This works now: $ perl6 -e 'say <a b> X <c d>.map({$_})' a c a d b c b d
$ perl6 -e 'say <a b>.map({$_}) X <c d>' a c a d b c b d $ perl6 -e 'say <a b>.map({$_}) X <c d>.map({$_})' a c a d b c b d I added tests to S03-metaops/cross.t with commit https://github.com/perl6/roast/commit/d3aa62b272 I'm closing this ticket.