>perl -le"for (1..2) { print $_++ for 1..2 }"
1
2
1
2

# Disables the "for constant .. constant" optimisation
>perl -le"for (1..2) { print $_++ for (),1..2 }"
1
2
2
3

>perl -le"for (1..2) { map print($_++), 1..2 }"
1
2
2
3