array-map preserving order is a property of its implementation, but not a promise to those who use them.
Adding a key/value pair to an array-map that takes it over a certain threshold size changes its implementation to a hash-map, which in general changes the seq order completely. This is by design, because operations on large hash-maps are move efficient than operations on large array-maps. If you want a map that preserves order, check out the various variants of ordered maps mentioned in the Clojure cheat sheet (although it is not an exhaustive list of such implementations): http://jafingerhut.github.io Check especially the section on Maps, subsection "Create ordered". In particular the 'ordered-map' constructor creates maps that are guaranteed to preserve the order in which keys were inserted for the first time. Andy On Sun, Aug 9, 2015 at 6:28 PM, Young Kim <philo...@gmail.com> wrote: > This works well as excepted. The order of input elements is maintained. > > (into (array-map) [[1 :a] [2 :b] [3 :c] [4 :d] [5 :e] [6 :f] [7 :g] [8 > :h]]) > ; => {1 :a, 2 :b, 3 :c, 4 :d, 5 :e, 6 :f, 7 :g, 8 :h} > > However, as soon as the number of the input elements exceeds 9, the order > is not maintained any more. > > (into (array-map) [[1 :a] [2 :b] [3 :c] [4 :d] [5 :e] [6 :f] [7 :g] [8 :h] > [9 :i]]) > ; => {7 :g, 1 :a, 4 :d, 6 :f, 3 :c, 2 :b, 9 :i, 5 :e, 8 :h} > > Is this a bug or the intended result? > > -- > 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.
