> I am just a bit confused why I had to use tuple() while the doc Because of the enum, that code was full of errors :/ Got it now: auto groupIndex(Ts...)() { import std.meta; import std.algorithm.comparison : cmp, strcmp = cmp; enum Comp(N1, N2) = strcmp(N1.stringof, N2.stringof); alias sorted = staticSort!(Comp, Ts); return GroupId!sorted.id; }