { .. } => Some(Ordering::Less),
+                Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
+            },
+            (Value::Range { val: lhs, .. }, rhs) => match rhs {
+                Value::Bool { .. } => Some(Ordering::Greater),
+                Value::Int { .. } => Some(Ordering::Greater),
+                Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
+                Value::Filesize { .. } => Some(Ordering::Greater),
+                Value::Duration { .. } => Some(Ordering::Greater),
+                Value::Date { .. } => Some(Ordering::Greater),
+                Value::Range { val: rhs, .. } => lhs.partial_cmp(rhs),
+                Value::Record { .. } => Some(Ordering::Less),
+                Value::List { .. } => Some(Ordering::Less),
+                Value::Closure { .. } => Some(Ordering::Less),
+                Value::Error { .. } => Some(Ordering::Less),
+                Value::Binary { .. } => Some(Ordering::Less),
+                Value::CellPath { .. } => Some(Ordering::Less),
+                Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Record { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { val: rhs, .. } => {
                     // reorder cols and vals to make more logically compare.
                     // more general, if two record have same col and values,
@@ -2279,127 +2287,127 @@ impl PartialOrd for Value {
                 }
                 Value::List { .. } => Some(Ordering::Less),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::List { vals: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { .. } => Some(Ordering::Greater),
                 Value::List { vals: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Closure { .. } => Some(Ordering::Less),
-                Value::Nothing { .. } => Some(Ordering::Less),
                 Value::Error { .. } => Some(Ordering::Less),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Closure { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { .. } => Some(Ordering::Greater),
                 Value::List { .. } => Some(Ordering::Greater),
                 Value::Closure { val: rhs, .. } => lhs.block_id.partial_cmp(&rhs.block_id),
+                Value::Error { .. } => Some(Ordering::Less),
+                Value::Binary { .. } => Some(Ordering::Less),
+                Value::CellPath { .. } => Some(Ordering::Less),
+                Value::Custom { .. } => Some(Ordering::Less),
                 Value::Nothing { .. } => Some(Ordering::Less),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
-            },
-            (Value::Nothing { .. }, rhs) => match rhs {
-                Value::Bool { .. } => Some(Ordering::Greater),
-                Value::Int { .. } => Some(Ordering::Greater),
-                Value::Float { .. } => Some(Ordering::Greater),
-                Value::Filesize { .. } => Some(Ordering::Greater),
-                Value::Duration { .. } => Some(Ordering::Greater),
-                Value::Date { .. } => Some(Ordering::Greater),
-                Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
-                Value::Record { .. } => Some(Ordering::Greater),
-                Value::List { .. } => Some(Ordering::Greater),
-                Value::Closure { .. } => Some(Ordering::Greater),
-                Value::Nothing { .. } => Some(Ordering::Equal),
-                Value::Error { .. } => Some(Ordering::Less),
-                Value::Binary { .. } => Some(Ordering::Less),
-                Value::CellPath { .. } => Some(Ordering::Less),
-                Value::Custom { .. } => Some(Ordering::Less),
             },
             (Value::Error { .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { .. } => Some(Ordering::Greater),
                 Value::List { .. } => Some(Ordering::Greater),
                 Value::Closure { .. } => Some(Ordering::Greater),
-                Value::Nothing { .. } => Some(Ordering::Greater),
                 Value::Error { .. } => Some(Ordering::Equal),
                 Value::Binary { .. } => Some(Ordering::Less),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Binary { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { .. } => Some(Ordering::Greater),
                 Value::List { .. } => Some(Ordering::Greater),
                 Value::Closure { .. } => Some(Ordering::Greater),
-                Value::Nothing { .. } => Some(Ordering::Greater),
                 Value::Error { .. } => Some(Ordering::Greater),
                 Value::Binary { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::CellPath { .. } => Some(Ordering::Less),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::CellPath { val: lhs, .. }, rhs) => match rhs {
                 Value::Bool { .. } => Some(Ordering::Greater),
                 Value::Int { .. } => Some(Ordering::Greater),
                 Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Filesize { .. } => Some(Ordering::Greater),
                 Value::Duration { .. } => Some(Ordering::Greater),
                 Value::Date { .. } => Some(Ordering::Greater),
                 Value::Range { .. } => Some(Ordering::Greater),
-                Value::String { .. } => Some(Ordering::Greater),
-                Value::Glob { .. } => Some(Ordering::Greater),
                 Value::Record { .. } => Some(Ordering::Greater),
                 Value::List { .. } => Some(Ordering::Greater),
                 Value::Closure { .. } => Some(Ordering::Greater),
-                Value::Nothing { .. } => Some(Ordering::Greater),
                 Value::Error { .. } => Some(Ordering::Greater),
                 Value::Binary { .. } => Some(Ordering::Greater),
                 Value::CellPath { val: rhs, .. } => lhs.partial_cmp(rhs),
                 Value::Custom { .. } => Some(Ordering::Less),
+                Value::Nothing { .. } => Some(Ordering::Less),
             },
             (Value::Custom { val: lhs, .. }, rhs) => lhs.partial_cmp(rhs),
+            (Value::Nothing { .. }, rhs) => match rhs {
+                Value::Bool { .. } => Some(Ordering::Greater),
+                Value::Int { .. } => Some(Ordering::Greater),
+                Value::Float { .. } => Some(Ordering::Greater),
+                Value::String { .. } => Some(Ordering::Greater),
+                Value::Glob { .. } => Some(Ordering::Greater),
+                Value::Filesize { .. } => Some(Ordering::Greater),
+                Value::Duration { .. } => Some(Ordering::Greater),
+                Value::Date { .. } => Some(Ordering::Greater),
+                Value::Range { .. } => Some(Ordering::Greater),
+                Value::Record { .. } => Some(Ordering::Greater),
+                Value::List { .. } => Some(Ordering::Greater),
+                Value::Closure { .. } => Some(Ordering::Greater),
+                Value::Error { .. } => Some(Ordering::Greater),
+                Value::Binary { .. } => Some(Ordering::Greater),
+                Value::CellPath { .. } => Some(Ordering::Greater),
+                Value::Custom { .. } => Some(Ordering::Greater),
+                Value::Nothing { .. } => Some(Ordering::Equal),
+            },
         }
     }
 }