Re: memoization in Ada? Hash ADT?

[Kenneth Wolcott <kennethwolcott@gmail.com>]

On Friday, July 21, 2023 at 8:50:06 PM UTC-7, Kenneth Wolcott wrote:
> Hi; 
> 
> I'm working on the Rosetta Code task: 
> 
> "Stirling numbers of the second kind" 
> 
> I have a working recursive solution written in Ada but I'd like to memoize it to cut down on the redundant and duplicative calls (similar to a recursive solution to calculating the Fibonacci sequence). 
> 
> So I think I need a hash ADT (which I've used in Perl) but I've never used in Ada. 
> 
> So I want to preserve the calculation of the Stirling2 for each N and K so I can do a lookup. If this were based on a single unsigned integer, an array would suffice. Maybe a 2d array would suffice? 
> 
> Thanks, 
> Ken Wolcott

I solved the specific problem using a 2d array for caching.  This is not memoization, per se, but this works very well.  The recursive calls are now very fast as there is a maximum of one calculation per recursive call.

So, any resources on how to write Ada programs that take advantage of memoization?

Thanks,
Ken