RosettaCodeData/Task/Enforced-immutability/Perl-6/enforced-immutability-4.pl6
Ingy döt Net d066446780 langs a-z
2013-04-10 22:43:41 -07:00

14 lines
329 B
Raku

sub sum (Num $x, Num $y) {
$x += $y; # ERROR
}
# Explicitly ask for pass-by-reference semantics
sub addto (Num $x is rw, Num $y) {
$x += $y; # ok, propagated back to caller
}
# Explicitly ask for pass-by-value semantics
sub sum (Num $x is copy, Num $y) {
$x += $y; # ok, but NOT propagated back to caller
$x;
}