Given any functor you can get a monad for free! data Free f a = Either a (f (Free f a))
Not sure about unfree, but there are cofree comonads that are pretty closely related, and give you a comonad given a functor: data Cofree f a = (a, f (Cofree f a)) I'm sure the more categorically minded can tell you way more. Hope this helps, Dan 2010/2/27 Günther Schmidt <gue.schm...@web.de> > Hello, > > I see the term "free monad" quite a lot, but don't really see an > explanation what a free monad is. What sets a monad free and why in this day > and age are there unfree monads? > > Günther > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
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