In the face of stiff competition, I have updated my Sudoku solver in OCaml 
with a new implementation that is shorter, simpler and faster (although 
nothing like as fast as Alain's):

  http://www.ffconsultancy.com/free/sudoku/

I have also included links to Sudoku solvers written in OCaml by Alain Frisch, 
Pascal Brisset and David Thomas.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Objective CAML for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists