(3+!+)%!+

(3+!+)%!+ is a Turing-incomplete esolang based on Collatz conjecture made by User:Dragoneater67 to show that Turing-completeness is not neccessary for the halting problem to be undecidable.

Overview

There is a single unbounded nonnegative integer accumulator A which is initialized to use input. The program is run in an implicit forever loop. Here is a list of commands:

• % divides A by 2.
• + increments A.
• 3 multiplies A by 3.
• ! decrements A and halts if 0.
• ( skips past matching ) if A is even.
• ) jumps back to start.

Examples

Collatz conjecture

(3+!+)%!+

Looping counter

+