The Allegro Common Lisp regular expression module as the following features:

• It is compatible with Perl.
• It is fast. The CL-PPCRE test suite executes 35% faster in Allegro than it does in Perl.
• It is thread-safe.
• It is compatible with CL-PPCRE's S-expression syntax.
• It has a similar API to the original Allegro REGEXP module.

Mastering Regular Expressions by Jeffrey Friedl