A Lisp in 99LOC | Hacker News Reader

A Lisp in 99LOC

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108 pointsshikaan26 comments

Holy cow this is —structurally, not just expression— some of the worst C code I have ever seen, with the abuse of the 'double' type, 'T' cast that looks like a declaration, endian dependency, and strict aliasing violations galore… does this even work on a modern compiler? o.O

It does not, because there is a syntax error on line 81 (extra close parenthesis):

https://github.com/Robert-van-Engelen/tinylisp/blob/2d0fb35b...

Brought to you by this marvellous commit with the message "update",

https://github.com/Robert-van-Engelen/tinylisp/commit/40c6c0...

Yeah. It's munged to fit in 99 lines.

That's besides my point, which is why I said "structure, not just expression".

It could've used a struct rather than wedging tags into a double's first byte and still be 99 lines.

If that's the trick you object to then you will be sad to hear that Ruby uses it.

That's a standard technique in interpreters. All non-toy Javascript engines use it, for example.

Nan-boxing is awesome.

Surpringly readable though, despite all that, if you've ever implanted a language in similar constraints.

*implemented.

Too late to edit now.

Certainly not the worst I have seen, by far; but yes, not pretty. IMHO “Just for making it shorter“. I would very much prefer 200 lines of actually readable nice code.

For reading, I enjoyed fe, which was very clear: https://news.ycombinator.com/item?id=36239175

Yes! Exactly what I meant. 700 lines, but of code that can be understood, and looks clearly as C. Also btw, the general file structure, the documentation, I prefer fe any day of the week. Thanks for pointing that out, I will take a look at it.

Previously:

* https://news.ycombinator.com/item?id=32100035

* https://news.ycombinator.com/item?id=32095655

and

* https://BI6.US/CO/N/20250420.HTML#/042402

Lisp in ~100 lines of Python:

https://flownet.com/ron/l.py

Or from the venerable: https://norvig.com/lispy.html

Can’t you just “import lisp”?

Um, no?

    Python 3.11.6 (v3.11.6:8b6ee5ba3b, Oct  2 2023, 11:18:21) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import lisp
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ModuleNotFoundError: No module named 'lisp'

A better starting point:

https://github.com/Robert-van-Engelen/tinylisp/blob/main/tin...

It's interesting that he seems to have written this for a pocket computer, because there actually was a pocket computer of similar vintage that had LISP built in -- 1989's Casio AI-1000

https://pockemul.com/index.php/2020/04/27/pockemul-1-10-0-ne...

>C code in this project is strongly Lisp-like in compact form

Kinda reminds me J-flavored Whitney's one-page J interpreter.

The commented longer program listing was fun to read.

can it execute the y-combinator?

It doesn't appear to, but you could always add this to the included common.lisp file:

  (define Y (lambda (f) (lambda args ((f (Y f)) . args))))

I’m pretty sure does not handle TCO… so probably not, unless with a huge stack.

See tinylisp-extras.c for TCO.

https://github.com/Robert-van-Engelen/tinylisp/blob/2d0fb35b...

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