Ok, this much I understand, but I wouldn't call this overloading on return type... It's - clearly - overloading on input type, either implicit (wantarray - I ch

Ok, this much I understand, but I wouldn't call this overloading on return type... It's - clearly - overloading on input type, either implicit (wantarray - I checked the docs, it seems to be a variable set automaticaly depending on context by the interpreter) or explicit, but input type nevertheless. So, the short answer is - as I thought previously - that no, you can't have implicit dispatch on return type in dynamically typed language. Contracts are probably getting close, but you still need a version of apply that will get expected return type and a bunch of functions to introspect (or a macro that would do the same, but let's not wander there, as lispy macro systems are equivalent with static type systems anyway).