If you ever wondered how to write a programming language, this is probably the best resource to get started (and then of course Crafting Interpreters).
I've always found MAL ("Make-A-Lisp" https://github.com/kanaka/mal) a bit more approachable, probably because I was out after creating my own programming language before I've written much Python. It's language agnostic, and really easy to follow along with most programming languages out there, explaining everything as you progress.
That it's language agnostic and somehow matters feels weird now a lot of time (and experience I suppose) afterwards, but back when I only knew 1-2 languages by heart, also having to face understanding Python at the same time from Norvigs guide/reference made it slightly more complicated for me.
I use this as a litmus test now when coming across new languages (implementing MAL in the new language), as it's such an easy approach to practically test large parts of the new language, and there is always host-language-specific tricks you can learn along the way.
There are edge cases where this fails, but `def parse(s): return json.loads('['+re.sub('([")])\s*(["(])','\g<1>,\g<2>',re.sub('[^()\s]+','"\g<0>"',s)).replace('(','[').replace(')',']')+']')` is a surprisingly robust lisp parser.
It's funny, in the 8-bit days a lot of us learned programming for its own sake without much expectation it'd be lucrative. Took ~50 years to get back to that spirit as the default.
I actually perfected the Norvig Lisp at one time. It has compiler to python and just everything. Those very few here that can actually read code, understand why this project soon exploded into biggest piece of odorous excrement.
My Lisp from 1975 was actually used in real world and highly lucrative. Gemini could read the source code, but it told that my code was piece of shit and cannot be implemented in 64-bit world without drastic changes, so it made an example. But that version was just too advanced and too complex as a study subject. There are already enuff good Lisps in the world, methinks.
Interestingly enough, linguists also use Lisp-like parentheses or brackets to annotate sentence structures. Trees and brackets are isomorphic, as both phrase structure grammarians and the original SICP lectures pointed out.
The brackets in the title sentence would look a lot different though. ;-)
I've been working on a similar (ish) project for a while: Ribbit (https://github.com/udem-dlteam/ribbit). Supports a full R4RS REPL (with tail-calls) in the same sizes as Lispy (8Kb for JavaScript and 6.5Kb for x86)!
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[ 2.8 ms ] story [ 41.9 ms ] threadIlluminating experience and it will also help you see (among many other things) the parentheses in a different light.
See also part 2 https://norvig.com/lispy2.html
That it's language agnostic and somehow matters feels weird now a lot of time (and experience I suppose) afterwards, but back when I only knew 1-2 languages by heart, also having to face understanding Python at the same time from Norvigs guide/reference made it slightly more complicated for me.
I use this as a litmus test now when coming across new languages (implementing MAL in the new language), as it's such an easy approach to practically test large parts of the new language, and there is always host-language-specific tricks you can learn along the way.
https://www.codesections.com/blog/raku-lisp-impression/
https://github.com/timonoko/nokolis.py
Related:
(How to Write a (Lisp) Interpreter (In Python)) (2010) - https://news.ycombinator.com/item?id=39665939 - March 2024 (91 comments)
(How to Write a (Lisp) Interpreter (In Python)) (2010) - https://news.ycombinator.com/item?id=30443949 - Feb 2022 (9 comments)
(How to Write a (Lisp) Interpreter (In Python)) - https://news.ycombinator.com/item?id=30327437 - Feb 2022 (3 comments)
(How to Write a (Lisp) Interpreter (In Python)) - https://news.ycombinator.com/item?id=26036431 - Feb 2021 (1 comment)
How to Write a Lisp Interpreter In Python (2010) - https://news.ycombinator.com/item?id=20590439 - Aug 2019 (29 comments)
How to Write a Lisp Interpreter in Python (2010) - https://news.ycombinator.com/item?id=12777852 - Oct 2016 (28 comments)
How to Write a Lisp Interpreter in Python (2010) - https://news.ycombinator.com/item?id=7825054 - May 2014 (41 comments)
(How to Write a ((Better) Lisp) Interpreter (in Python)) - https://news.ycombinator.com/item?id=1746916 - Oct 2010 (10 comments)
(How to Write a (Lisp) Interpreter (in Python)) - https://news.ycombinator.com/item?id=1745322 - Sept 2010 (39 comments)
https://github.com/timonoko/nokolisp
The brackets in the title sentence would look a lot different though. ;-)
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https://wmedrano.dev/post/2025/11/15/lisp-1
Writing a LISP in Python is only for educational use, or to have a boostrap LISP that you can write a better (faster) LISP in.