Variables in pipelines

[Jose]

Let suppose I want to do some operations in a stream of rectangles: rotate
them and finding the intersection of the rotateded rectangles with the
original ones:

            rects.map(r1->rotate(alpha)).tap(r2)->r2.intersection(r1);


Here "tap" refers to the discusion on forEach
http://mail.openjdk.java.net/pipermail/lambda-dev/2012-August/005463.html

The problem is that being r1 a dummy variable, its reference is lost in the
next link of the chain.

It would be possible and desirable to keep the references of the variables
inside a pipeline?. 

Maybe you can use BiMapper to keep trace of another variable, but the code
would be much more cumbersome. 
Not to say if you want to reuse two o more variables along the pipeline.