Scala 2.10 requires Java 7 (vs Java 8).
Download the Java SE SDK and install.
Verify that Java 1.7 is installed
$ java -version
Accoring to the Spark Overview:
Spark runs on Java 7+, Python 2.6+ and R 3.1+. For the Scala API, Spark 1.6.0 uses Scala 2.10. You will need to use a compatible Scala version (2.10.x).
Install Tapped version of Scala 2.10.5 (old version)
$ brew install homebrew/versions/scala210
Unlink version of Scala 2.11 (if installed)
$ brew unlink scala
Link Tapped version of Scala 2.10.5
$ brew link scala210 --force
Download the latest version of Eclipse (currently Mars) and installl the usual way.
Verify that the JDK 1.7 is correctly found
Through the Eclipse "Install Additional Software" mechnism, install Scala IDE though the update site.
Install the SBT Eclipse Plugin