Hello haskell-cafe,
now i'm reading Haskell' proposals and found that these two things
considered as different:
http://hackage.haskell.org/trac/haskell-prime/wiki/ExistentialQuantification
http://hackage.haskell.org/trac/haskell-prime/wiki/PolymorphicComponents
can you please explain me what is
[apologies to Bulat for the repeat posting]
On Thu, Sep 21, 2006 at 12:05:23PM +0400, Bulat Ziganshin wrote:
now i'm reading Haskell' proposals and found that these two things
considered as different:
http://hackage.haskell.org/trac/haskell-prime/wiki/ExistentialQuantification
Hello Ross,
Thursday, September 21, 2006, 12:55:40 PM, you wrote:
data Ex = forall a. Num a = Ex a
and
data Po = Po (forall a. Num a = a)
Consider the types of the constructors:
Ex :: forall a. (Num a) = a - Ex
Po :: (forall a. (Num a) = a) - Po
sorry, Ross, can you give me a more
Hello Bullat,
now i'm reading Haskell' proposals and found that these two things
considered as different:
http://hackage.haskell.org/trac/haskell-prime/wiki/ExistentialQuantification
http://hackage.haskell.org/trac/haskell-prime/wiki/PolymorphicComponents
can you please explain me
Hello Bullat,
also, ghc66 adds impredicative polymorphism. how it differs from
unqualified existentials?
I have not tried ghc66, but I think one of the things you should be able to
do and that
is perhaps helpful for understanding existencial is:
myList :: [forall a . Num a = a]