Re: [Haskell-cafe] Fibbonachi numbers algorithm work TOO slow.

For a more efficient Haskell implementation of fibonacci numbers, try

fibs :: [Integer] fibs = 1 : 1 : zipWith (+) fibs (tail fibs)

fib n = fibs !! n

This is uglier, but just to keep using just plain recursion: fib = fib' 0 1 where fib' a b 0 = a fib' a b n = fib' b (a+b) (n-1) You may want "fib' a b n | a `seq` b `seq` n `seq` False = undefined" for strictness if the compiler isn't smart enough to figure out (sorry, didn't test it). And, *please* correct me if I said something stupid =). See ya, -- Felipe.