is there a merge for associative arrays

[bearophile]

Daniel Davidson:

> Is there a way to do something like this and have opApply be 
> called for '+'?
> If so, is it a bad idea?
>
> import std.stdio;
>
> double[string] opApply(string op)(const double[string][] inputs 
> ...)
>   if(op == "+") {
>   double[string] result;
>   foreach( map ; inputs ) {
>     foreach( key, value ; map ) {
>       auto pval = key in result;
>       if(pval) {
>         *pval += value;
>       } else {
>         result[key] = value;
>       }
>     }
>   }
>   return result;
> }
>
> void main() {
>   double[string] a = [ "foo" : 22.2 ];
>   double[string] b = [ "bar" : 22.2 ];
>   double[string] c = [ "bar" : 5 ];
>   auto d = a+b+c;
> }

In D operators need to be defined inside structs/classes.

So write a function, it could have signature as:

TV[TK] mergeAAs(TK, TV)(TV[TK] aas...) {

It seems even fit for Phobos.

Bye,
bearophile