[your code here]

[Joshua Niehus]

Not as fancy as the other submits, but it might be worthy of the 
front page:

import std.stdio, std.traits;
void main(string[] args) {
    auto foo(T)(T n) {
        return delegate(T i) {
            static if (isSomeString!(T))
                auto m = mixin("n ~ i");
            else
                auto m = mixin("n + i");
            return m;
        };
    }
    writeln(foo("Hello")(" World!"));
    writeln(foo(18)(24));   }