The difference is that the original behavior allowed room to transform the
mutated object into an object which *could* be safely cached in a
"downstream" seq, while the new behavior pumps the iterator through 32
mutations before user-level code has a chance to see it. Contrived example
using the Java standard libary:
Clojure 1.6.0:
(->> (map vector (java.util.EnumSet/allOf java.util.concurrent.TimeUnit)
(range)) (into {}) (java.util.EnumMap.) (.entrySet) (map str) (into []))
#=> ["NANOSECONDS=0" "MICROSECONDS=1" "MILLISECONDS=2" "SECONDS=3"
"MINUTES=4" "HOURS=5" "DAYS=6"]
Clojure 1.7.0-RC1:
(->> (map vector (java.util.EnumSet/allOf java.util.concurrent.TimeUnit)
(range)) (into {}) (java.util.EnumMap.) (.entrySet) (map str) (into []))
#=> ["DAYS=6" "DAYS=6" "DAYS=6" "DAYS=6" "DAYS=6" "DAYS=6" "DAYS=6"]
IMHO the latter behavior demonstrates a mismatch where chunked seqs and
iterators are simple incompatible.
On Tue, May 26, 2015 at 5:33 PM Alex Miller <a...@puredanger.com> wrote:
> In what way is it broken? Both before and after wrapped a mutable iterator
> into a caching seq. The new one is different in that it chunks so reads 32
> at a time instead of 1. However combining either with other chunking
> sequence operations would have the same effect which is to say that using
> that mutable iterator with anything else, or having expectations about its
> rate of consumption was as dubious before as it is now.
>
> Unless of course I misunderstand your intent, which possible because I am
> on a phone without easy access to look further at the commit and am going
> by memory.
>
>
>
> On May 26, 2015, at 2:17 PM, Marshall Bockrath-Vandegrift <
> llas...@gmail.com> wrote:
>
> Some of my code is broken by
> commit c47e1bbcfa227723df28d1c9e0a6df2bcb0fecc1, which landed in
> 1.7.0-alpha6 (I lasted tested with -alpha5 and have been unfortunately busy
> since). The culprit is the switch to producing seqs over iterators as
> chunked iterators. This would appear to break seq-based traversal of any
> iterator implementing the not-uncommon Java pattern of mutating and
> re-yielding the same object on each `next()` invocation.
>
> I'm unable to find an existing ticket for this apparent-regression.
> Should I create one, or did I miss the existing ticket, or is there some
> mitigating issue which makes this a non-problem?
>
> Thanks.
>
> -Marshall
>
> On Thu, May 21, 2015 at 12:31 PM Alex Miller <a...@puredanger.com> wrote:
>
>> Clojure 1.7.0-RC1 is now available.
>>
>> Try it via
>> - Download: https://repo1.maven.org/maven2/org/clojure/clojure/1.7.0-RC1/
>> - Leiningen: [org.clojure/clojure "1.7.0-RC1"]
>>
>> The only change since 1.7.0-beta3 is CLJ-1706, which makes reader
>> conditional splicing an error at the top level (previously it would
>> silently drop all but the first spliced element).
>>
>> For a full list of changes since 1.6.0, see:
>> https://github.com/clojure/clojure/blob/master/changes.md
>>
>> Please give it a try and let us know if things are working (or not). The
>> more and quicker feedback we get, the sooner we can release 1.7.0 final!
>>
>> - Alex
>>
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