[Haskell] Monad transformer question
Cyril Schmidt
cschmidt at deds.nl
Wed Oct 25 10:02:25 EDT 2006
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
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