Re: Use of forall as a sigil

3 Dec 2020

      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!

Den tors 3 dec. 2020 18:39Eric Seidel  skrev:
...
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  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