S06 shows how to define named-only parameters, "marked with a prefix :". But no example shows anything more than a bare parameter name. No type is ever given!
Looking through my copy of STD.pm, I'm baffled, as it seems not to take types in parameter lists at all. So, is it method bytes ( Encoding :$encoding ) returns Int or method bytes ( : Encoding $encoding ) returns Int ? I'm guessing that the latter would be confused with use of : after the invocant, and it follows that method bytes (Encoding :encoding($override_encoding)) returns Int would work.
