Hi Edi,

I'm trying to write a lexer where one can use previously defined classes in subsequent regular expressions.  For example you'd be able to do something like this....

(deflexer my-lexer
  (ws           "[ \t\n]")
  (letter       "[a-zA-Z]")
  (word         (:greedy-repetition 0 nil letter)))

To make this work, the deflexer macro substitutes letter for the parse-tree resulting from (parse-string "[a-zA-Z]").  I wrote this before realizing that parse-string was not exported.  Is there another (more future-proof) way to get at the parse-tree for a regex in a way that it can be combined with other trees?

Cheers,
Andy