[Haskell-beginners] Seeking some clarification...
daniel.is.fischer at googlemail.com
Sun Jun 5 22:06:20 CEST 2011
On Sonntag, 5. Juni 2011, 21:43, Sean Charles wrote:
> I can see that the term 'action' is one I need
> to use more in my head when thinking about monads...
Well, that doesn't fit all Monads either.
Action is great for IO, but not helpful for  or Maybe.
There are several widely used pictures illustrating monads, each fits some
better than others.
The monads-as-containers picture works great for , Maybe (those really
*are* containers) and some more or less related monads. It doesn't really
work well for IO, State, Cont and some more or less related monads.
The monads-as-computations picture works great for Cont, State and some
related monads, less for , Maybe, IO (it does work for those too, just
The problem is that Monad is a very general and abstract concept, capturing
widely different things, which need not have anything except the Monad
structure in common.
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