* add signature information when help on one command
* tell user that one command support operated on cell paths
Also, make type output to be more friendly, like `record<>` should just be `record`
And the same to `table<>`, which should be `table`
* simplify code
* don't show signatures for parser keyword
* update comment
* output arg syntax shape as type, so it's the same as describe command
* fix string when no positional args
* update signature body
* update
* add help signature test
* fix arg output format for composed data type like list or record
* fix clippy
* add comment
* Add failing test that list of ints and floats is List<Number>
* Start defining subtype relation
* Make it possible to declare input and output types for commands
- Enforce them in tests
* Declare input and output types of commands
* Add formatted signatures to `help commands` table
* Revert SyntaxShape::Table -> Type::Table change
* Revert unnecessary derive(Hash) on SyntaxShape
Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>
* input and output tests
* input and output types for dfr
* expression converter
* remove deprecated command
* correct expressions
* cargo clippy
* identifier for ls
* cargo clippy
* type for head and tail expression
* modify full cell path if block
* custom value trait
* functions for custom value trait
* custom trait behind flag
* open dataframe command
* command to-df for basic types
* follow path for dataframe
* dataframe operations
* dataframe not default feature
* custom as default feature
* corrected examples in command
