How do I write a generic memoize function?

Question

I\'m writing a function to find triangle numbers and the natural way to write it is recursively:

function triangle (x)
   if x == 0 then return 0 end
   retu         


        

Answer 1

You're also asking the wrong question for your original problem ;)

This is a better way for that case:

triangle(n) = n * (n - 1) / 2

Furthermore, supposing the formula didn't have such a neat solution, memoisation would still be a poor approach here. You'd be better off just writing a simple loop in this case. See this answer for a fuller discussion.