On Mon, Dec 14, 2009 at 8:48 AM, Chouser <chou...@gmail.com> wrote: > On Sun, Dec 13, 2009 at 7:07 PM, Mark Triggs <mark.h.tri...@gmail.com> wrote: >> Hi all, >> >> I recently pulled down the latest Clojure master branch and have noticed >> a small change in line-seq's behaviour which breaks some of my code. >> The code in question uses line-seq like this: >> >> (use 'clojure.contrib.duck-streams) >> (with-open [ss (java.net.ServerSocket. 4141)] >> (println (first (line-seq (reader (.accept ss)))))) >> >> If I run this then telnet to the listen port and send a single line: >> >> Trying 127.0.0.1... >> Connected to localhost. >> Escape character is '^]'. >> hi >> >> The above code prints nothing until the *second* line arrives from the >> socket, even though that line isn't required to fulfil my (first ...) >> request. It appears this behaviour changed in patch 284ee8aa in an >> effort to make line-seq return nil (instead of ()) for an empty lazy >> seq. The line-seq definition currently reads: >> >> (defn line-seq >> "Returns the lines of text from rdr as a lazy sequence of strings. >> rdr must implement java.io.BufferedReader." >> [#^java.io.BufferedReader rdr] >> (let [line (. rdr (readLine))] >> (when line >> (lazy-seq (cons line (line-seq rdr)))))) >> >> and when my code above is blocked, it's because my call to 'first' has >> caused the first recursive call to be made, which immediately blocks on >> the now-eagerly-performed readLine for the second line of input. Taking >> the line to be returned out of the lazy-seq seems to fix things for me: >> >> (defn line-seq >> "Returns the lines of text from rdr as a lazy sequence of strings. >> rdr must implement java.io.BufferedReader." >> [#^java.io.BufferedReader rdr] >> (let [line (. rdr (readLine))] >> (when line >> (cons line (lazy-seq (line-seq-new rdr)))))) >> >> and, I think, still preserves the intention of the original change. >> Does that seem reasonable? > > Your analysis and solution seem right to me. Rich, would you > accept a ticket for this? >
Yes, and could someone please check the other functions that were patched similarly? Thanks, Rich -- 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
