Absurd Brainfuck is a Brainfuck-derivative by Tailcalled. It is called 'absurd' because the side effects flow in the opposite direction of the data. In other words, when you change a cell, you change what it *was*, not what it is. This can lead to undecidable scenarios, of course.
Absurd Brainfuck has the commands of Brainfuck, but with a "slightly" different effect.
+ Changes the current cell to be one higher in the past - Changes the current cell to be one lower in the past > Goes to the next cell in the past < Goes to the previous cell in the past . Outputs the current value of the current cell. , Reads a value and puts it in the current cell in the past. [p] Executes p until the value of the current cell is 0.
Absurd Brainfuck has an infinite tape in *both* directions.
It is unknown how powerful Absurd Brainfuck is.