Scala and Bash in the same file

...or really any other language with C-like comments:

// 2>/dev/null; echo '
println("Hello world!");
/*
# Yes this script does two things.
//' > /dev/null
echo "Hello World!"
# */

How does it work?

// 2>/dev/null; looks like a comment to Scala, but looks like you're attempting to execute the root directory to Bash (but the error message is sent to /dev/null). The 'echo' bit encapsulates all the Scala code, keeping it away from bash, and then Scala happily ignores the parts betwen the /* */.

My first polyglot program!