import std;

​

struct NoteOn

{

}

​

struct NoteOff

{

}

​

struct PolyAftertouch

{

}

​

struct ControlChange

{

}

​

struct ProgramChange

{

}

​

struct ChanAftertouch

{

}

​

struct PitchBend

{

}

​

struct None

{

}

​

alias Result = Algebraic!(NoteOn, NoteOff, PolyAftertouch, ControlChange, ProgramChange, ChanAftertouch, PitchBend, None);

​

auto foo(int i)

{

    Result result;

    switch(i)

    {

        case 128: .. case 143: result = NoteOn (); break;

        case 144: .. case 159: result = NoteOff (); break;

        case 160: .. case 175: result = PolyAftertouch (); break;

        case 176: .. case 191: result = ControlChange (); break;

        case 192: .. case 207: result = ProgramChange (); break;

        case 208: .. case 223: result = ChanAftertouch (); break;

        case 224: .. case 239: result = PitchBend (); break;

        default: return Result(None());

    }

    return result;

}

int main()

{

    assert(foo(130) == NoteOn());

    assert(foo(225) == PitchBend());

​

    return 0;

}

​