Excerpts from Neil Brown's message of Tue Nov 03 13:45:42 +0100 2009: > Hi, > > I was thinking about some of my code today, and I realised that where I > have an arrow in my code, A b c, the type (A b) is also a functor. The > definition is (see > http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Arrow.html): > > fmap = (^<<) > -- Or, in long form: > fmap f x = arr f <<< x > > Out of curiosity, and since this is a typical haskell-cafe question, > does this definition of fmap hold for all arrows?
Yes, as shown by the 'WrappedArrow' newtype: http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Applicative.html#t%3AWrappedMonad -- Nicolas Pouillard http://nicolaspouillard.fr _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe