Re: [Haskell-cafe] Memoisation

On 2/25/07, Tony Morris wrote:

I have a backtracking algorithm that I need to memoise with. Rather than go into the intricacies of the algorithm, I figure (and hope) the factorial function is trivial enough to point out my problem.

Simply, suppose I wish to calculate the factorial of 10, then "later" the factorial of 5. I have already calculated the factorial of 5, but now I must do it again. I have thought of various ways of preventing this; perhaps passing an Array in a state monad. I'm wondering if there is a general solution for this kind of problem.

Thanks for any tips.

-- Tony Morris

You may be able to glean some ideas from a previous discussion at: http://comments.gmane.org/gmane.comp.lang.haskell.cafe/19623 Bryan Burgers