[Haskell-cafe] collection monads
fis at wiwi.hu-berlin.de
Tue Oct 3 06:55:29 EDT 2006
another beginners question about monads: given the type
| data (Ix x) => Permutation x = Permutation [x]
i wanted to define
| instance Monad Permutation where
| return xs = Permutation xs
but of course nothing about the monad class guarantees xs to be of
type list. the monad class seems unsuitable for holding collections,
and i am inclined to not instantiate permutations.
just to be sure: is there any easy way to do it that i missed?
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