I've never said I want (empty some-map-entry) to implement IMapEntry.
On Sat, Jul 19, 2014 at 10:55 PM, Mike Thvedt <mike.thv...@gmail.com> wrote: > Is there a reason you want an (empty some-map-entry) to > implment IMapEntry? You can already do ordinary modifications on it where > it loses the type. Not sure why empty should be an exception. IMapEntry > only provides key, val, and java.util.Map.MapEntry, and probably if you're > modifying map entries, you don't mind losing that functionality. > > On Saturday, July 19, 2014 3:04:13 PM UTC-5, Jozef Wagner wrote: > >> While the c.l.MapEntry is a persistent vector, there is no such thing as >> an empty MapEntry persistent vector. Returning empty HAMT persistent vector >> instead is not a good solution, as 2 elements HAMT vector does not >> implement IMapEntry interface. >> >> One approach on how to solve this is in Zach's clj-tuple [1] where every >> 2-tuple automatically implements IMapEntry interface. >> >> [1] https://github.com/ztellman/clj-tuple >> >> Jozef >> >> On Saturday, July 19, 2014 9:49:21 PM UTC+2, puzzler wrote: >> >>> As Mike points out, it does seem that MapEntry is considered a >>> collection and is designed to emulate a vector so that you don't really >>> have to worry about whether you have a MapEntry or a two-element vector >>> (and as he points out, in ClojureScript there really is no distinction >>> between a MapEntry and a vector). >>> >>> With that in mind, I would agree that MapEntry's lack of implementation >>> for empty is most likely an oversight, and ideally should behave as if it >>> were a vector. >>> >>> >>> >>> >>> On Sat, Jul 19, 2014 at 11:46 AM, Mike Fikes <mike...@me.com> wrote: >>> >>>> MapEntry is a collection: >>>> >>>> (coll? (clojure.lang.MapEntry. "a" 1)) >>>> >>>> ;=> true >>>> >>>> >>>> (ancestors (class (clojure.lang.MapEntry. "a" 1))) >>>> >>>> ;=> (a set that includes clojure.lang.IPersistentCollection) >>>> >>>> >>>> The docstring for empty implies it would return an empty MapEntry. But >>>> perhaps since MapEntry is a special collection type that must have a size >>>> exactly equal to 2, empty must return nil. >>>> >>>> >>>> Perhaps ClojureScript will one day introduce a MapEntry type and behave >>>> the same way as Clojure (ClojureScript currently returns a >>>> PersistentVector). >>>> >>>> -- >>>> 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 >>>> >>>> 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 >>>> >>>> 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. >>>> >>>> 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. > -- 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.
