Divide & Conquer divides, but doesn't conquer

[FeepingCreature]

On Monday, 25 May 2020 at 03:19:51 UTC, Adam D. Ruppe wrote:
> All this was done on a stock DMD64 D Compiler v2.091.1 on 
> linux. Several enhancements were merged to dmd master recently 
> that may change the results btw.
>
> quick test: simple impl: 2s, 1.57G. phobos impl: 2.3s, 1.97G
>
> hand impl: 1.1s, 725M. w/ static if: 1.2s, 775M
>
> Decent time improvement across the board... but the binary got 
> bigger at 6.4M :( (prolly druntime's fault more than anything 
> else but idk, im not focusing on that rn)

Could you also try with this version, please?

template staticMap(alias F, T...)
{
     mixin(staticMapHelper!(T.length));
}

private enum staticMapHelper(size_t length) = 
staticMapHelperGen!(length);

private string staticMapHelperGen(size_t length)()
{
     string res = "alias staticMap = AliasSeq!(";
     static foreach (i; 0 .. length)
     {
         if (i) res ~= ", ";
         res ~= "F!(T[" ~ i.stringof ~ "])";
     }
     res ~= ");";
     return res;
}

static foreach and stringof were used so I didn't have to pull in 
`format` or `to!string`, which had issues in std.meta.

I'm seeing some improvement over 2.086 at least; it should be 
about equivalent to the hand-unrolled version in master.