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$ perle 'my %x = qw{0 a 1 b 2 c}; say "$x{0}$x{1}$x{2}"'
abc
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$ perle 'my %x = qw{0 a 1 b 2 c}; say "012" =~ s/([012])/$x{$1}/gr'
abc
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$ perle 'my @x = qw{a b c}; say "$x[0]$x[1]$x[2]"'
abc
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$ perle 'my @x = qw{a b c}; say "012" =~ s/([012])/$x[$1]/gr'
abc
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$ perle 'my %ent = qw{& & < < > >}; say "... < & > ..." =~ s/([&><])/$ent{$1}/gr'
... < & > ...