There are few steps to follow to have Scala language installed on your Mac. These works for me for scala scala 2.10.1 on Mac OS X 10.6.8.

The easier way to install Scala on Mac is using HomeBrew, but this instruction for those guys, who prefer good-old MacPorts.

Install scala package from MacPorts:

MyLaptop:~ user$ sudo port install scala2.10

Now Scala is installed to /opt/local/share/scala-2.10/ and symlinks to scala jars were created under /opt/local/share/java

Some symlinks are missing so I created them:

cd /opt/local/bin/
sudo ln -s scala-2.10 scala
sudo ln -s scalac-2.10 scala
sudo ln -s scaladoc-2.10 scaladoc
sudo ln -s scalap-2.10 scalap

Verify that scala is installed. Run inTerminal:

MyLaptop:~ user$ scala
Welcome to Scala version 2.10.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_17).
Type in expressions to have them evaluated.
Type :help for more information.

scala> println(123)
123

scala> :q

Ok, that works! Great!

Now it’s time to setup your IDE!