() / (()) conversion in curried generic input types

[hooman (Hooman Mehr)]

Here is another thread that might be relevant:

More consistent function types

I wrote this pitch up this morning, but am just now finding the time to get it posted. It's something that I've thought about on and off for a little while but was motivated to get written up today both because of a recent source compatibility issue that was raised (as mentioned in the pitch) and because it has potential ABI impact and thus needs to be addressed in the short term. This was a quick write-up of "pitch" quality, and there is no implementation yet, but I wanted to get something ou…

If was proposing making

func f<T>() -> T { /*...*/ }

sugar for:

func f<T>(_: Void = () ) -> T { /*...*/ }

During Swift 4.0 to 4.1 transition. It meant functions would have from 1 to n arguments, instead of 0 to n.

The argument for it was reducing source breakage resulting from the removal of tuple splat. I was in favor and didn't really understand what was the valid argument against it.