type variables

[Paul Backus]

On Sunday, 2 August 2020 at 12:31:00 UTC, Stefan Koch wrote:
> Take this for example.
> int[] iota(int start, int finish)
> {
>     int[] result = [];
>     result.length = finish - start;
>     foreach(i;start .. finish)
>     {
>         result[i - start] = i;
>     }
>     return result;
> }
>
> Whereas the recursive function for this,
> is something I do not even want to put on here.
> Because it's way to complicated for this simple task.

In fact, the naive recursive version of iota is actually even 
simpler:

int[] iota(int start, int finish)
{
     if (start > finish)
         return [];
     else
         return [start] ~ iota(start + 1, finish);
}

Again, the problem with this function is not complexity or 
readability, but performance. It performs many unnecessary memory 
allocations, and consumes (finish - start) stack frames instead 
of 1.