BrainF is a BrainFuck interpreter written in only ~100 lines
Usage: scala BrainFParser "brainfuckline"
Example: $ scala BrainFParser "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."
Hello World

Also, can be used within a scala project (or the interpreter).
Example:
scala> var a = new BrainF
scala> a.parse("++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.")
Hello World

So far, it only handles correctly formatted input, with unmatched brackets failing silently.