Yes, I am in support of the fact that size=2 vectors now can now have `key` and `val` called on them. This not working prior to Clojure 1.8 was occasionally the reason why I just used `first` and `second` instead of `key` and `val` before since some function transformations could result in size=2 vectors rather than true map entries.
I think that supporting `empty` on MapEntry is weird, as Alex said above. It does sound the same as the record case. The only frustration I have with this change is that not all APersistentVectors really act as a map entry. Only those of size=2 do. So the interface becomes misleading if you try to use it to figure out from a generic standpoint, what things are map entries and what things aren't. The ambiguity is that all vectors look like map entries. I guess you could do the (instance? IMapEntry x) check along with (== 2 (count x)) for the vector case... On Friday, October 16, 2015 at 6:39:50 AM UTC-5, Alex Miller wrote: > > > On Friday, October 16, 2015 at 3:32:43 AM UTC-5, Pierre-Yves Ritschard > wrote: >> >> Hi Mike, >> >> The code at here seems to contradict you: >> >> https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/APersistentVector.java#L448-L460, >> >> >> as does "(key [:a :b])" in the REPL. >> >> The only limitation is that vectors need to be of size two to act as >> IMapEntries (otherwise an IllegalOperation exception is thrown). >> >> The change seems logical and allows key & val to be used more >> generically. >> >> You're right that will fail on code that checks for (instance? >> IMapEntry). >> > > APersistentVector implements IMapEntry, so this doesn't seem correct. > > >> A good alternative - paging Alex Miller - could be for (empty) on a >> MapEntry to return an empty PersistentVector instead of nil, which would >> ensure that calls to (into (empty <map-entry>) (map f <map-entry>)) >> would return a valid map entry (instead of a collection). >> > > It does not make sense to me for empty on a MapEntry to do what you ask > (for similar reasons why empty on a record is not allowed). > > >> I'm happy to create a ticket for this use-case if deemed valid. >> >> Cheers, >> - pyr >> >> >> >> On 10/16/2015 01:28 AM, Mike Rodriguez wrote: >> > Someone else looked at the issue on >> https://github.com/ztellman/riddley/issues/18 >> > >> > This issue makes the current version of riddley, and therefore >> potemkin, not work on Clojure 1.8 beta1 >> > >> > There is a pull request to fix it at >> https://github.com/ztellman/riddley/pull/19 >> > >> > However I am wondering if it is going to affect more places. The >> problem is that in Clojuee 1.8 APersistentVector now implements IMapEntry >> (therefore j.u.Map$Entry as well), but it doesn't implement the key or val >> methods. >> > What is the reason for that change and/or is this a desired side effect >> of the change? >> > >> > -- 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.
