OCaml Implementation of the Porter Stemming Algorithm
by Erik Arneson <earneson@arnesonium.com>

This package is pretty much a direct port of the algorithm
implementation in stemmerC_impl.c.  The OCaml implementation is not
optimized and certainly doesn't take advantage of some of the string
manipulation tricks that the C implementation uses.

Usage is extremely simple.  There is only one entry point, that being
the "stem" function.  There is not a lot of documentation and I'm
afraid the code is not well-commented either, but the C implementation
*is* commented and it should be rather simple to follow along.

Things left to do:

* There is little or no bounds checking.  Words of any length can be
  passed in, whereas the C implementation limits input to 1000
  characters.

* The algorithm should throw exceptions when it fails.  Currently, it
  doesn't.

* The C implementation makes sure that words are purely composed of
  letters.  The OCaml implementation doesn't.  I don't know that this
  will always be a problem.

* This implementation only works on the English language.  There are
  Perl implementations which seem to have collections of rules for
  several other languages, but as I am not proficient in those
  languages I'm not going to try to port stemming algorithms for them.

By the way, for speed-critical applications the C implementation may
be quite a bit faster (I haven't done any benchmarking).  For those
who are interested, the StemmerC module, which is not installed by
default, contains wrapper functions around such.

Feedback, bug reports, and patches are most welcome.