i've noticed a pattern in explanations in clojure that interface and runtime
are related. Is that the point being made here? Make expensive things hard
or at least explicit?
Maybe instead of nth, since that causes controversy,
call it "find-nth" or something?
On Wed, Apr 22, 2009 at 12:58 PM, Victor Rodriguez <vict...@gmail.com>wrote:
>
> 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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