Instalando Scala 2.11.8 en OSX 10.11.4 El Capitan

Es muy sencillo:

1. Instalar o actualizar brew
2. Instalar cask so aún no lo has hecho
3. brew cask java
4. brew install scala

Y debería verse así:

1. Actualizar Brew

$ brew update
Updated Homebrew from 63dbc7b to f0b70e5.
==> Migrating Homebrew to v0.9.9
remote: Counting objects: 247, done.
remote: Compressing objects: 100% (207/207), done.
remote: Total 247 (delta 128), reused 116 (delta 26), pack-reused 0
Receiving objects: 100% (247/247), 425.43 KiB | 141.00 KiB/s, done.
Resolving deltas: 100% (128/128), completed with 127 local objects.
From https://github.com/Homebrew/brew
 + f0b70e5...aae4479 master -> origin/master(forced update)
HEAD is now at aae4479 formula: deprecate startup_plist.
==> Homebrew has enabled anonymous aggregate user behaviour analytics
Read the analytics documentation (and how to opt-out) here:
https://git.io/brew-analytics
==> Tapping homebrew/core
Cloning into '/usr/local/Library/Taps/homebrew/homebrew-core'...
remote: Counting objects: 3706, done.
remote: Compressing objects: 100% (3586/3586), done.
remote: Total 3706 (delta 14), reused 2541 (delta 10), pack-reused 0
Receiving objects: 100% (3706/3706), 2.86 MiB | 617.00 KiB/s, done.
Resolving deltas: 100% (14/14), done.
Checking connectivity... done.
Tapped 3583 formulae (3,732 files, 8.9M)
Already up-to-date.

2. Instalar Cask

$ brew tap caskroom/cask
==> Tapping caskroom/cask
Cloning into '/usr/local/Library/Taps/caskroom/homebrew-cask'...
remote: Counting objects: 3646, done.
remote: Compressing objects: 100% (3589/3589), done.
remote: Total 3646 (delta 57), reused 812 (delta 35), pack-reused 0
Receiving objects: 100% (3646/3646), 5.95 MiB | 980.00 KiB/s, done.
Resolving deltas: 100% (57/57), done.
Checking connectivity... done.
Tapped 1 formula (3,614 files, 13.7M)

3. Instalar Java 1.8 (1.8.0_92)

$ brew cask install java
==> We need to make Caskroom for the first time at /opt/homebrew-cask/Caskroom
==> We'll set permissions properly so we won't need sudo in the future
Password:
==> Caveats
This Cask makes minor modifications to the JRE to prevent issues with
packaged applications, as discussed here:

  https://bugs.eclipse.org/bugs/show_bug.cgi?id=411361

If your Java application still asks for JRE installation, you might need
to reboot or logout/login.

Installing this Cask means you have AGREED to the Oracle Binary Code
License Agreement for Java SE at

 http://www.oracle.com/technetwork/java/javase/terms/license/index.html

==> Downloading http://download.oracle.com/otn-pub/java/jdk/8u92-b14/jdk-8u92-macosx-x64.dmg
######################################################################## 100.0%
==> Verifying checksum for Cask java
==> Running installer for java; your password may be necessary.
==> Package installers may write to any location; options such as --appdir are ignored.
Password:
==> installer: Package name is JDK 8 Update 92
==> installer: Installing at base path /
==> installer: The install was successful.
?java staged at '/opt/homebrew-cask/Caskroom/java/1.8.0_92-b14' (2 files, 227M)

Verificar que Java haya sido apropiadamente instalado ejecutando:

$ java -version
java version "1.8.0_92"
Java(TM) SE Runtime Environment (build 1.8.0_92-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.92-b14, mixed mode)

4. Instalar el último Scala (2.11.8)

$ brew install scala
==> Downloading https://homebrew.bintray.com/bottles/scala-2.11.8.el_capitan.bottle.tar.gz
######################################################################## 100.0%
==> Pouring scala-2.11.8.el_capitan.bottle.tar.gz
==> Caveats
To use with IntelliJ, set the Scala home to:
  /usr/local/opt/scala/idea

Bash completion has been installed to:
  /usr/local/etc/bash_completion.d
==> Summary
?  /usr/local/Cellar/scala/2.11.8: 51 files, 30.9M

Verificar que Scala haya sido instalado apropiadamente ejecutando:

$ scala -version
Scala code runner version 2.11.8 -- Copyright 2002-2016, LAMP/EPFL

5. Instalar SBT

$ brew install sbt
==> Downloading https://dl.bintray.com/sbt/native-packages/sbt/0.13.11/sbt-0.13.11.tgz
######################################################################## 100.0%
==> Caveats
You can use $SBT_OPTS to pass additional JVM options to SBT:
 SBT_OPTS="-XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=256M"

This formula is now using the standard typesafe sbt launcher script.
Project specific options should be placed in .sbtopts in the root of your project.
Global settings should be placed in /usr/local/etc/sbtopts
==> Summary
?/usr/local/Cellar/sbt/0.13.11: 5 files, 1.2M, built in 9 seconds

Eso es todo.