#text of code

After yesterday’s piece on the 128 language Quine Relay, I had to follow up with this polyglot program on Stack Overflow’s Code Golf forum, which at the time of writing, works in 191 languages and is still actively updated.

This is the challenge, as described in the post:

The nth program to be submitted must run in n different languages; specifically, all the languages added in previous programs to be submitted, plus one more. The program must output 1 when run in the first language used in answers to this question, 2 when run in the second language, and so on.

Yusuke Endoh has created an astonishing 128 language Ouroborous quine. This Ruby program produces a Rust program, which produces a Scala program, which produces a Scheme program, and so on, progressing through another 124 languages to return to its original state. To understand what this is and how it came to be, we first need to consider the quine.

A quine is a program that prints its own source code to the screen. The term comes from philosopher Willard Van Orman Quine's paradox "Yields falsehood when preceded by its quotation," which fails to yield falsehood when preceded by its quotation, making it neither true nor false. The quine in code is named not in reference to the paradoxical quality of the statement, but to its embedding of the quote in itself, where it acts as both the subject and expression of the sentence. The quine program, likewise, flattens the reading of the program with the running of the program. If one were to print its source code to the screen or execute it, the result is the same.

Since this is a fancy way of saying "it prints its own source code," one might expect such a program to be simple. However, even concise quines in fairly straightforward languages, like Python, are strange looking: