Not exactly the same problem, but you might like to see an infix implementation from “The Joy of Clojure” by Fogus and Chouser.
http://fogus.me/fun/unfix/infix-src.html The “Joy” code makes intermediate calculations as it goes. I tweaked it a bit to make a data-reader that only does the infix to prefix transformation. That’s probably closer to what you want. https://gist.github.com/miner/5224709 Note: the “Joy” code uses vector notation for grouping. You would have to adapt it to use lists. Here’s the relevant code from my gist, leaving out the data-reader part: (def && #(and % %2)) (def || #(or % %2)) (def ops '[- + * / < > && || =]) (def rank (zipmap ops (iterate inc 1))) (def op? rank) (defn infix [[a b & [c d e & m]]] (cond (vector? a) (recur (list* (infix a) b c d e m)) (vector? c) (recur (list* a b (infix c) d e m)) (op? b) (if (and d (< (rank b 0) (rank d 0))) (recur (list a b (infix (list* c d e m)))) (recur (list* (list b a c) d e m))) :else a)) ;; example (infix '[1 + 3 * 4 - 5]) ;=> (+ 1 (- (* 3 4) 5)) > On Jun 24, 2016, at 2:28 PM, Botond Balázs <balazsbot...@gmail.com> wrote: > > Hi, > > I'm working through Clojure for the Brave and True and there's a little > exercise at the end of Chapter 7: > > 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 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 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 --- 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+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
