Without the local the original array is changed. Since $_ is aliased to each element the s// changes the original array. Try:

my @x = qw(foo bar CHOP_ME_OFF_foo);
my @y = @x;

my @copies = map { local $_ = $_; s/^CHOP_ME_OFF_//; $_ } @x;
my @changes = map {s/^CHOP_ME_OFF_//; $_ } @y;

print "x @x\ny @y\ncopies @copies\nchanges @changes\n";

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In reply to Re: Why localize $_ in the map block? by adrianh
in thread how could I use map here? by LameNerd

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