use 5.010_000;

eval { say speak('sheep'); };
print $@ if $@;

eval { say speak('monkey'); };
print $@ if $@;

sub speak {
    my $animal = shift;
    state $says = {
        sheep  => 'baa',
        monkey => 'foo',
    };
    die unless defined $says->{$animal};
    return $says->{$animal};
}
__END__
baa
foo