On Jan 22, 4:13 pm, Mike Meyer <mwm-keyword-googlegroups. 620...@mired.org> wrote: > On Fri, 22 Jan 2010 10:08:45 +0200 > > > > > > Miron Brezuleanu <mbr...@gmail.com> wrote: > > Hello, > > > On Fri, Jan 22, 2010 at 3:14 AM, ajay gopalakrishnan > > <ajgop...@gmail.com>wrote: > > > > Hi, > > > > I usually debug by adding println statements. How can I achieve the same > > > effect in Clojure. I don't think I can introduce println at arbitrary > > > places > > > to figure out at which step is the algorithm failing. > > > I also use 'do's as others have suggested. Another trick is to add dummy > > variables in lets just to be able to print something. For instance, > > > (let [a 1 > > b 2 > > dummy1 (println "stuff") > > c 3] > > ...) > > > (this could be done by putting the 2 for b in a do and adding the println in > > the do, but that would be more invasive - with the dummy variable, it's just > > add/uncomment or delete/comment out one line). > > Um, I'm surprised that no one has mentioned clojure.contrib.trace. > Given that Clojure is mostly functional, those "debugging" printlns > will mostly be arguments to functions, or values coming out of > them. The trace package lets you evaluate an expression at the repl, > tracing the values in and out of a user-specified set of functions > during the evaluation process. > > That's what I'd consider the idiomatic way to do debugging in a LISP. > > <mike > -- > Mike Meyer <m...@mired.org> http://www.mired.org/consulting.html > Independent Network/Unix/Perforce consultant, email for more information. > > O< ascii ribbon campaign - stop html mail -www.asciiribbon.org
I haven't used c.c.trace since it can't be left in place without a performance hit. It seems like it might be useful at the repl, but I haven't figured out how to make it do anything interesting, e.g.: user=> (defn foo [coll] (reduce + coll)) #'user/bar user=> (defn bar [coll] (map inc coll)) #'user/foo user=> (trace (foo (bar [1 1 1]))) TRACE: 6 6 Given that trace is a function and not a macro, this result isn't surprising. I'm sure there *is* a way to actually trace such a call, but I haven't figured it out. It occurs to me that such functionality might be worth dropping into c.c.logging, something akin to the spy macro. At least then we could leave the code in place. -- 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
