Just to clarify; I think PersistentArrayMap is too naïve:
user=> {1 1 1 1 1 1 2 2}
{1 1, 1 1, 1 1, 2 2}
Also, this is rev 1286 (just prior to lazy-branch merge thingy).
On Tue, Feb 17, 2009 at 8:50 PM, Christian Vest Hansen
<karmazi...@gmail.com> wrote:
> I think I got it :)
>
> The two (swap! a inc) forms are added to the map at read-time - which
> is before they are evaluated. However, since we are associating the
> (swap! a inc) key with a value twice, only the last one counts. So the
> atom is inc'ed to 1 once (because keys can only be in the map once),
> and assoc'ed with the value 2 (because that's the second assoc we're
> doing to the (swap! a inc) form).
>
> The PersistantArrayMap, on the other hand, is more gullible and
> trusting towards the parsed array of forms that the reader presents
> it, and therefor accepts the (swap! a inc) key twice, which in turn
> causes it to evaluate twice; into two different keys with two
> different associations.
>
> On Tue, Feb 17, 2009 at 8:28 PM, Christian Vest Hansen
> <karmazi...@gmail.com> wrote:
>> That's odd.
>>
>> Might you have uncovered a bug regarding:
>>
>> user=> (class {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9})
>> clojure.lang.PersistentHashMap
>> user=> (class {1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8})
>> clojure.lang.PersistentArrayMap
>>
>> While with the atom code we have:
>>
>> user=> (class (let [a (atom 0)] {(swap! a inc) 1 (swap! a inc) 2 3 3 4
>> 4 5 5 6 6 7 7 8 8 9 9}))
>> clojure.lang.PersistentArrayMap
>> user=> (class (let [a (atom 0)] {(swap! a inc) 1 (swap! a inc) 2 3 3 4
>> 4 5 5 6 6 7 7 8 8}))
>> clojure.lang.PersistentArrayMap
>>
>>
>>
>> On Tue, Feb 17, 2009 at 8:03 PM, Christophe Grand <christo...@cgrand.net>
>> wrote:
>>>
>>> While kicking the tires, I encountered this "behavior":
>>>
>>> user=> (let [a (atom 0)] {(swap! a inc) 1 (swap! a inc) 2 3 3 4 4 5 5 6
>>> 6 7 7 8 8 9 9})
>>> {3 3, 4 4, 5 5, 6 6, 7 7, 8 8, 9 9, 1 2}
>>> user=> (let [a (atom 0)] {(swap! a inc) 1 (swap! a inc) 2 3 3 4 4 5 5 6
>>> 6 7 7 8 8})
>>> {1 1, 2 2, 3 3, 4 4, 5 5, 6 6, 7 7, 8 8}
>>>
>>> Granted, it's not casual Clojure code but it's surprising.
>>>
>>> Christophe
>>>
>>> --
>>> Professional: http://cgrand.net/ (fr)
>>> On Clojure: http://clj-me.blogspot.com/ (en)
>>>
>>>
>>>
>>> >>>
>>>
>>
>>
>>
>> --
>> Venlig hilsen / Kind regards,
>> Christian Vest Hansen.
>>
>
>
>
> --
> Venlig hilsen / Kind regards,
> Christian Vest Hansen.
>
--
Venlig hilsen / Kind regards,
Christian Vest Hansen.
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