Ooo -- postwalk-replace, which I didn't know about, is much better than what I was going to suggest! But since this still might be of some interest to the OP here is the message I had composed before ajuc's message came through:
--- Setq doesn't do that in Lisp, but subst does. I've defined subst in Clojure as follows, using the zipper library which I make available by including (:require [clojure.zip :as zip]) in my namespace declaration. I guess you could use "use" instead and avoid the "zip/" prefixes. BTW if you're doing genetic programming in Clojure then you might want to take a look at my Clojure genetic programming system (http://hampshire.edu/lspector/clojush/) although that evolves Push programs rather than standard s-expressions. (defn subst "Returns the given list but with all instances of this (at any depth) replaced with that." [this that lst] ; must traverse twice, using a unique token as an intermediary, to avoid non-termination ; with cases like (subst '(a b c) 'b '(a b c)) (let [unique-token (gensym) with-token (loop [loc (zip/seq-zip lst)] (if (zip/end? loc) (zip/root loc) (recur (zip/next (if (= (zip/node loc) that) (zip/replace loc unique-token) loc)))))] (loop [loc (zip/seq-zip with-token)] (if (zip/end? loc) (zip/root loc) (recur (zip/next (if (= (zip/node loc) unique-token) (zip/replace loc this) loc))))))) --- -Lee On May 14, 2010, at 8:17 AM, ajuc wrote: > Setq isn't functional - equivalent in clojure would be def, but it > isn't meant to be used in that way. > > For your purpose there is better fit: postwalk-replace > > http://richhickey.github.com/clojure/clojure.walk-api.html#clojure.walk/postwalk-replace > > Greetings. > -- Lee Spector, Professor of Computer Science School of Cognitive Science, Hampshire College 893 West Street, Amherst, MA 01002-3359 lspec...@hampshire.edu, http://hampshire.edu/lspector/ Phone: 413-559-5352, Fax: 413-559-5438 Check out Genetic Programming and Evolvable Machines: http://www.springer.com/10710 - http://gpemjournal.blogspot.com/ -- 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
