Another workaround: (array-map (java.util.UUID/randomUUID) 1 (java.util.UUID/randomUUID) 2)
On Wed, Jan 4, 2017 at 9:16 PM, Timothy Baldridge <tbaldri...@gmail.com> wrote: > The check is made at read-time, by the time to form gets to the compiler > it's already a hash-map and one of your forms will have been dropped. So > the decision was made to make the reader check. One way you could solve > your problem here is with tagged literals, as the literal would be created, > and therefore the UUID would be unique before you even got to the creation > of the hash-map. > > http://clojure.org/reference/reader#_tagged_literals > > In short though...what should the reader do, it has no clue which of your > two key/value pairs to drop. > > On Wed, Jan 4, 2017 at 9:05 PM, Tianxiang Xiong <tianxiang.xi...@gmail.com > > wrote: > >> Using a Clojure 1.8.0 REPL, I get the following: >> >> user=> {(+ 1 2) 1 (+ 1 2) 2} >> IllegalArgumentException Duplicate key: (+ 1 2) clojure.lang. >> PersistentArrayMap.createWithCheck (PersistentArrayMap.java:71) >> >> It seems that the a check for key equality is made *before* the key is >> evaluated, when they are still strings. >> >> PersistentArrayMap/createWithCheck is as below: >> >> static public PersistentArrayMap createWithCheck(Object[] init){ >> for(int i=0;i< init.length;i += 2) >> { >> for(int j=i+2;j<init.length;j += 2) >> { >> if(equalKey(init[i],init[j])) >> throw new IllegalArgumentException("Duplicate key: " + init[i]); >> } >> } >> return new PersistentArrayMap(init); >> } >> >> The MapReader in LispReader.java seems to pass an Object[] of Strings to >> PersistentArrayMap/createWithCheck. >> >> public static class MapReader extends AFn{ >> public Object invoke(Object reader, Object leftparen, Object opts, Object >> pendingForms) { >> PushbackReader r = (PushbackReader) reader; >> Object[] a = readDelimitedList('}', r, true, opts, >> ensurePending(pendingForms)).toArray(); >> if((a.length & 1) == 1) >> throw Util.runtimeException("Map literal must contain an even number of >> forms"); >> return RT.map(a); >> } >> >> } >> >> >> This behavior is surprising. Is there a reason the map creation process >> works this way? >> >> The above example may seem trivial, since we would have duplicate keys >> after evaluation as well, but consider the generation of random values: >> >> user=> {(java.util.UUID/randomUUID) 1 (java.util.UUID/randomUUID) 2} >> IllegalArgumentException Duplicate key: (java.util.UUID/randomUUID) >> clojure.lang.PersistentArrayMap.createWithCheck >> (PersistentArrayMap.java:71) >> >> >> -- >> 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. >> > > > > -- > “One of the main causes of the fall of the Roman Empire was that–lacking > zero–they had no way to indicate successful termination of their C > programs.” > (Robert Firth) > > -- > 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. > -- 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.
