Comments on: The Tiniest Lisp (in Python)

By: SinC — The Tiniest LISP Compiler (to Python) « Turning air to gold

SinC — The Tiniest LISP Compiler (to Python) « Turning air to gold — Sat, 28 Nov 2009 21:34:45 +0000

[...] by Bernhard Tim Lopez published an elegant and tiny LISP interpreter for Python on his blog. Inspired by Norvig’s Paradigms [...]

By: tim

tim — Sat, 13 Jun 2009 04:07:24 +0000

@Justin: Have you considered Clojure? http://elhumidor.blogspot.com/2009/04/clojure-on-google-appengine.html

By: Justin Goldberg

Justin Goldberg — Fri, 12 Jun 2009 15:20:21 +0000

It would be cool to get Lisp running on Google Appengine (which only supports python and java is in beta).

By: sys

sys — Wed, 30 Jul 2008 22:55:08 +0000

Nice exercise :) you didn’t have to do much work because Python is so close to Lisp. Still, writing Lisp in Lisp beats Python any day for clarity and purity.

By: tim

tim — Fri, 22 Feb 2008 06:46:49 +0000

@Stefano: sent you mail, but it bounced — my e-mail is in the sidebar.

By: stefano rossi

stefano rossi — Fri, 22 Feb 2008 00:33:20 +0000

It’s working now, I can show you some interesting code, how can I send you an email?

By: tim

tim — Thu, 21 Feb 2008 20:23:42 +0000

@Stefano: You want something like (apply (lambda (x) 10) ’20), right? There’s a small bug in apply — it should eval the first arg — and you’ll also need to define lambda as a function. I’m posting a follow up to this article that goes into more detail and also links to other Python/Lisp implementations, as it turns out this is territory that is well trodden.

By: stefano rossi

stefano rossi — Thu, 21 Feb 2008 17:36:23 +0000

Working a lot on this code! But what's wrong with this?: globs["apply"] = lambda sexpr, context: Apply(sexpr[0], sexpr[1], context) print Eval(["apply", ["quote", ["lambda", [], 1]], ["quote", [10]]], globs)

By: Freudness

Freudness — Thu, 21 Feb 2008 05:02:55 +0000

You’re missing a few things, notably a _read function that accepts s-expressions and turns them into list structure. With that, you can do this for a main loop:

while 1:
print _eval(_read())

Note, you’re confusingly using the variable name “sexpr” to refer to lists. An s-expression is a string; it’s comparable to repr() of a list in Python. The s-expression “(1 2)” is equivalent to the Python repr output “[1, 2]“.

By: Eduardo

Eduardo — Thu, 21 Feb 2008 00:52:02 +0000

As someone who bounces between Python and Scheme a lot, I can only say Schweeeeeet!

By: pozorvlak

pozorvlak — Thu, 21 Feb 2008 00:01:22 +0000

Dude. I once wrote a (not terribly good) 150-line Lisp interpreter in Perl, which was until now the shortest Lisp interpreter of which I was aware.

I take my hat off to you.

[Though mine had an actual parsing stage :-) ]

By: tim

tim — Wed, 20 Feb 2008 22:42:55 +0000

“macro” indicates a function that lazy-evaluates the arguments — that is, they are inherently quoted. The type(name) == dict is so that I could use native Python types, although, admittedly, I probably won’t take it that far.

By: stefano rossi

stefano rossi — Wed, 20 Feb 2008 21:19:33 +0000

What’s the purpose and usage of ‘macro’? What’s the purpose of type(name)==dict ?

By: Aaron Brown

Aaron Brown — Wed, 20 Feb 2008 18:18:09 +0000

There are a bunch of “smart” (non-ASCII) quotes in there.

By: Larry Clapp

Larry Clapp — Wed, 20 Feb 2008 17:09:40 +0000

Wow, Lisp is slow! ;)

(Actually, probably the ease of doing exactly what you’ve done contributes quite a bit to this myth. :)

By: buccia

buccia — Wed, 20 Feb 2008 15:43:58 +0000

Impressive.

By: John Connors

John Connors — Wed, 20 Feb 2008 15:33:43 +0000

Would be interesting to try this with boost::lambda and the STL and see how it compares.

By: Steve

Steve — Wed, 20 Feb 2008 14:35:53 +0000

Very cool. Have you seen yvfc.py? Also, can I suggest you getting rid of Wordpress's silly 'texturize' feature? The fancy quotes it inserts into the page makes the code unusable. See here.

By: Clint

Clint — Wed, 20 Feb 2008 14:30:38 +0000

Did that speed it up?

By: tim

tim — Wed, 20 Feb 2008 08:57:39 +0000

Doh! Thanks.