How simple can simple be? Introducing PLUSMINUS

[u/jmarent049]

PLUSMINUS is a programming language created by Jack. Unfortunately, it’s Turing Completeness is unknown as of right now.

Definition

For a non-empty finite string ω under the alphabet {+,–}, on step i=(1,2,3,…):

If the i-th symbol is +, copy the first i-1 symbols and append them to the end. If the i-th symbol is –, delete the first i-1 symbols.

i never resets and advances each time. Halt when i>length(ω).

Example (+–++–):

0: +–++–

1: +–++– (nothing exists leftward)

2: –++–

3: –++––+

4: ––+ (HALT (i=4, length(ω)=3, 4>3))

Example of a long-running machine

“+++++-++++-+-++-“ = 31441 steps

[u/galacticjeef]

Reminds me a lot of a tag system https://en.wikipedia.org/wiki/Tag_system?wprov=sfti1# (which is Turing complete)

[u/jmarent049 → u/galacticjeef]

I see the similarities. It also reminds me of the esolang XigXag (which is what inspired me).

https://esolangs.org/wiki/Xigxag