A command envelope whose model slot is narrowed to one known kind.
Structurally a plain CommandEnvelope (the wire and the REPL see no difference); the narrowing is purely compile-time.
CommandEnvelope
Optional
A command envelope whose model slot is narrowed to one known kind.
Structurally a plain
CommandEnvelope(the wire and the REPL see no difference); the narrowing is purely compile-time.