Thank you Jason, this is indeed a much nicer solution. On Friday, June 24, 2016 at 8:51:26 PM UTC+2, Jason Felice wrote: > > Recursive descent parsers are much smaller for simple cases. Basically, > you write one function per level of precedence, and each tries, greedily, > to consume as much as possible for that level of precedence. e.g. > > (defn parse-level1 ;; + and - > [list] > ... ; calls parse-level2 repeatedly so long as next operator is + or - > [l1-expr remaining-tokens]) > > (defn parse-level2 ;; * and / > ... ; calls parse-level3 repeatedly so long as next operator is * or / > [list] > ... > [l2-expr remaining-tokens]) > > (defn parse-level3 ;; numbers > [list] > (if (number? list) > [(first list) (rest list)])) > > > > On Fri, Jun 24, 2016 at 2:28 PM, Botond Balázs <balazs...@gmail.com > <javascript:>> wrote: > >> Hi, >> >> I'm working through Clojure for the Brave and True and there's a little >> exercise at the end of Chapter 7 >> <http://www.braveclojure.com/read-and-eval/>: >> >> Create an infix function that takes a list like (1 + 3 * 4 - 5) and >>> transforms it into the lists that Clojure needs in order to correctly >>> evaluate the expression using operator precedence rules. >> >> >> I ended up implementing the shunting yard algorithm >> <https://en.wikipedia.org/wiki/Shunting-yard_algorithm> in Clojure to >> solve it (65 lines, many functions), but I have the suspicion that this >> exercise isn't meant to be this complicated and that I'm missing a very >> obvious and elegant solution. What do you think? >> >> Thanks, >> Botond >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com >> <javascript:> >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > >
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