./perl6 -e 'my Num $s;for 1e0..1e3 -> Num $i {$s+=1e0/$i**2};say $s'
Nominal type check failed for parameter '$i'; expected Num but got Int
+ instead
[download]

Oops, that's a bug in Rakudo. I've opened a ticket for it. Now that's the second piece of valuable feedback you've given us. Thanks again.

Update: I have fixed this bug, so the code with -> Num $i { ... } will work in the next release.