I missed this in the sequence spec <http://clojure.org/sequences>: When seq is used on native Java arrays, changes to the underlying array will be reflected in the seq - you must copy the source array to get full immutability.
I understand the rationale, still quite shocking. Ambrose On Wed, Oct 22, 2014 at 3:26 PM, Jozef Wagner <jozef.wag...@gmail.com> wrote: > Yes, seqs are presented as persistent collections, so this situation > is quite unfortunate. But in the case of seq over mutable array, I > think practical/performance reasons win over the correctness, which > would require caching of realized items. > > Jozef > > On Wed, Oct 22, 2014 at 7:51 PM, Ambrose Bonnaire-Sergeant > <abonnaireserge...@gmail.com> wrote: > > Sorry, to be specific I'm disturbed by the apparent mutation of an > immutable > > data structure after it has been observed! > > > > Thanks, > > Ambrose > > > > On Wed, Oct 22, 2014 at 12:52 PM, Jozef Wagner <jozef.wag...@gmail.com> > > wrote: > >> > >> Not every ISeq is lazy. In this case the seq is not lazy but is backed > by > >> a mutable array, thus the mentioned behavior. > >> > >> Jozef > >> > >> On Wednesday, October 22, 2014 6:41:34 PM UTC+2, Fluid Dynamics wrote: > >>> > >>> On Wednesday, October 22, 2014 12:10:30 PM UTC-4, Ambrose > >>> Bonnaire-Sergeant wrote: > >>>> > >>>> On Wed, Oct 22, 2014 at 9:32 AM, Fluid Dynamics <a209...@trbvm.com> > >>>> wrote: > >>>>>> > >>>>>> and is guaranteed to always produce the same value for the same > field. > >>>>> > >>>>> > >>>>> Nope: > >>>>> > >>>>> => (def foo (int-array [1 2 2 5 9 3])) > >>>>> #'user/foo > >>>>> => (def bar (seq foo)) > >>>>> #'user/bar > >>>>> => bar > >>>>> (1 2 2 5 9 3) > >>>>> => (aset foo 3 3) > >>>>> 3 > >>>>> => bar > >>>>> (1 2 2 3 9 3) > >>>>> > >>>> > >>>> What is happening here? (seq foo) certainly does not look like > something > >>>> that should extend ISeq from its behaviour. > >>> > >>> > >>> => (instance? clojure.lang.ISeq bar) > >>> true > >>> > > > -- 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.
