[Haskell] Monad transformer question

[Cyril Schmidt]

Lajos,

Point taken, thanks.

My question, though, is not as much about how I speed up my program,
as it is about the behaviour of the ReaderT monad transformer. There
is something I do not understand about it, namely, why does such a
small change in the code change the behaviour so much.

Regards,

Cyril

> Based on what you wrote, I'm not sure that monads are the right answer
> in this situation.  It seems like to me that simple memoization of
> function
> values would yield a purely functional but equally efficient solution.
>
> A typical way to memoize the fibonacci function:
>
> fib = ((map fib' [0 ..]) !!)
>     where
>       fib' 0 = 0
>       fib' 1 = 1
>       fib' n = fib (n - 1) + fib (n - 2)
>
> (It only gives you a speed up if you compile with -O2 though.)
>
> Regards,
>
> Lajos Nagy