[Haskell-cafe] ANNOUNCE: Utrecht Haskell Compiler (UHC) -- first release

[wren ng thornton]

Bulat Ziganshin wrote:
> Hello R.A.,
> 
> Sunday, April 19, 2009, 11:46:53 PM, you wrote:
> 
>> Does anybody know if there are any plans to incorporate some of
>> these extensions into GHC - specifically the existential typing ?
> 
> it is already here, but you should use "forall" keyword instead odf
> "exists"

More particularly, enable Rank2Types and then for any type lambda F and 
for any type Y which does not capture @a@:

(x :: exists a. F a) ==> (x :: forall a. F a)

(f :: exists a. (F a -> Y)) ==> (f :: (forall a. F a) -> Y)

-- 
Live well,
~wren