Phil Tomson wrote: > check out this article on artima by Topher Cyl: > http://www.artima.com/rubycs/articles/patterns_sexp_dsls.html Great article. Thanks. :-) -- Dr Jon D Harrop, Flying Frog Consultancy OCaml for Scientists http://www.ffconsultancy.com/products/ocaml_for_scientists/index.html?usenet