It's worth mentioning that ClojureScript does not have a MapEntry type. Vectors implement IMapEntry using nth:
https://github.com/clojure/clojurescript/blob/master/src/cljs/cljs/core.cljs#L3601-L3605 And empty returns an empty vector: ClojureScript:cljs.user> (empty (first {:a 1})) [] On Saturday, July 19, 2014 10:44:12 PM UTC-4, Mike Fikes wrote: > > I did a little “code archaeology” in an attempt to elucidate what Rich may > had been thinking: > > In mid 2007, some of the persistent collection implementations had an > EMPTY value defined. [1, 2]. (But, of course, no such EMPTY value was > defined for MapEntrys.) > > Around a year later, MapEntrys were revised to participate in the vector > abstraction [3]. > > A couple of months *after* this, “empty” was added to the collection > abstraction [4], and usually implemented in terms of the EMPTY value, and > MapEntry was made to return null. > > My analysis is inconclusive: Making MapEntry return null is logical, given > that there is no EMPTY value to return. But, the MapEntry / vector business > happening prior to this blurs the argument. > > Perhaps the real problem is that not all collections can be emptied, and > thus thus empty shouldn't have been added to the collection abstraction. > (ClojureScript separates out the idea, introducing IEmptyableCollection.) > > [1] > https://github.com/clojure/clojure/commit/12457e7bf29747232bbfda2a0de3b72fbb14f3a9 > [2] > https://github.com/clojure/clojure/commit/4232de83a53e12741252d31aef9cecee5b8981da > [3] > https://github.com/clojure/clojure/commit/978af02b0a7e2b430c917b32b58215edcae2ad2d > [4] > https://github.com/clojure/clojure/commit/697b69fe9c8f5e2e8d40382e70d4ddd490c4a9ee > -- 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.
