On May 17, 4:35 am, Ken Wesson <kwess...@gmail.com> wrote: > On Mon, May 16, 2011 at 9:44 AM, Fogus <mefo...@gmail.com> wrote: > > Hi Ken, > > > Thanks for this. I agree that a different name would be much more > > clear. > > Here's one from chapter 7. Section 7.1.2, near the end, has: > > "Perhaps you see a familiar pattern: we apply the column-names vector > as a function across a set of indices, building a sequence of its > elements at those indices. This action will return a sequence of the > values of that row for the supplied column names, which is then turned > into a vector so that it can then be used as the sorting function" > > This does not seem to be correct. It seems to be applying the row map > as a function across a seq of column names, building a sequence of its > elements at those column keys. This action will return a sequence of > the values of that row for the supplied column names, which is then > turned into a vector so that it can then be used as the sort key. The > function that *returns* the vector is the sorting function. > > (Interesting that sort will sort vectors, by "lexicographic" ordering. > It doesn't seem to like lists, though, which is odd since the same > rule would naturally apply. (Sure it could hang on infinite seqs, but > so do lots of other functions, such as print and doall. And it could > be implemented, probably fairly easily, to consume only as much of a > seq as was needed to determine the sort position; then it would only > hang if it hit two infinite seqs that were equal, e.g. two copies of > (iterate inc 1).))
Vectors implement Comparable, and lists don't. I don't see any clear reason for this, but patching sort is the wrong answer: instead implement Comparable for lists. -- 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
