Primitive streams and optional

[Doug Lea]

On 11/27/12 09:33, Tim Peierls wrote:
> On Nov 26, 2012, at 10:12 PM, Sam Pullara <spullara at gmail.com> wrote:
>
> I still prefer having one method that returns a "thing" that can be used,
> uniformly and in a fluent-like manner, to do determine whether a result is
> available or absent.
>

In which case (as Howard Lovatt almost said on lambda-dev list), you
are either a closet smalltalk programmer, so want ifTrue:/ifFalse blocks,
or a closet lambda-calculus programmer, in which case you want multiple
continuations. Which are almost the same thing!
So maybe you want:

   <U> U withFirst(Predicate<T> p,
                   Function<T,U> ifPresent, Supplier<U> ifAbsent);

in addition to the plain reduction-based version.

> Me, too, if by "thing" you mean "Optional". It solves so many problems:

Tim: I love Optional with Value types. Vastly better than boxing.
I hate it as a half-object/half-value compromise.
If/when Java supports true value types, I will be first in
the "let's do Optional right" line.
But until then, I'm still dead set against it.

-Doug