On Thu, Jul 2, 2009 at 2:04 PM, Laurent PETIT<laurent.pe...@gmail.com> wrote: > > Hi, > > I think you could use recur instead of the direct recursive call,
Great idea! Simply changing "helper" to "recur" works. > 2009/7/2 Mark Volkmann <r.mark.volkm...@gmail.com>: >> >> There is a challenge on the blog of Tony Morris at >> http://dibblego.wordpress.com/2008/09/05/haskell-scala-java-7-functional-java-java/#comment-2460. >> It's a parsing problem for which he compares solutions in Haskell, >> Scala and Java. I added a Clojure solution. I don't know if this is >> the "best" way to solve this with Clojure, but it certainly works. >> Here's my code, including unit tests. >> >> (use 'clojure.test) >> >> (defn- match [prev-char next-char] >> (condp = prev-char >> \( (= next-char \)) >> \[ (= next-char \]) >> false)) >> >> ; Need a better name for this function. >> (defn- helper [s stack] >> (if (empty? s) >> (empty? stack) >> (let [c (first s) >> top (first stack) >> stack (if (match top c) (next stack) (cons c stack))] >> (helper (next s) stack)))) >> >> (defn balanced? [s] (helper s '())) >> >> (doseq [arg *command-line-args*] >> (println (balanced? arg))) >> >> (deftest match-test >> (is (match \( \))) >> (is (match \[ \])) >> (is (not (match \( \{)))) >> >> (deftest balanced-test >> (is (balanced? "()")) >> (is (balanced? "[]")) >> (is (balanced? "([])")) >> (is (balanced? "[()]")) >> (is (balanced? "[]()")) >> (is (balanced? "[][[([])]]")) >> (is (not (balanced? "("))) >> (is (not (balanced? ")"))) >> (is (not (balanced? "["))) >> (is (not (balanced? "]"))) >> (is (not (balanced? "]["))) >> (is (not (balanced? ")("))) >> (is (not (balanced? "( )"))) >> (is (not (balanced? "([)"))) >> (is (not (balanced? "[)]"))) >> (is (not (balanced? "([)]"))) >> (is (not (balanced? "({})"))) >> (is (not (balanced? "[())]")))) >> >> (run-tests) -- R. Mark Volkmann Object Computing, Inc. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
