Re: [Haskell-cafe] Type classes and hFoldr from HList

7 Nov 2005


      Ralf Lammel wrote:
...
What you can do is define a dedicated *type code* for composition.
comp  = hFoldr (undefined::Comp) (id::Int -> Int) test
data Comp
instance Apply Comp (x -> y,y -> z) (x -> z)
 where
  apply _ (f,g) = g . f
That does it!


Thanks,
    
Greg Buchholz