use Data::Phrasebook;
my $pb = Data::Phrasebook->new( file => 'phrases.txt' );
my $str = $pb->fetch( 'baz', {foo => '${bar}', bar => '${foo}'} );
# $str = 'foo is ${bar} and bar is ${foo}'

##</code><code>##

baz=foo is :foo and bar is :bar