Hm, yes, I might share Eric's intuition.
I think I'm starting to get it, though. It originally sounded to me like "forall a ->" was being introduced as a new syntax for function arguments. In fact, it is a new syntax for quantification -- one that happens to borrow the syntax for function application. And well it might, because the sort of quantification it introduces is one that requires passing the name of a type to the function!
I think the confusion for me is that I've trained myself to think of
`forall` as explicitly introducing an implicit argument, and `->`
as introducing an explicit argument. So the syntax `forall a ->`
looks to me like a contradiction.
On Thu, Dec 3, 2020, at 10:56, Richard Eisenberg wrote:
>
>
> > On Dec 3, 2020, at 10:23 AM, Bryan Richter <b@chreekat.net> wrote:
> >
> > Consider `forall a -> a -> a`. There's still an implicit universal quantification that is assumed, right?
>
> No, there isn't, and I think this is the central point of confusion. A
> function of type `forall a -> a -> a` does work for all types `a`. So I
> think the keyword is appropriate. The only difference is that we must
> state what `a` is explicitly. I thus respectfully disagree