[Haskell-cafe] What are "free" Monads?

[Günther Schmidt]

Hello Daniel,

that looks lovely, but it doesn't help me much :)

Günther

Am 27.02.10 10:06, schrieb Daniel Peebles:
> 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.schmidt at web.de <mailto:gue.schmidt at 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
>
>
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