Finding Scaladoc help, reduceLeft

Question

Say, i am looking to better understand what reduceLeft method does when applied on a Array[String]

The scaladoc says: enter image description here

Ok, i must ask again, what does this method do? And what's more important, if i can't rely on scaladoc to tell me that, where can i find out?

To avoid others wasting their time... there's no significant info in ArrayOps, IndexSeqOptimized, or TraversableOnce, either. And this is one of the most fundamental collection operations! This kind of reference-doc issue is one of the most infuriating things about Scala. — Ed Staub, Jan 07 '13 at 00:42
[Bug reported](https://issues.scala-lang.org/browse/SI-6930), now go vote for it, will you ? — Francois G, Jan 07 '13 at 10:42

score 8 · Accepted Answer · answered Jan 07 '13 at 00:46

Yeah - that Scaladoc entry could probably be more helpful.

Another useful source of documentation is the Scala Documentation site, which has this to say about reduceLeft:

xs reduceLeft op

Apply binary operation op between successive elements of non-empty collection xs, going left to right.

So what it does is reduce a collection to a single value by successively applying a binary operator. Some examples:

scala> Array(1, 2, 3, 4) reduceLeft (_ + _)
res2: Int = 10

scala> Array("foo", "bar", "baz") reduceLeft (_ + _)
res3: String = foobarbaz

what is as binary operation? – KyelJmD Sep 17 '13 at 13:27 — KyelJmD, Sep 17 '13 at 13:27

1 Answers1