I figured out how return-as-a-value made sense only upon realizing that in the following code, fn funny(){ fn f(_x: ()){} f(return); }

I figured out how return-as-a-value made sense only upon realizing that in the following code, fn funny(){ fn f(_x: ()){} f(return); } f() is never called because funny() returns before it gets called. The reason you want return to be coercible to any type is so that you can write something like let x: i32 = if y { 4 } else { return; // type ! coerced into i32 } And you pick the return value of ! because return never actually produces a value that is propagated on at runtime, it immediately exits the function. (Note this all works even with returning a value)