use Regex qw(literal union concat show);

# {a|b}cd{e|f|g}h

show(
    concat(
        concat(
            union(literal("a"), literal("b")),
            literal("cd"),
        ),
        concat(
            union(literal("e"), literal("f"), literal("g")),
            literal("h"),
        ),
    ),
);

__END__
"acdeh"
"bcdeh"
"acdfh"
"acdgh"
"bcdfh"
"bcdgh"