This OCaml-library interfaces the PCRE (Perl-compatible regular expression) library which is written in C. it can be used for matching regular expressions which are written in the PERL style. It is reentrant - and thus thread safe. This is not the case with the "Str" module of OCaml, which builds on the GNU "regex"-library. Using reentrant libraries also means more convenience for programmers. They do not have to reason about states in which the library might be in. The high-level functions for replacement and substitution, all implemented in OCaml, are much faster than the ones of the "Str"-module. In fact, when compiled to native code, they even seem to be significantly faster than those of PERL.
WWW: https://github.com/mmottl/pcre-ocaml