[ruby-core:93030] [Ruby trunk Feature#15236] add support for hash shorthand

[lyoneil.de.sire@gmail.com]

Issue #15236 has been updated by ignatiusreza (Ignatius Reza Lesmana).


I was reading the presentation slide for the experimental feature for syntax matching.. in which, there's support for "shorthand" matching with hash, in the form of `{ a: }`.. or, following the examples presented above:

```
def foo(param1:, param2:)
  param + param2
end

param1 = 7
param2 = 42

foo(param1:, param2:)

def respond_with(resource, options)
  meta = extract_meta(resource, options)
  etc = extract_etc(resource, options)

  { resource:, meta:, etc: }
end

# destructuring
{data:, meta:, etc:} = {data: [1,2,3], meta: {mobile: true}, etc: "more info"}
```

I think, this answers the concern mentioned above regarding `{ a }` being confused with a Set instead of Hash.. wydt?

ref: https://speakerdeck.com/k_tsj/pattern-matching-new-feature-in-ruby-2-dot-7?slide=34

----------------------------------------
Feature #15236: add support for hash shorthand
https://bugs.ruby-lang.org/issues/15236#change-78404

* Author: ignatiusreza (Ignatius Reza Lesmana)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
PR in github: https://github.com/ruby/ruby/pull/1990

inspired by javascript support for object literal shorthand notation `{ a }`, which will be expanded into `{ a: a }`..

to avoid ambiguity, this shorthand is only supported when hash is defined with `{ }` notation.. in other situation where the brackets is optional, e.g. function call, we still need to write it in full (`m(a : a)` instead of `m(a)`, or `m(a, b, c: c)` instead of `m(a, b, c)`..



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