For sequential operations, Scala's iterator almost always equals or exceeds the performance of a Java 8 stream. Thus, one should favor iterator (and its richer set of operations) over seqStream for ...

Yammer, which bills itself as the “enterprise social network,” had tapped Scala, a general-purpose, statically typed language on the Java Virtual Machine, for high-performance back-end services.

Scala and Java are so closely related that you can use Java packages in Scala programs. But Scala is not nearly as wordy as Java, which is Java’s chief complaint. But is offers more than just brevity.