Self-modifying Brainfuck

Brainfuck is a useful general purpose procedural programming language, elegant in its simplicity. However, the language uses a "Harvard" architecture, which separates instructions from data. As a result, some programming paradigms which are possible in other languages are impossible in Brainfuck.

Self-modifying Brainfuck extends the Brainfuck language to a von Neumann Architecture, placing the program code on the same "tape" which the program uses to store data. As a result, it is possible to write programs which modify themselves while running. This feature also brings introspection abilities (sometimes called "Reflection" or "Reflectance"), allowing Brainfuck programs to read their own source code.

Source code


Examples can be found here.


The program source code is placed immediately to the "left" of the data pointer's "origin" point (the location of the data pointer at the start of program execution). The source code is inserted left-to-right, so that the last character of the source file is immediately left of the origin. For example, the following program prints the last character of the source file:
In normal Brainfuck, attempting to access data left of the origin will produce undefined results. As a result, Self-Modifying Brainfuck can technically be described as a backwards-compatible derivative of normal Brainfuck. However, some Brainfuck interpreters allow data left of the origin to be accessed. Programs which rely on this behavior may not run correctly as a result of this alternate behavior.
Simon Howard