sub op { @^lhs Z+ @^rhs };

say (1,2) [&op] (3,4); # (4 6)

##</code><code>##

my &infix:<op> = { @^lhs Z+ @^rhs };

say (1,2) op (3,4); # (4 6)

##</code><code>##

my &infix:<op> = &[Z+];

say (1,2) op (3,4); # (4 6)