Iterable.zipWith

[Brian Goetz]

Yes, we've discussed zip operations that would produce a BiStream. 
Straightforward enough, just hasn't come near the top of the list yet.

On 5/24/2012 12:53 AM, François Sarradin wrote:
> Hi,
>
> What do you think about adding a kind of zip or zipWith method to the
> Iterable interface?
>
> As a reminder, zipWith is a method that mixes two Iterables with a function
> in a view to produce a third Iterable. More exactly, zipWith takes elements
> of two Iterables one by one and applies a function on them in order to
> produce the elements of the third Iterable. In a sense, it is the inverse
> operation of tee. Notice that the resulting Iterable has as many elements
> as the smallest Iterable.
>
> For example, this is the way you would compose the methods zipWith and
> reduce to have a dot product operator:
>
>          Iterable<Double>  u = Arrays.asList(1.0, 2.0, 3.0);
>          Iterable<Double>  v = Arrays.asList(4.0, 5.0, 6.0);
>
>          double dotProduct = u.zipWith(v, (x, y) ->  x * y).reduce(0.0, (x,
> y) ->  x + y);
>
>          assertEquals(32.0, dotProduct, 1e-7);
>
>
> zipWith is specifically a lazy method. Each element of the result can be
> evaluated independently from the other ones.
>
> A signature for zipWith in Iterables might be:
>
> <T1, T2, U>  Iterable<U>  zipWith(Iterable<T1>  elements1, Iterable<T2>
> elements2, BiMapper<T1, T2, U>  biMapper)
>
>
> Regards,
>
> françois-
>