Kim-Ee Yeoh wrote:
Seth Gordon wrote:
Functors are a generalization from lists to "things that can be mapped
over" in general, and then monads are a generalization of functors.
Way to go! That way lies true co/monadic enlightenment.
I feel like I still don't understand comonads. Maybe I just need a Zen
comaster to hit me with a costick and then I'll become coenlightened.
Haskell solves the "how can I do I/O in a pure functional language"
problem by *turning the world inside-out*. Instead of taking data from
the mutable outside world, using functions to manipulate it, and
depositing results back into that world, you put your functions into the
IO monad.
But (the illusion of) taking data out from the real world, manipulating it,
and then putting it back is exactly what the monadic-do syntax sugar
accomplishes:
The type system turns the world inside-out and then the do-notation
provides a right-side-in syntax to code functions in the inside-out world.
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
