pL first tries anbn: many parses zero \a's; then times has to parse zero \b's; and the parser returns the concatenation of two empty lists. An empty list isn't a failure as far as the parser either is concerned, so it won't try xdny in that case.
On Wednesday, August 22, 2012 5:38:56 PM UTC-7, Alexsandro Soares wrote: > > Hi all, > > I'm using the Parsatron library to build parser combinators. I have the > following definition: > > (defparser anbn [] > (let->> [as (many (char \a)) > bs (times (count as) (char \b))] > (always (concat as bs)))) > > (defparser xdny [] > (let->> [ds (between (char \x) (char \y) > (many (char \d)))] > (always (concat '(\x) ds '(\y))))) > > (defparser pL [] > (either > (anbn) > (xdny))) > > When I use this definition in REPL with some examples, I have: > > user=> (run (pL) "xddy") > () > > user=> (run (pL) "aabb") > (\a \a \b \b) > > user=> (run (xdny) "xddy") > (\x \d \d \y) > > I didn't understand why the first answer is not (\x \d \d \y). The second > and third answers are correct for me. > > Can anyone help me? > > Regards, > Alex > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
