Onesharp

Onesharp (or 1#) is a minimalistic programming language created as a teaching tool by Larry Moss. It operates on a register machine model, in which instructions can modify registers or control program flow. The language features five fundamental operations: appending 1 or # to a register, jumping forward or backward by a specified number of instructions, and a conditional branching mechanism that removes and examines the first character in a register. Onesharp programs consist entirely of sequences of 1's and #'s.

Syntax

Onesharp (1#) Instruction Set

Instruction	Meaning
1ⁿ#	Append 1 to register n.
1ⁿ##	Append # to register n.
1ⁿ###	Move forward n instructions.
1ⁿ####	Move backward n instructions.
1ⁿ#####	Conditional branching on register n: If empty, move to the next instruction. If the first character is 1, delete it and move forward two lines. If the first character is #, delete it and move forward three lines.

Purpose

Onesharp is introduced through an interactive Jupyter notebook tutorial, which includes an interpreter and step-by-step execution tools written in Python. Users are guided through small programs and exercises demonstrating basic operations. The notebook also provides command-line tools for parsing and running onesharp programs. Moss then uses onesharp to define computability and demonstrate several fundamental results of computability theory.