So, which ones are standouts, that definitely seem more useful to DSL implementations specifically?

• autobox derivatives
  • autobox::DateTime::Duration — pretty incredible
  • Term::ANSIColor::Relax — sensible chaining
• Scope::Upper derivatives
  • returning — allows you to create functions that work like return
  • Continuation::Escape
• Devel::Declare derivatives
  • Method::Signatures. Other similar ones:
    • Function::Parameters
    • Method::Signatures::Simple
    • perl5i::Signature
  • Begin::Declare