Make sure you also look at the design document section titled "Multiple constraints": http://design.perl6.org/S12.html#Multiple_constraints http://design.perl6

Make sure you also look at the design document section titled "Multiple constraints": http://design.perl6.org/S12.html#Multiple_constraints http://design.perl6.org/S12.html#Multiple_constraints It concludes with: > As a first approximation for 6.0.0, subsets of enums are static, and other subsets are dynamic. We may refine this in subsequent versions of Perl.