On Wed, 06 Jun 2007 09:29:09 -0700, Dmitri O.Kondratiev
Default 'fail' implementation in Monad class will be: *DivBy> divBy 5 0 Loading package haskell98-1.0 ... linking ... done. *** Exception: user error (div by zero)
And when explicitly defining monad as Maybe it will be different: *DivBy> divBy 5 0::Maybe Int Nothing
I am curious if it is possible to 'cast' divBy to List, Identity, other monads? How?
It just works, and you already did it for Maybe. Just provide the type: *Main> divBy 5 0::[Int] [] *Main> divBy 5 1::[Int] [5] Identity fails with a stack overflow, though (GHC 6.6): *Main> divBy 5 0::Identity Int *** Exception: stack overflow *Main> fail "KK" :: Identity () *** Exception: stack overflow *Main> divBy 5 1::Identity Int *** Exception: stack overflow Anyway... JCAB