Collectors update (original) (raw)

Brian Goetz brian.goetz at oracle.com
Thu Jan 31 14:37:08 PST 2013

Just throwing this out there: Have we already strongly considered the heretical idea of just naming it reduce()?

Yes. There are a few reasons we leaned towards a different name here.

  1. (Pedagogical): The mutable reduce-like/fold-like methods have a different feel than the more functional analogues.

  2. (Practical): Overloading methods that take the same-shape lambdas causes use-site ambiguity problems. Since there are reduce forms that look suspiciously like collect forms, this was an issue.

It's distinguished from the others by the type it takes (and that's not a lambda-able type so no worries on that front).

No, because there's the multi-arg collect() form. Which is not only useful (collect(ArrayList::new, ArrayList::add, ArrayList::addAll)) but also usefully pedagogically (in that the single-arg collect then becomes clearly a generalization of the three-arg one.)

If we were uncomfortable calling the type accepted Reducer, perhaps there's... MutatingReducer. Bleh.

We had that once! MutableReduce, it was. Though mutableReduceUnordered is a mouthful.

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