$ perl -Mstrict -wE 'say ++$_ for 1..4;'
2
3
4
5

~
$  perl -Mstrict -wE 'say $_ for map {++$_} 1..4;'
2
3
4
5

##</code><code>##

$ perl -Mstrict -wE 'say $_ for map {++$_} (1, 2, 3, 4);'
Modification of a read-only value attempted at -e line 1.