Talk:Absurd Brainfuck

Reverse of brainfuck

Ignoring the input command, this is a TrivialBrainfuckSubstitution in a wibbly-wobbly timey-wimey disguise. For example, < goes left in the past, so if you reverse the arrow of time there, it simply goes right in the normal flow of time. The spooky stuff is input, because it's not a reversible operation. Looking at it with a view to a normal chronological order, it constrains the user to input exactly what the cell currently is (or it's a contradiction) and then sets the cell to an undefined value. That is, if the cell wasn't already undefined. If the user inputs again, then one can just assume that the input was always result of the operations leading up to it from the time it was first undefined. After the second input, the value becomes undefined again. Presumably constraint programming could be used to determine if the value has become known again, such as using [-] to set it to zero no matter what it was. Perhaps an implementation in minikanren is in order... IFcoltransG (talk) 03:33, 17 January 2020 (UTC)