17:39 >perl -Mstrict -wE "my $s = 42; say $s; ++$s; say $s;"
42
43

17:39 >perl -Mstrict -MConst::Fast -wE "const my $s => 42; say $s; ++$s; say $s;"
42
Modification of a read-only value attempted at -e line 1.

17:39 >