Learn to love scan: http://gist.github.com/338682
-Per On Sat, Mar 20, 2010 at 12:13 PM, Douglas Philips <d...@mac.com> wrote: > Hello all, > I'm new to clojure, but not lisp. > I'm looking for a functional way to index/number only some items of a > list. > > For example, I know I can do this (indexed is from the contrib seq_utils > library): > (using a short example to keep it > readable) > (indexed "Now is") > -> ([0 \N] [1 \o] [2 \w] [3 \space] [4 \i] [5 \s]) > > What I would like to do is only index those elements that satisfy some > predicate, such as: > (indexed-pred vowel? "Now is") > -> ([\N] [0 \o] [\w] [\space] [1 \i] [\s]) > > I want the counter to only increment when the predicate is true, so just > filtering out the index on a fully indexed list isn't what I need, it will > leave holes in the numbering. > > > I'd be OK with the return result being: ([nil \N] [0 \o] [nil \w] [nil > \space] [1 \i] [nil \s]) > since a simple map could strip the nils out. > > I can't help feeling that the solution is just on the edge of my > peripheral vision, but I can't see it. > > Thanks, > -Doug > > > P.S. I want to use this to number the instructions in a road rally, where > the sequence of instructions are interspersed with other notes and items. > Numbering the vowels in a string is a nice simplification. > > -- > 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. > -- 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.
