Sortle

A programming language based on insertion sort

A Sortle example program (Fibonacci number calculator) being debugged.

Sortle is an esoteric programming language based on string rewriting, insertion sort and regexes. This repo contains a command-line interpreter written in JavaScript and runnable via Node, as well as a browser-based interpreter and debugger that allows stepping through programs one expression at a time.

• Play with the interpreter online
• Sample programs to try

Description of Sortle

Programs consist of lists of named expressions, which are sorted and evaluated from top to bottom. Expressions have no side effects; the result of an expression becomes the new name of the expression, and the list's order is adjusted accordingly.

An expression that renames itself to "" (the null string) is deleted. An expression that renames itself to the name of another expression clobbers (replaces) that expression. When only one expression remains, its name is printed out to the user and the program halts. This is both the only way to end the program and the only form of output.

An expression can use regex to match (and extract parts of) other expressions' names. This is the only way of storing data in Sortle.

• More on Esolang wiki
• Language spec

Implementation notes

Deviations from spec

• Does not implement the form of regex that matches substrings of the expression's own name.
• Integer arithmetic is not modulo 2**32.
• Strings work like JavaScript strings, instead of being a series of bytes.

Clarifications to spec

• Regexes match in reverse sort order, starting with the expression previous to the expression being evaluated.
• If a regex doesn't match, the result is the null string.
• Multiple capturing groups in a regex, like (a.)(c.), are treated as an error.
• If a non-numeric string has to be converted to a number, any leading digits are interpreted as a number and the rest of the string thrown away. If there are no leading digits, the string converts to 0.