Hi all, I've defined a custom vector type and implemented various clj/cljs protocols, but now ended up hitting my head against some weird behaviour with conj (or rather cons, internally). The type defines a 2-element vector-like construct and my cons implementation would simply return a standard clojure.lang.PersistentVector with the given arg added like this:
(deftype Foo [a b] clojure.lang.IPersistentCollection clojure.lang.Indexed clojure.lang.Sequential clojure.lang.ISeq clojure.lang.Seqable clojure.lang.Reversible ;; ... elided seq fn impls... (cons [_ c] [a b c])) However, attempting a conj results in an exception I don't understand: (conj (Foo. 1 2) 3) java.lang.ClassCastException: clojure.lang.PersistentVector cannot be cast to clojure.lang.ISeq at user.Foo.cons (foo.clj:13) user.Foo.cons (foo.clj:-1) clojure.lang.RT.conj (RT.java:562) clojure.core$conj.invoke (core.clj:83) ... As far as I can tell, clojure.core/conj simply calls RT.conj(coll, x), which just calls coll.cons(x): https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/RT.java#L604 static public IPersistentCollection conj(IPersistentCollection coll, Object x){ if(coll == null) return new PersistentList(x); return coll.cons(x); } So where in that call path is there an attempt or requirement to cast to an ISeq? I've been comparing notes (as far as this possible) with the default PersistenVector implementation, but not sure where I'm going wrong here... -- 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.
