[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));   }