Looking at the implementation of next and rest in RT.java (see the
methods next and more), the only difference between them is what they
return when the result of calling seq on the argument is null. next
returns null and more returns PersistentList.EMPTY. How does that
relate to eager versus lazy sequences?
Here's the code for those two methods.
static public ISeq next(Object x){
if(x instanceof ISeq)
return ((ISeq) x).next();
ISeq seq = seq(x);
if(seq == null)
return null;
return seq.next();
}
static public ISeq more(Object x){
if(x instanceof ISeq)
return ((ISeq) x).more();
ISeq seq = seq(x);
if(seq == null)
return PersistentList.EMPTY;
return seq.more();
}
On Sun, Aug 9, 2009 at 11:01 AM, Adrian
Cuthbertson<adrian.cuthbert...@gmail.com> wrote:
>
> Hi Rob, have a look at http://clojure.org/sequences and then on that
> page there's a reference to http://clojure.org/lazy, which explains
> the evolution of the lazy/eager sequences. Next is used for eager
> cases (e.g loop/recur) and rest for lazy-seq. Should make sense if you
> check out those references.
>
> Hth, Adrian.
>
> On Sun, Aug 9, 2009 at 5:41 PM, Rob<rob.nikan...@gmail.com> wrote:
>>
>> Hi all,
>>
>> I'm trying to understand the next vs rest functions. I don't see why
>> you want/need both.
--
R. Mark Volkmann
Object Computing, Inc.
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