Re: Rationale of return types from subroutines always being nullable?

 > Oh, but it *does* serve a purpose, and it *will* fire under the right 
circumstances!  For instance:
 >
 > $ raku -e 'sub a(--> Int:D) { Int }; a'
 > Type check failed for return value; expected Int:D but got Int (Int)
 >    in sub a at -e line 1
 >    in block <unit> at -e line 1

You are right! I had missed that, it's very obvious in retrospective. 
Now I understand.
Thanks for your help! And for working on Raku :)