Collectors update

[Kevin Bourrillion]

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

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).

It may not be *implemented* functionally, as 'reduce' usually is (to those
users already familiar with the term), but other than that... it's
conceptually very similar.

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

Of the others, I think aggregate(Aggregator) should be on the table.  I
also think collect(Collector) is still on the table.  I don't think it's *
too* bad, but "collect with a collector to get a collection" is pretty
overloaded...



On Wed, Jan 30, 2013 at 12:42 PM, Raab, Donald <Donald.Raab at gs.com> wrote:

> In my opinion, collect should return a collection.  It should not reduce
> to any result.  In the interest of time, here's a stab at an alternative
> list I came up with using the powers of thesaurus yesterday:
>
> into
> gather
> assemble
> summarize
>
> The functionality currently called collect feels more like
> injectInto/inject in Smalltalk/Ruby/Groovy, but nothing is being injected
> into the method collect directly, but by the Collector (the R in
> makeResult()).  InjectInto/inject is the equivalent of foldLeft.  I would
> be less concerned over using injectInto or inject than collect, as at least
> it seems similar enough in that it can return any value, determined by the
> injector (currently called Collector).  But folks here might consider
> injectInto and foldLeft too cryptic, so I decided to just shorten to into
> in the above list.
>
>
> http://groovy.codehaus.org/groovy-jdk/java/util/Collection.html#inject(groovy.lang.Closure)
>
> In the binary release I have (not sure if this is different in current
> source), two of the overloaded versions of the method collect create a
> FoldOp today (a hint), and the Collector interface has a method called
> accumulate and combine and is called MutableReducer in the javadoc.  The
> methods named reduce also create FoldOp instances.  This makes reduce and
> collect seem eerily similar.
>
> I find this a little confusing, but I have tried my best anyway to name
> that which by any other name seems to be more like
> injectInto/mapReduce/foldL/aggregate/etc. to me.
>
> Thoughts?
>
> > >   I will do
> > > my best and find an alternative that everyone else here likes.
> >
> > Thanks.
> >
> > -Doug
>
>


-- 
Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com