Add a compact lambda syntax

[PoolloverNathan]

Describe the project you are working on

A city-building game (currently the file manager)

Describe the problem or limitation you are having in your project

The func() syntax for a lambda is slightly too verbose, especially compared to JS's () =>.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

This enhancement will add additional syntax for specifying a lambda that is less verbose than the existing syntax.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

# No arguments:
var no_arguments = () ->
  return 1
var no_arguments_oneline = () -> return 1
# No arguments, with implicit return:
var no_arguments_implicit = () => 2
# Arguments:
var one_arg = (a) => a * 2
var one_arg_typed = (a: float) => a * 2
# Argument list can be omitted for 0 arguments:
var no_arguments_no_list = => 2
# Possible other syntax for specifically variable definitions:
#var no_arguments_no_list_var => 2
# Parentheses can be omitted for 1 argument:
var one_arg_no_parentheses = a => a * 2
var one_arg_typed_no_parentheses = a: float => a * 2

If this enhancement will not be used often, can it be worked around with a few lines of script?

Is there a reason why this should be core and not an add-on in the asset library?

As far as I know, it is impossible to modify GDScript syntax with a script or addon.

[AThousandShips]

This was already mentioned and rejected in the original proposal for lambdas #2431

[dalexeev]

• See also: Make lambdas automatically return value of the last expression #5925

vnen:

I personally don't want to add arrow functions because it would be difficult to parse (the => token appears way too late to easily disambiguate).

[KoBeWi]

() => is just 2 characters shorter than func():...
You are basically trading prefix func for suffix =>.

[dalexeev]

I would prefer func (x) => x + 1 (or fn like in PHP) since we can't use arrow functions due to parser limitations. Just removing return without any other difference is a bad idea in my opinion as it adds ambiguity.

[Calinou]

Closing due to lack of support (see reactions on OP).