Perhaps having a "map-entry?" predicate that was smarter would be helpful.
On Friday, October 16, 2015 at 9:39:09 AM UTC-5, Mike Rodriguez wrote: > > 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.
