I would not consider SPITBOL esoteric since it was not intended as such — but the original INTERCAL-72 interpreter was written in SPITBOL, so the language is quite important to esolang history (and deeply weird, besides).

Mostly because JS is so widely-used and so encourages others to expand or contribute to the language. And partly because JS is delightfully chaotic, so it feels right for esolang work. But I might make a different choice with my next interpreter…

Yes, you build a command in pieces, breaking it down so as not to seem too petty to the gods in any single line of code. The longer the request, the more praise must be given, but also you can’t repeat yourself too much (if you call Ariadne “mistress of the labyrinth” the first time, the second time you might instead call her “wise and cunning one whose agile mind finds purchase on the frailest of notions.” The project is here: https://github.com/rottytooth/Olympus and here’s an introduction: https://www.youtube.com/watch?v=Agq99SyHfFw

Also, while Forth may not be esoteric, there’s always Chuck Moore’s other creation, colorForth. https://colorforth.github.io/

Hi, I’m the author of the book and arriving (a bit late) to clarify a few things.

Although I discuss esolang history in the Spectrum piece (something I get deeper into on my blog, https://esoteric.codes), the book is a monograph of my esolangs specifically: Folders, Entropy, Olympus and more; some are collected at https://danieltemkin.com/Esolangs. It’s meant to make esolangs approachable, focusing on concept rather than technical aspects of the languages. I wrote it to encourage people to experiment with esolangs and to show the community-based nature of the work: the delightful conversation that happens when another programmer takes your language in a direction you would never have conceived of.

The languages range from fully implemented works to pieces that are not implementable (e.g. Past Tense is a language whose programs are not runnable by definition and would cease to be programs if they were https://github.com/rottytooth/PastTense). There’s one where even articulating a program into words or symbols invalidates it: only unreified thought is valid.

The languages are presented first as prompts. In the second half, I present details on those that are implemented, showing the sometimes surprising results of carrying out the initial idea. I hope it will expand the conversation around esoteric languages as an art form.