Indeed, the types
foo :: forall a . (Num a) => a -> (Int, Float)
and
foo :: (forall a . (Num a) => a) -> (Int, Float)
are quite different.
The first one say, I (foo) can handle any kind of numeric 'a' you (the
caller) can pick. You (the caller) get to choose exactly what type you
give me.
The
Hello Cristiano,
Thursday, October 8, 2009, 7:14:20 PM, you wrote:
> Could you explain why, under NoMonomorphismRestriction, this typechecks:
> let a = 1 in (a + (1 :: Int),a + (1 :: Float))
> while this not:
> foo :: Num a => a -> (Int,Float)
> foo k = (k + (1 :: Int), k + (1.0 :: Float))
i
