Re: [Haskell-beginners] Haskell code optimisation

Thanks Kim for your answer but as far as I understand strict evaluation should save in space as expression is not expanded in terms of thunks,but I can't understand time savings.Can you pls explain strict evaluation? On Friday, December 11, 2015, Kim-Ee wrote:

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 javascript:_e(%7B%7D,'cvml','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

_______________________________________________ Beginners mailing list Beginners@haskell.org javascript:_e(%7B%7D,'cvml','Beginners@haskell.org'); http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners