I would barely call this a hack at all; it's only a hack under the view that it feels icky to evolve a programming convention into a language construct. Langua

I would barely call this a hack at all; it's only a hack under the view that it feels icky to evolve a programming convention into a language construct. Languages have been treating (parts of) variable names as part of the type system for ages: Fortran, BASIC, Perl, ...