[Haskell-cafe] mapOfmap & composition
benjamin.franksen at bessy.de
Fri Dec 9 11:45:04 EST 2005
On Friday 09 December 2005 17:31, Christian Maeder wrote:
> raptor wrote:
> > And second why when I try do do function composition i.e. :
> > newf = map . f
> > But this works :
> > newf x = map (f x)
> Does f has constraints? It should work with a type signature.
To elaborate this very short comment: The above definition for newf is
rejected because of the (infamous) monomorphism restriction. Either
supply a type signature or an argument so that Haskell knows you want
to define a function, not data.
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