Brainfuck is the ungodly creation of Urban Müller, whose goal was apparently to create a Turing-complete language for which he could write the smallest compiler ever, for the Amiga OS 2.0. His compiler was 240 bytes in size. (Though he improved upon this later -- he informed at one point that he had managed to bring it under 200 bytes.)
One evening at Yahoo! office I introduced snit-ram (Rafael Martins) to brainfuck and the next day he came up with a brainfuck calculator. The same day we started this project to build a full abstraction stack from brainfuck up to a higher level language.
A Brainfuck program has an implicit byte pointer, called "the pointer", which is free to move around within an array of integers, initially all set to zero. The pointer itself is initialized to point to the beginning of this array. Although there is no such thing as beginning because the array is actually a circular tape (i.e. the pointer can loop back over and over).
The Brainfuck programming language consists of eight commands, each of which is represented as a single character.
>Increment the pointer.<Decrement the pointer.+Increment the byte at the pointer.-Decrement the byte at the pointer..Output the byte at the pointer.,Input a byte and store it in the byte at the pointer.[Jump forward past the matching ] if the byte at the pointer is zero.]Jump backward to the matching [ unless the byte at the pointer is zero.
The semantics of the Brainfuck commands can also be succinctly expressed in
terms of C, as follows (assuming that p has been previously defined as a
int*):
>becomes++p;<becomes--p;+becomes++*p;-becomes--*p;.becomesputchar(*p);,becomes*p = getchar();[becomeswhile (*p) {]becomes}