[Haskell-cafe] Re: Monads that are Comonads and the role of Adjunction

Yitzchak Gale gale at sefer.org
Mon Dec 17 04:34:12 EST 2007


Derek Elkins wrote:
> There is another very closely related adjunction that is less often
> mentioned.
>
> ((-)->C)^op -| (-)->C
> or
> a -> b -> C ~ b -> a -> C
>
> This gives rise to the monad,
> M a = (a -> C) -> C
> this is also exactly the comonad it gives rise to (in the op category
> which ends up being the above monad in the "normal" category).

That looks very like the type of mfix. Is this
related to MonadFix?

Thanks,
Yitz


More information about the Haskell-Cafe mailing list