On Feb 14, 2010, at 8:58 AM, Laurent PETIT wrote: > 2010/2/14 alux <alu...@googlemail.com>: >> Hello Sean, >> >> thank you for the answer. >> >> I used letfn not for recursive swearing, but for the localness. I >> thought the functions to be so special, >> nobody else will use it, so I put it into conway-PM. Is there a non >> recursive let for functions? > > Hello, > > in this case, you can just use let: > > user=> (let [some-fn (fn [] "hello!")] > (println (some-fn))) > hello! > nil > user=> > > HTH, > > -- > Laurent
FWIW, you can always define functions privately with defn-. I prefer that style. Johnny >> >> Thanks for the hint about Lisppaste, didnt know that. >> >> Regards, alux >> >> >> On 13 Feb., 19:25, Sean Devlin <francoisdev...@gmail.com> wrote: >>> Alux, >>> Welcome to Clojrue! Thanks for posting this example. >>> >>> At first glance I would combine power-of-two? and what-power-of-2 into >>> one fn. Also, I would change the order you wrote the method calls in >>> to favor the .method style >>> >>> (defn power-of-2 >>> "Returns log_2(n) iff n is an exact pwoer of 2. nil otherwise" >>> (if (= (.bitCount (big-int n)) 1) >>> (dec (.bitLength (big-int n)))) >>> >>> Also, letfn is for mutually recursive fns (you know, the kind that >>> swear at each other :). I would move big-int, step & power-of-2 into >>> their own defns. That should clean up your definition of conway-PM. >>> >>> Sean >>> >>> PS - Do you use github or lisppaste? The general practice is to put >>> code in a pastebin, and simply include a link in the mailing list. >>> >>> On Feb 13, 11:48 am, alux <alu...@googlemail.com> wrote: >>> >>>> Hi, >>> >>>> I just finished my first (very small) Clojure program. I come from >>>> Java, so it will be everything but idiomatic Clojure, so I post it >>>> here and you may give as much criticism as you want. I'm here to >>>> learn. >>> >>>> It implements JHConway prime machine. The program does not want to be >>>> a quick prime generator (the algorithm is interesting but not quick at >>>> all), but it shall be/become a good implementation of this algorithm. >>> >>>> http://www.jstor.org/pss/2690263(Thefirst page is enough to >>>> implement the algorithm, even if the explanation will come on the next >>>> pages only.) >>> >>>> Started like: >>> >>>> (conway-PM) >>> >>>> It came up to 563 after about 6 hours on my 1.2 GHz Centrino ;-) >>> >>>> Thats the program, feel free to tell me stuff (or to ignore me, would >>>> be a lessen too :) >>> >>>> (defn conway-PM [] >>>> (let [ >>>> factors '(17/91 78/85 19/51 23/38 29/33 77/29 95/23 77/19 >>>> 1/17 11/13 >>>> 13/11 15/14 15/2 55/1) >>>> big-int-class (. 999999999999999999999999999999999 >>>> getClass)] >>>> (letfn [ >>>> (big-int [n];"makes a bigint from int, keeps n if >>>> bigint already" >>>> (let [current-class (. n getClass)] >>>> (if (= current-class >>>> big-int-class) n >>>> (. java.math.BigInteger >>>> valueOf n)))) >>>> (power-of-two? [n];"true iff the integer n is an >>>> power of 2." >>>> (= (. (big-int n) bitCount) 1)) >>>> (what-power-of-2 [n];"gets n from 2^n" >>>> (- (. (big-int n) bitLength) 1)) >>>> (step ;"Multiplies with the first factor to give >>>> an integer." >>>> [n, unused-factors] >>>> (let [factor (first unused-factors) >>>> rest-factors (rest >>>> unused-factors) >>>> dummy (* n factor)] >>>> (if (integer? dummy) >>>> dummy >>>> (step n rest-factors))))] >>>> (loop [seed 2] >>>> (let [next (step seed factors)] >>>> (if (power-of-two? next) >>>> (println (what-power-of-2 >>>> next))) >>>> (recur next)))))) >>> >>>> Regards, alux >> >> -- >> 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 > > -- > 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 -- 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
