Remove cumulate from Stream interface

[Brian Goetz]

Only if you don't care about parallel, and the whole value of cumulate 
is that prefix shows up everywhere in parallel algorithms.

Plus, your Mapper will violate the to-be-written specs about 
statefulness/side-effects in lambdas passed to functional stream methods.

On 12/5/2012 9:33 AM, Remi Forax wrote:
> I maybe wrong but there is a simple way to implement cumulate() using
> map(),
> so I'm not sure cumulate pull its own weight.
>
> Rémi
>
> public final Stream<U> cumulate(final BinaryOperator<U> operator) {
>      return map(new Mapper<U,U>() {
>          private Object accumulator = NO_VALUE;
>
>          @Override
>          public U map(U element) {
>              Object acc = accumulator;
>              if (acc == NO_VALUE) {
>                  return element;
>              }
>              acc = operator.operate((U)acc, element);
>              accumulator = acc;
>              return (U)acc;
>          }
>      });
>   }