On Thu, 15 May 2014 05:51:14 +0000 via Digitalmars-d <[email protected]> wrote:
> Yep, purity implies memoing. No, it doesn't. _All_ that it means when a function is pure is that it cannot access global or static variables unless they can't be changed after being initialized (e.g. they're immutable, or they're const value types), and it can't call any other functions which aren't pure. It means _nothing_ else. And it _definitely_ has nothing to do with functional purity. Now, combined with other information, you _can_ get functional purity out it - e.g. if all the parameters to a function are immutable, then it _is_ functionally pure, and optimizations requiring functional purity can be done with that function. But by itself, pure means nothing of the sort. So, no, purity does _not_ imply memoization. - Jonathan M Davis
