Now the first code snippet also seems to work:
$ perl6-m -e 'sub infix:<+-*/>($a, $b) { ( { $a + $b }, { $a - $b }, { $a * $b
}, { $a / $b } )>>.() }; say 5+-*/2;'
7 3 10 2.5
I added a test for that one to S03-metaops/hyper.t with the following commit:
https://github.com/perl6/roast/commit/85bf9926a1
The second example works as well (cmp. also ticket #77670):
$ perl6-m -e 'say ( { 1 + 1 }, { 2 + 2 } )>>.()'
2 4
I assume that the third example is not supposed to work. If that's wrong please
reopen the ticket.
