str collect => str join (#6531)

* Initialize join.rs as a copy of collect.rs

* Evolve StrCollect into StrJoin

* Replace 'str collect' with 'str join' everywhere

git ls-files | lines | par-each { |it| sed -i 's,str collect,str join,g' $it }

* Deprecate 'str collect'

* Revert "Deprecate 'str collect'"

This reverts commit 959d14203e.

* Change `str collect` help message to say that it is deprecated

We cannot remove `str collect` currently (i.e. via
`nu_protocol::ShellError::DeprecatedCommand` since a prominent project
uses the API:

b85542c31c/src/virtualenv/activation/nushell/activate.nu (L43)

crates/nu-command/src/strings/char_.rs

@@ -185,7 +185,7 @@ impl Command for Char {
             },
             Example {
                 description: "Output prompt character, newline and a hamburger character",
-                example: r#"echo [(char prompt) (char newline) (char hamburger)] | str collect"#,
+                example: r#"echo [(char prompt) (char newline) (char hamburger)] | str join"#,
                 result: Some(Value::test_string("\u{25b6}\n\u{2261}")),
             },
             Example {

crates/nu-command/src/strings/str_/collect.rs

@@ -25,11 +25,7 @@ impl Command for StrCollect {
     }
 
     fn usage(&self) -> &str {
-        "Concatenate multiple strings into a single string, with an optional separator between each"
-    }
-
-    fn search_terms(&self) -> Vec<&str> {
-        vec!["join", "concatenate"]
+        "'str collect' is deprecated. Please use 'str join' instead."
     }
 
     fn run(

crates/nu-command/src/strings/str_/join.rs

@@ -0,0 +1,106 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, SyntaxShape,
+    Value,
+};
+
+#[derive(Clone)]
+pub struct StrJoin;
+
+impl Command for StrJoin {
+    fn name(&self) -> &str {
+        "str join"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("str join")
+            .optional(
+                "separator",
+                SyntaxShape::String,
+                "optional separator to use when creating string",
+            )
+            .category(Category::Strings)
+    }
+
+    fn usage(&self) -> &str {
+        "Concatenate multiple strings into a single string, with an optional separator between each"
+    }
+
+    fn search_terms(&self) -> Vec<&str> {
+        vec!["collect", "concatenate"]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let separator: Option<String> = call.opt(engine_state, stack, 0)?;
+
+        let config = engine_state.get_config();
+
+        // let output = input.collect_string(&separator.unwrap_or_default(), &config)?;
+        // Hmm, not sure what we actually want. If you don't use debug_string, Date comes out as human readable
+        // which feels funny
+        let mut strings: Vec<String> = vec![];
+
+        for value in input {
+            match value {
+                Value::Error { error } => {
+                    return Err(error);
+                }
+                value => {
+                    strings.push(value.debug_string("\n", config));
+                }
+            }
+        }
+
+        let output = if let Some(separator) = separator {
+            strings.join(&separator)
+        } else {
+            strings.join("")
+        };
+
+        Ok(Value::String {
+            val: output,
+            span: call.head,
+        }
+        .into_pipeline_data())
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Create a string from input",
+                example: "['nu', 'shell'] | str join",
+                result: Some(Value::String {
+                    val: "nushell".to_string(),
+                    span: Span::test_data(),
+                }),
+            },
+            Example {
+                description: "Create a string from input with a separator",
+                example: "['nu', 'shell'] | str join '-'",
+                result: Some(Value::String {
+                    val: "nu-shell".to_string(),
+                    span: Span::test_data(),
+                }),
+            },
+        ]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(StrJoin {})
+    }
+}

crates/nu-command/src/strings/str_/mod.rs

@@ -4,6 +4,7 @@ mod contains;
 mod distance;
 mod ends_with;
 mod index_of;
+mod join;
 mod length;
 mod lpad;
 mod replace;
@@ -19,6 +20,7 @@ pub use contains::SubCommand as StrContains;
 pub use distance::SubCommand as StrDistance;
 pub use ends_with::SubCommand as StrEndswith;
 pub use index_of::SubCommand as StrIndexOf;
+pub use join::*;
 pub use length::SubCommand as StrLength;
 pub use lpad::SubCommand as StrLpad;
 pub use replace::SubCommand as StrReplace;