type determination

[dsmith]

How can I make something like the following work without "Error: 
cannot append type double to type string[]" ?

T[] some_function(T[] var) {
 T[] var2;
 double a = 12.34;
 string b = "hello";

 if(typeof(var).stringof == "double") {
   var2 ~= a;
 }
 if(typeof(var).stringof == "string") {
   var2 ~= b;
 }

...
}