Brainfuck is a turing complete language with 8 instructions.
Hello World:
>+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.>>>++++++++[<++++>-]
<.>>>++++++++++[<+++++++++>-]<---.<<<<.+++.------.--------.>>+.
Cat:
,[.,]
Just pass a filename to the interpreter:
$ bin/brainfuck examples/hello.b
You can also run the debug command to get a log of all instructions.
$ bin/brainfuck debug examples/hello.b