004 - Hello World in Brainfuck
It doesn’t look like source code at first, but this snippet is actually valid code written in a language called Brainfuck.
Brainfuck supports only 8 commands, each represented with a single character.
These valid commands are: ><+-.,[]. Everything else is ignored.
Brainfuck is considered an esoteric programming language meaning it has no practical purpose and is made for exploratory and research purposes, as a proof of concept or just for fun.
Try it out
You can run the snippet above by following this link.
Explanation
Brainfuck operates on top of a single “data” array and it can only manipulate a
single element at a time, either changing its value or printing it out. > and
< are used to move on to the next or previous element respectively, making
Brainfuck function in a way that’s similar to a Turing machine.
Wikipedia has an in-depth explanation of the Hello World program above.