Re: [Haskell-cafe] A question about State Monad and Monad in general

Okay...I think I am beginning to understand. Is it right to assume that "magic" is backed by FFI and cannot be done in "pure" Haskell? On Mon, Jul 19, 2010 at 1:47 PM, Ketil Malde wrote:

C K Kashyap writes:

...

I looked at State Monad yesterday and this question popped into my mind. From what I gather State Monad essentially allows the use of Haskell's do notation to "invisibly" pass around a state. So, does the use of Monadic style fetch us more than syntactic convenience?

At it's heart, monads are "just" syntactic convenience, but like many other syntactic conveniences, allows you to structure your code better. Thus it's more about programmer efficiency than program efficiency. (The "do notation" is syntactic sugar for >>= and >>).

...

Again, if I understand correctly, in Mutable Arrays also, is anything getting modified in place really? If not, what is the real reason for better efficiency?

STArray and IOArrays are "magic", and uses monads to ensure a sequence of execution to allow (and implement) in-place modification. So this gives you better performance in many cases. Don't expect this from generic monads.

-k -- If I haven't seen further, it is by standing in the footprints of giants _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

-- Regards, Kashyap