Have you tried BangPatterns? Compiled with optimization, I get 22 secs. Here's the full program: {-# LANGUAGE BangPatterns #-} f :: Int -> Int -> Int f !m !n | m==0 = n+1 | n==0 = f (m-1) 1 | otherwise = f (m-1) (f m (n-1)) main = putStrLn (show (f 4 1)) -- Kim-Ee On Fri, Dec 11, 2015 at 9:47 PM, Abhishek Kumar <abhishekkmr18@gmail.com> wrote:
I was trying to write below program for ackerman function but it fails (waits too long) for ack(4,1) whereas a recursive C program gives result in 37secs.Can someone pls explain this behaviour and recomend some optimisation.
------haskell code f m n | m==0 =n+1 | n==0 = f (m-1) 1 | otherwise = f (m-1) (f m (n-1))
Thanks Abhishek Kumar
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