[swift-evolution] [pitch] Eliminate the "T1 -> T2" syntax, require "(T1) -> T2"

Developer devteam.codafi at gmail.com
Fri Apr 15 02:42:04 CDT 2016

+1.  The only times I've ever had to use this outside of HoFs were dirty, dirty hacks that probably should have used this anyway.  I can stomach an extra bit of syntax everywhere if it means removing an inconsistency in the wider language.

~Robert Widmann

2016/04/15 0:57、Chris Lattner via swift-evolution <swift-evolution at swift.org> のメッセージ:

> We currently accept function type syntax without parentheses, like:
>  Int -> Float
>  String -> ()
> etc.  The original rationale aligned with the fact that we wanted to treat all functions as taking a single parameter (which was often of tuple type) and producing a tuple value (which was sometimes a tuple, in the case of void and multiple return values).  However, we’ve long since moved on from that early design point: there are a number of things that you can only do in a parameter list now (varargs, default args, etc), implicit tuple splat has been removed, and  the compiler has long ago stopped modeling function parameters this way.  Beyond that, it eliminates one potential style war.
> Given all this, I think it makes sense to go for syntactic uniformity between parameter list and function types, and just require parenthesis on the argument list.  The types above can be trivially written as:
>  (Int) -> Float
>  (String) -> ()
> Thoughts?
> -Chris
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