On Mon, Apr 20, 2009 at 5:17 PM, Hugh Winkler <hwink...@gmail.com> wrote:
>
> On Mon, Apr 20, 2009 at 1:59 PM, David Nolen <dnolen.li...@gmail.com> wrote:
>> Maps aren't ordered so this isn't a good idea anyway.
>
> It's a good idea if you have a sorted map. My example should have used
> sorted-map.
>
>> The reason first/second work is because they call seq on the collection.
>> (key (nth (seq {:a 1 :b 2 :c 3}) 1)) -> :b
>>
>
> Thanks! I think 'nth ought to behave just like 'first and 'second,
> don't you? If it's a good idea for 'first it's a good idea for 'nth.
Probably not. I expect nth on a vector to be much faster than on a
seq. O(1) vs O(n), respectively.
Cheers,
Victor Rodriguez.
>
> [Apologies to all for the several redundant posts on this topic. I've
> been getting rejection messages from Google Groups for no reason].
>
>> On Mon, Apr 20, 2009 at 2:51 PM, hughw <hwink...@gmail.com> wrote:
>>>
>>> Hi all,
>>>
>>> Why should 'first and 'second work on maps, but not 'nth?
>>>
>>> user> (key (first {:a 1 :b 2 :c 3}))
>>> :a
>>> user> (key (nth {:a 1 :b 2 :c 3} 0))
>>> ; Evaluation aborted.
>>>
>>> java.lang.UnsupportedOperationException: nth not supported on this
>>> type: PersistentArrayMap (NO_SOURCE_FILE:0)
>>> [Thrown class clojure.lang.Compiler$CompilerException]
>>>
>>> Thanks,
>>> Hugh
>>>
>>>
>>
>>
>> >
>>
>
>
>
> --
> Hugh Winkler, CEO
> Wellstorm Development
> 31900 Ranch Road 12
> Suite 206
> Dripping Springs, TX 78620
> USA
> http://www.wellstorm.com/
> +1 512 264 3998 x801
>
> >
>
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