Design for collections upgrades

[Rémi Forax]

On 03/14/2011 04:41 PM, Craig P. Motlin wrote:
>
> In the Scalable implementation, both println statements print the same 
> thing. Yes that's confusing, but its very similar to mutating a 
> collection while working with lazy evaluation.
>

No, in Java you will get a fail fast ConcurrentModificationException
if you mutate during a lazy evaluation.

Rémi

> On Mar 14, 2011 10:39 AM, "Rémi Forax" <forax at univ-mlv.fr 
> <mailto:forax at univ-mlv.fr>> wrote:
> > On 03/14/2011 02:30 PM, Craig P. Motlin wrote:
> >> There are two forms of lazy evaluation and I see people using the 
> same term
> >> (Stream) to refer to both. In Scala they are called view and stream 
> and I
> >> was confused about the difference so I asked on Stack Overflow. 
> Basically
> >> the difference is:
> >> In a view elements are recomputed each time they are accessed. In a 
> stream
> >> elements are retained as they are evaluated.
> >>
> >> I think that Java collections ought to support both, which is 
> another reason
> >> I think that eager ought to be the default. See the full 
> explanation here:
> >> 
> http://stackoverflow.com/questions/2282754/what-is-the-difference-between-a-view-and-a-stream
> >
> > Interresting.
> > But memoization is hard to provide when your original collection is 
> mutable:
> >
> > What does this code print ?
> >
> > LinkedList<Integer> list = new LinkedList<>();
> > Collections.addAll(list, 1, 2, 3, 4, 5);
> > List<Integer> list2 = list.asScalaStreamPlease();
> > System.out.println(list2.join(" ")); // the whole list is now memoized
> >
> > list.remove(0); // wink wink
> > System.out.println(list2.join(" "));
> >
> > Rémi
> >
> >