Am Donnerstag, 24. November 2005 21:19 schrieben Sie: > [...] > Here I want to correct a statement I made previously about: > > mplus m1 m2 = do ... > ~(a,s') <- lift (mplus m1' m2') > > In one of my emails to the thread I mentioned m1/m2 and m1'/m2' could > be different Monads so mplus works differently (so that this is not > exactly a recusrive data structure), but even so the lazy pattern > works. The problem is when m1/m2 and m1'/m2' are of the same Monad > type, then the problem of recursive definition comes up and this is > the place lazy patterns are particularly useful.
They cannot belong to the same monad. If s is the state type and m1' and m2' belong to the monad m then m1 and m2 belong to the monad StateT s m. > Thanks, > Fan Best wishes, Wolfgang _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
