On 18 dec 2006, at 18.22, Stefan O'Rear wrote:
I can't see how such a generalization could look like, especially since "maybe" can be used with arbitrary monad: maybe (fail "Nothing") return
Well, that???s a possible implementation of a maybeToM. The question is: Is it useful enough for a name on it???s own?
I thought it was useful enough in genericserialize:
module Data.Generics.Serialization.Standard ...
-- |Convert a 'Maybe' object into any monad, using the imbedding defined by -- fail and return. fromMaybeM :: Monad m => String -> Maybe a -> m a fromMaybeM st = maybe (fail st) return
I agree that this is useful. Several of my applications and libraries include this somewhere (with different names: maybeM and maybeToM). Though the RHS isn't much shorter than the LHS, unless its name is made shorter. /Björn