Thanks for the advice. I will keep it in mind. Luca
Il giorno mercoledì 14 febbraio 2018 20:05:32 UTC+1, Erik Assum ha scritto: > > There is also https://github.com/magnars/realize/blob/master/README.md which > helps with this problem. > > Erik. > -- > i farta > > 14. feb. 2018 kl. 12:20 skrev Thomas Heller <th.h...@gmail.com > <javascript:>>: > > lazy-seq is the short answer. > > You are constructing the seq inside the try/catch but it is realized > outside of that so no exceptions will be caught. > > (defn gen-ym-list [from to] > (try > (->> (p/periodic-seq (f/parse ym-fmt from) (t/months 1)) > (take-while #(not (t/after? % (f/parse ym-fmt to)))) > (into []) > (catch Exception _ nil))) > > This forces the seq inside the try/catch. > > HTH, > Thomas > > On Wednesday, February 14, 2018 at 11:46:58 AM UTC+1, icamts wrote: >> >> Hi all, >> I found an unexpected behavior of (try ... (catch ...)) special form. >> Can someone help me understand it better? >> >> These are project.clj and core.clj of my test project. The test project >> zip file is provided as an attachment. >> >> (defproject try-try "0.0.0" >> :description "unexpected try beahvior" >> :url "http://example.com/FIXME"; >> :license {:name "Eclipse Public License" >> :url "http://www.eclipse.org/legal/epl-v10.html"} >> :dependencies [[org.clojure/clojure "1.8.0"] >> [org.clojure/tools.cli "0.3.5"] >> [clj-time "0.14.0"] >> [joda-time/joda-time "2.9.7"]]) >> >> (ns try-try.core >> (:require [clj-time.core :as t] >> [clj-time.format :as f] >> [clj-time.periodic :as p])) >> >> (def ym-fmt (f/formatter "yyyyMM")) >> >> (defn gen-ym-list [from to] >> (try >> (->> (p/periodic-seq (f/parse ym-fmt from) (t/months 1)) >> (take-while #(not (t/after? % (f/parse ym-fmt to))))) >> (catch Exception _ nil))) >> >> (defn gen-ym-list* [from to] >> (try >> (let [ym-from (f/parse ym-fmt from) >> ym-to (f/parse ym-fmt to)] >> (->> (p/periodic-seq ym-from (t/months 1)) >> (take-while #(not (t/after? % ym-to))))) >> (catch Exception _ nil))) >> >> (gen-ym-list "2017" "201802"); returns nil as expected >> >> (gen-ym-list "201712" "2018"); throws unexpected exception >> >> (gen-ym-list* "2017" "201802"); returns nil as expected >> >> (gen-ym-list* "201712" "2018"); returns nil as expected >> >> (use 'clojure.walk) >> >> (macroexpand-all >> `(try >> (->> (p/periodic-seq (f/parse ym-fmt from) (t/months 1)) >> (take-while #(not (t/after? % (f/parse ym-fmt to))))) >> (catch Exception _ nil))) >> >> (macroexpand-all >> `(try >> (let [date-from (f/parse ym-fmt from) >> date-to (f/parse ym-fmt to)] >> (->> (p/periodic-seq date-from (t/months 1)) >> (take-while #(not (t/after? % date-to))))) >> (catch Exception _ nil))) >> >> gen-ym-list doesn't catch IllegalArgumentException thrown when to >> argument is malformed. It catches the same exception thrown when from is >> malformed. >> >> gen-ym-list* with arguments parsing in an initial let form works as >> expected. >> >> From macro expansion I can see the to is parsed inside a fn*. Is this a >> known limit in try-catch special form? Or a bug? Thanks in advance for your >> help. >> >> Cheers, >> Luca >> >> >> -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clo...@googlegroups.com <javascript:> > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+u...@googlegroups.com <javascript:> > 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 unsubscribe from this group and stop receiving emails from it, send an > email to clojure+u...@googlegroups.com <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
