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
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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