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.