Feature #17292
closed
Hash Shorthand / Punning
Description
Set Literal vs Javascript Object Punning¶
There was a proposal for a Set literal here: https://bugs.ruby-lang.org/issues/16989
set = { 1, 2, 3 }
...but it was brought up that this is similar to the Javascript Object punning, or Object shorthand syntax:
const a = 1, b = 2, c = 3;
const punnedObject = { a, b, c }
// => { a: 1, b: 2, c: 3 }
Proposition: I believe we should use brackets ({}) for a shorthand Hash syntax similar to Javascript.
Hash Punning¶
My first proposal in this feature request is Hash punning, or Hash shorthand:
a = 1
b = 2
c = 3
{ a:, b:, c: }
# => { a: 1, b: 2, c: 3 }
This syntax avoids the ambiguous syntax of empty block ({}) versus empty set ({}), and with the presence of Symbols it introduces a distinct syntax that would be easier to parse against.
One potential issue would be mixed syntax:
{ a:, b: 2 }
# => { a: 1, b: 2 }
Method Punning¶
This syntax can also be used for keyword argument and method call punning:
def method_name(a:, b:, c:)
a + b + c
end
a = 1
b = 2
c = 3
method_name(a:, b:, c:)
# => 6
I believe this existing syntax for required keywords gives credence to the idea of introducing punning to Ruby, as it's very similar to existing syntax, and therefor feels "Ruby-like".
Pattern Matching¶
This syntax is also already present and used in pattern matching, making it already part of the language:
case { x: 1, y: 2 }
in { x:, y: }
{ x:, y: y + 1} # new
else
# ...
end
I believe this further justifies the case for punning syntax.
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