Malbolge (/mælˈboʊldʒ/) is a public domain esoteric programming language invented by Ben Olmstead in 1998, named after the eighth circle of hell in Dante's Inferno, the Malebolge.

It was specifically designed to be almost impossible to use, via a counter-intuitive "crazy operation", base-three arithmetic, and self-altering code.

[2] It builds on the difficulty of earlier challenging esoteric languages (such as Brainfuck and Befunge) but exaggerates this aspect to an extreme degree, playing on the entangled histories of computer science and encryption.

[2] The first program was not written by a human being; it was generated by a beam search algorithm designed by Andrew Cooke and implemented in Lisp.

[3] Later, Lou Scheffer posted a cryptanalysis of Malbolge and provided a program to copy its input to its output.

[6] Hisashi Iizawa et al. also proposed a guide for programming in Malbolge for the purpose of obfuscation for software protection.

a stands for "accumulator", set to the value written by all write operations on memory and used for standard I/O.

No other rules are changed, and all Malbolge programs that do not reach the memory limit are still completely functional.

The final result tells the interpreter what to do: After each instruction is executed, it gets encrypted (see below) so that it will not do the same thing next time, unless a jump just happened.

They are listed here: These cycles can be used to create loops that do different things each time and that eventually become repetitive.

Lou Scheffer used this idea to create a Malbolge program (included in his cryptanalysis linked below) that repeats anything the user inputs.