6 ms·

Adder: Python with a Lisp

53 points by metageek 16y ago

metageek 16y ago
This is the language I presented two years ago at the 2009 International Lisp Conference. It's finally ready for people to try out. From the documentation: Adder is a Lisp-1 which compiles to Python. It aims to integrate seamlessly into Python: every Adder function is a Python function, every Adder list is a Python list, etc. Python-on-Lisp has been tried before; I think Adder has two advantages that previous attempts did not. The first is technical: Python's metaprogramming has gotten better in the past few years, which allows Adder to integrate more smoothly. The second is social: Clojure has prepared the ground for the notion of a Lisp that integrates into an existing language. It has one bit of non-Lispy syntax: foo.bar.baz means exactly what it does in Python, and .bar.baz is a function, defined so that (.bar.baz foo) is identical to foo.bar.baz.
- julian37 16y ago
  Hi, thanks -- this looks great! Does it support tail recursion (in constant space)?
  - metageek 16y ago
    No, because it compiles to Python. I suppose I could finagle some way to manage it for self-calls, by putting the whole function in a loop. Although that would bind the function name earlier than usual for Python. In Python, you can (in theory) do this: def fact(n,sofar): if n<2: return sofar else: return fact(n-1,n*sofar) f=fact fact=lambda n,sofar: 3 ...whereupon f(7,1)==3. I suppose I wouldn't really mind if Adder broke that consistently, but I don't think I like the idea of breaking it only for functions that do self-tail-calls.
    - ckcheng 16y ago
      How about considering Clojure's style of using recur to support self-tail-call optimization using explicit syntax?
      - metageek 16y ago
        Hmm. Maybe. I'd have to look closer. My main resistance is that I've used languages where you have to use special syntax for a recursive function, and I hate it. But this isn't quite the same thing.
      - silentbicycle 16y ago
        Does it really make sense to add a workaround-to-a-workaround?
    - julian37 16y ago
      Have you considered using a "trampoline" function like this? http://paulbutler.org/archives/tail-recursion-in-python/ http://paulbutler.org/archives/tail-recursion-in-python/
      - metageek 16y ago
        Interesting...no, I hadn't seen that before. I'll think about it.
      - silentbicycle 16y ago
        You'll get a lot out of _Lisp in Small Pieces_ (http://pagesperso-systeme.lip6.fr/Christian.Queinnec/WWW/LiSP.html http://pagesperso-systeme.lip6.fr/Christian.Queinnec/WWW/LiS...), as well. Python wouldn't be my first choice, and I'm unconvinced that Lisp-Py makes sense, but I'm sure you'll find ways to adapt it regardless.
    - runningdogx 16y ago
      A flag to enable targeting stackless python instead of normal python?
- rednum 16y ago
  I gave it a quick look and I wonder why would I want to use it? I am a fan of both lisp and python and enjoy trying new languages but why would I want to use it instead of one of those languages? What exactly cool features does it offer?
  - metageek 16y ago
    Well, the main one is that you combine access to Python libraries with Lisp macros.
sedachv 16y ago
In case you're wondering, you can also put your Python in a Lisp: http://common-lisp.net/project/clpython/ http://common-lisp.net/project/clpython/
adamc 16y ago
Interesting. The name isn't the best to google for, though...
- metageek 16y ago
  True. It comes up as #2 and #3 if you google for "adder lisp", though.
apgwoz 16y ago
I have an unreleased/unfinished Scheme to Python interpreter, which is intended to be a full compiler. I'm using trampolining for everything as I wanna be able to support call/cc at some capacity, so there's a factor of slowdown to using it, but it's pretty fun nevertheless.

53 points by metageek 16y ago

This is the language I presented two years ago at the 2009 International Lisp Conference. It's finally ready for people to try out. From the documentation: Adder is a Lisp-1 which compiles to Python. It aims to integrate seamlessly into Python: every Adder function is a Python function, every Adder list is a Python list, etc. Python-on-Lisp has been tried before; I think Adder has two advantages that previous attempts did not. The first is technical: Python's metaprogramming has gotten better in the past few years, which allows Adder to integrate more smoothly. The second is social: Clojure has prepared the ground for the notion of a Lisp that integrates into an existing language. It has one bit of non-Lispy syntax: foo.bar.baz means exactly what it does in Python, and .bar.baz is a function, defined so that (.bar.baz foo) is identical to foo.bar.baz.

julian37 16y ago
Hi, thanks -- this looks great! Does it support tail recursion (in constant space)?
- metageek 16y ago
  No, because it compiles to Python. I suppose I could finagle some way to manage it for self-calls, by putting the whole function in a loop. Although that would bind the function name earlier than usual for Python. In Python, you can (in theory) do this: def fact(n,sofar): if n<2: return sofar else: return fact(n-1,n*sofar) f=fact fact=lambda n,sofar: 3 ...whereupon f(7,1)==3. I suppose I wouldn't really mind if Adder broke that consistently, but I don't think I like the idea of breaking it only for functions that do self-tail-calls.
  - ckcheng 16y ago
    How about considering Clojure's style of using recur to support self-tail-call optimization using explicit syntax?
    - metageek 16y ago
      Hmm. Maybe. I'd have to look closer. My main resistance is that I've used languages where you have to use special syntax for a recursive function, and I hate it. But this isn't quite the same thing.
    - silentbicycle 16y ago
      Does it really make sense to add a workaround-to-a-workaround?
  - julian37 16y ago
    Have you considered using a "trampoline" function like this? http://paulbutler.org/archives/tail-recursion-in-python/ http://paulbutler.org/archives/tail-recursion-in-python/
    - metageek 16y ago
      Interesting...no, I hadn't seen that before. I'll think about it.
    - silentbicycle 16y ago
      You'll get a lot out of _Lisp in Small Pieces_ (http://pagesperso-systeme.lip6.fr/Christian.Queinnec/WWW/LiSP.html http://pagesperso-systeme.lip6.fr/Christian.Queinnec/WWW/LiS...), as well. Python wouldn't be my first choice, and I'm unconvinced that Lisp-Py makes sense, but I'm sure you'll find ways to adapt it regardless.
  - runningdogx 16y ago
    A flag to enable targeting stackless python instead of normal python?
rednum 16y ago
I gave it a quick look and I wonder why would I want to use it? I am a fan of both lisp and python and enjoy trying new languages but why would I want to use it instead of one of those languages? What exactly cool features does it offer?
- metageek 16y ago
  Well, the main one is that you combine access to Python libraries with Lisp macros.

sedachv 16y ago

In case you're wondering, you can also put your Python in a Lisp: http://common-lisp.net/project/clpython/ http://common-lisp.net/project/clpython/

adamc 16y ago

Interesting. The name isn't the best to google for, though...

metageek 16y ago
True. It comes up as #2 and #3 if you google for "adder lisp", though.

apgwoz 16y ago

I have an unreleased/unfinished Scheme to Python interpreter, which is intended to be a full compiler. I'm using trampolining for everything as I wanna be able to support call/cc at some capacity, so there's a factor of slowdown to using it, but it's pretty fun nevertheless.