I'm not overly familiar with clojure.walk, but I think you'll find the output of (prewalk #(doto % prn) [[3 [3]] [3 3]]) very illuminating.
On Fri, Mar 19, 2010 at 2:13 PM, cej38 <junkerme...@gmail.com> wrote: > This post has two parts. > > Part 1. > > I know that the API is trying to hit the sweet spot on the brevity vs. > information curve, but there are several areas where more information > is needed; one of these is clojure.walk. > > Let's say that I have some nested set of vectors: > (def nestV [ [0 [0] ] [0 0] ]) > and I want to apply > #(+ % 3) > to each element and get out a nested set of vectors with the same > shape as nestV > [ [3 [3] ] [3 3]]. > > The overview to clojure.walk says the following: "It takes any data > structure (list, vector, map, set, seq), calls a function on every > element, and uses the return value of the function in place of the > original." This sounds like I will find a function within this > namespace that will do what I want. I tried prewalk and postwalk, > which, from the their usage "examples" would appear to be what I want. > > But when I try to test them I find the following: > user=> (prewalk #(+ 3 %) nestV) > #<CompilerException java.lang.ClassCastException: > clojure.lang.PersistentVector (NO_SOURCE_FILE:0)> > user=> (postwalk #(+ 3 %) nestV) > #<CompilerException java.lang.RuntimeException: > java.lang.ClassCastException: clojure.lang.PersistentVector > (NO_SOURCE_FILE:0)> > > The problem with the usage "examples" is that they don't actually show > what the outcome will be. Further, there is no documentation other > than the API on clojure.walk. > > > Part 2 > > Is there a function in the API that allows me to do the type of > calculation I described above? > > user=> (some-function #(+ % 3) nestV) > (((3(3))(3 3)) > > -- > 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 > > To unsubscribe from this group, send email to > clojure+unsubscribegooglegroups.com or reply to this email with the words > "REMOVE ME" as the subject. > -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- 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 To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
