[Haskell] The FunctorM library
hallgren at cse.ogi.edu
Fri Mar 25 03:38:14 EST 2005
Simon Peyton-Jones wrote:
>| > class Functor f where fmap :: ...
>| > class Functor m => Monad m where
>| > ...the usual stuff...
>| > fmap = liftM
>It seems overkill to have a whole new language feature to deal with one
Perhaps it is...
>For example, what if Functor T *is* defined explicitly, but in a later module?
I guess it would be the same as what happens now if you accidentally
declare the same instance in different modules, i.e., the system would
complain about overlapping instances.
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