> > From: Stephen Tetley <stephen.tet...@gmail.com> > > On 6 September 2010 20:18, John Lato <jwl...@gmail.com> wrote: > > > Can you give an example of a Functor that doesn't have pure? I think > it's > > Pointed Functors which are useful; not Functor by itself. > > Strictly speaking is Pair one? The current implementation tacks on monoid. >
Interesting example. I tend not to like implementations which rely on bottoms, so I think I'd agree. In a similar spirit, I would propose Data.Vector.Unboxed.Vector as a Pointed Functor (modulo element restrictions) which is not Applicative, since the necessary element restrictions mean <*> can't be defined. John
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