Graham Hutton's paper "A tutorial on the expressiveness and universality of folds", provides a good introduction to folds, and implements the Ackerman function as an example.

Folds were the first stumbling point for me when learning Haskell, and this paper helped me a lot.

On 11 December 2015 at 20:17, 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

_______________________________________________
Beginners mailing list
Beginners@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

Sumit Sahrawat,

Junior - Mathematics and Computing,

Indian Institute of Technology - BHU,

Varanasi, India