nushell/crates/nu-cmd-lang/src
mike 77ca73f414
allow records to have type annotations (#8914)
# Description
follow up to #8529
cleaned up version of #8892 

- the original syntax is okay
```nu
def okay [rec: record] {}
```
- you can now add type annotations for fields if you know
  them before hand
```nu
def okay [rec: record<name: string>] {}
```

- you can specify multiple fields
```nu
def okay [person: record<name: string age: int>] {}

# an optional comma is allowed
def okay [person: record<name: string, age: int>] {}
```

- if annotations are specified, any use of the command will be type
  checked against the specified type
```nu
def unwrap [result: record<ok: bool, value: any>] {}

unwrap {ok: 2, value: "value"}

# errors with

Error: nu::parser::type_mismatch

  × Type mismatch.
   ╭─[entry #4:1:1]
 1 │ unwrap {ok: 2, value: "value"}
   ·         ───────┬─────
   ·                    ╰── expected record<ok: bool, value: any>, found record<ok: int, value: string>
   ╰────
```
> here the error is in the `ok` field, since `any` is coerced into any
type
> as a result `unwrap {ok: true, value: "value"}` is okay

- the key must be a string, either quoted or unquoted
```nu
def err [rec: record<{}: list>] {}

# errors with
Error:
  × `record` type annotations key not string
   ╭─[entry #7:1:1]
 1 │ def unwrap [result: record<{}: bool, value: any>] {}
   ·                            ─┬
   ·                             ╰── must be a string
   ╰────
```

- a key doesn't have to have a type in which case it is assumed to be
`any`
```nu
def okay [person: record<name age>] {}

def okay [person: record<name: string age>] {}
```

- however, if you put a colon, you have to specify a type
```nu
def err [person: record<name: >] {}

# errors with
Error: nu::parser::parse_mismatch

  × Parse mismatch during operation.
   ╭─[entry #12:1:1]
 1 │ def unwrap [res: record<name: >] { $res }
   ·                             ┬
   ·                             ╰── expected type after colon
   ╰────
```

# User-Facing Changes
**[BREAKING CHANGES]**
- this change adds a field to `SyntaxShape::Record` so any plugins that
used it will have to update and include the field. though if you are
unsure of the type the record expects, `SyntaxShape::Record(vec![])`
will suffice
2023-04-26 08:16:55 -05:00
..
core_commands allow records to have type annotations (#8914) 2023-04-26 08:16:55 -05:00
default_context.rs Move CLI related commands to nu-cli (#8832) 2023-04-10 10:56:47 +12:00
example_support.rs Remove old alias implementation (#8797) 2023-04-07 21:09:38 +03:00
example_test.rs Fix closures that use matches. Move 'collect' to core. (#8596) 2023-03-24 22:50:23 +13:00
lib.rs cratification: Example support (#8231) 2023-02-27 13:58:56 -08:00