Defining an alias to an overloaded function

[Boris Carvajal]

On Monday, 20 January 2020 at 22:02:54 UTC, olvy wrote:
> I'm learning D, and as an exercise, I'm trying to define a 
> HashSet that would be a wrapper around an associative array 
> with some dummy value type.

This seems to work:

...
     struct RangeImpl(T) {
         alias byKeyRetType = 
typeof(byKey!(int[T])((int[T]).init));
         byKeyRetType keyRange;
         this(ref int[T] d) {
             keyRange = d.byKey;
         }
         bool empty() {
             return keyRange.empty;
         }
         ...
     }

     RangeImpl!T opSlice() {
         return RangeImpl!T(_dict);
     }
}

void main()
{
     ...
     if (h[].all!(nn => nn < 5)) {
         writeln("less than 5");
     }