Having select-keys on records returning regular maps is *not* inconsistent with preserving the "type" of map in the sense of sorted-map, priority-map, etc.
Here's why: If you think of select-keys as dissoc'ing all the irrelevant keys, that would preserve the type of sorted-map, priority-map, but it would also turn a record into a regular map (because as soon as you dissoc a required key from a record, it turns into a plain map). If you think of select-keys as emptying out *all* the keys, and then building back up with the selected keys (a more accurate representation of what's going on under the covers), it still lends itself to exactly the same model. Emptying out the keys preserves the type of a map, but converts records to regular maps (because that's what already happens when you get rid of required keys from a record). So, I think the behavior that Cedric described is exactly what mental models would predict. Alex Miller has said that he thinks of it as just nebulously selecting some sort of undefined subset of the map, but I think that's far too vague to base the design on. I think the above two mental models are the ones that someone would settle on if they spent a few seconds trying to think about how it's probably implemented. Both predict the same behavior, and that's the "principle of least surprise" we should be targeting. On Fri, Nov 1, 2013 at 2:02 PM, Michael Gardner <gardne...@gmail.com> wrote: > On Nov 1, 2013, at 14:18 , Mark Engelberg <mark.engelb...@gmail.com> > wrote: > > > I'm sure it's possible to imagine both needs, but if you have have a > sorted-map, and you do a select-keys, don't you think the "principle of > least surprise" is for it to stay a sorted-map? > > I'm not sure about that, given how map and similar functions behave. And > with the point Cedric raised about records, I think it's better to have > consistent behavior (always return a regular map). > > -- > -- > 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/groups/opt_out. > -- -- 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/groups/opt_out.
