ranges from associative arrays in D 2

Question

I've just started implementing my first medium scale program in D 2.0 after reading Andrei's book The D Programming Language. One of the first problems I came to was using the std.algorithm library with a built-in associative array. For example:

#!/usr/bin/env rdmd

import std.stdio;
import std.algorithm;

void main()
{
   alias int[string] StringHashmap;

   StringHashmap map1;
   map1["one"] = 1;
   map1["two"] = 2;
   writefln("map1: %s", map1);

   StringHashmap map2;
   map2["two"] = 2;
   map2["three"] = 3;
   writefln("map2: %s", map2);

   auto inter = setIntersection(map1, map2);
}

It seemed a simple enough thing to me, expecting that iterating over the inter would produce the single "two" entry. However, I get this compiler error:

./test.d(20): Error: template std.algorithm.setIntersection(alias less = "a < b",Rs...) if (allSatisfy!(isInputRange,Rs)) does not match any function template declaration

./test.d(20): Error: template std.algorithm.setIntersection(alias less = "a < b",Rs...) if (allSatisfy!(isInputRange,Rs)) cannot deduce template function from argument types !()(int[string],int[string])

I can see that the built-in associative array doesn't seem to provide any version of the range to use with the std algorithms.

Am I missing something? Doing something wrong? If not, is this a glaring omission? Is there some reason why this is properly unavailable?

Answer 1

Use this:

auto inter = setIntersection(map1.keys, map2.keys);