[Haskell-cafe] Removing polymorphism from type classes (viz. Functor) (Again)

Stephen Tetley stephen.tetley at gmail.com
Sat Aug 14 15:27:51 EDT 2010

The non-type-changing map can be implemented as a type class - in my
graphics lib Wumpus, I call it pointwise:

class Pointwise  sh where
  type Pt sh :: *
  pointwise :: (Pt sh -> Pt sh) -> sh -> sh

I think other people have posted it to the cafe under a different
name, before I did:


If I was doing Wumpus again though, I'd probably do with Pointwise.

Best wishes


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