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Python syntax in Lisp and Scheme

I think everyone who used Python will agree that its syntax is
the best thing going for it. It is very readable and easy
for everyone to learn. But, Python does not a have very good
macro capabilities, unfortunately. I'd like to know if it may
be possible to add a powerful macro system to Python, while
keeping its amazing syntax, and if it could be possible to
add Pythonistic syntax to Lisp or Scheme, while keeping all
of the functionality and convenience. If the answer is yes,
would many Python programmers switch to Lisp or Scheme if
they were offered identation-based syntax?
Jul 18 '05
699 34030
This whole thread is a bad idea. If you like python then use python.
Personally I find Scheme and Common Lisp easier to read but that's
just me, I prefer S-exps and there seems to be a rebirth in the Scheme
and Common Lisp communities at the moment. Ironically this seems to
have been helped by python. I learned python then got interested in
it's functional side and ended up learning Scheme and Common Lisp. A
lot of new Scheme and Common Lisp developers I talk to followed the
same route. Python is a great language and I still use it for some
things.

Paul Rubin's comments are just pure fud.

Some great scheme implementations with large modern libraries (not yet
a match for python but growing fast):
http://www.plt-scheme.org/
http://www-sop.inria.fr/mimosa/fp/Bigloo/
http://www.wikipedia.org/wiki/Gauche
http://sisc.sourceforge.net/
http://www.scheme.com/

Common Lisp has a fantastic wiki site (links to implementations and
loads of libraries) with everything you need to get started at:
http://www.cliki.net/index

Also see:
http://www.lisp.org/alu/home
http://common-lisp.net
http://www.cliki.net/YoungLispers

Many of the latest Scheme and Lisp mailing lists can be browsed from:
http://news.gmane.org/index.php?match=gmane.lisp

Develop in the language that suits you but despite the fud you do have
a choice,
Python, Scheme and Common Lisp are all fine languages with good
libraries and FFI capabilities.

Regards,
Mark.

Paul Rubin <http://ph****@NOSPAM.i nvalid> wrote in message news:<7x******* *****@ruckus.br ouhaha.com>...
mi*****@ziplip. com writes:
If the answer is yes, would many Python programmers switch to Lisp
or Scheme if they were offered identation-based syntax?


I don't think the syntax is that big a deal. But programming in lisp
or scheme has a creaky feeling these days, because the traditional
runtime libraries in those languages have fallen so far behind the
times.

Jul 18 '05 #11
ka****@lycos.co m (Mark Brady) writes:
Paul Rubin's comments are just pure fud. [...] Develop in the language that suits you but despite the fud you do have
a choice,
Python, Scheme and Common Lisp are all fine languages with good
libraries and FFI capabilities.


I think that's incorrect: The Common Lisp language has no FFI (foreign
function call) capabilities. Each CL _implementation _ has one (which
is usually compatible to itself). This is exactly the reason why
there are way more libraries out there for Python, Perl, maybe Ruby
than for any single CL implementation. The same probably holds for
Scheme.
Jul 18 '05 #12
ka****@lycos.co m (Mark Brady) writes:
just me, I prefer S-exps and there seems to be a rebirth in the Scheme
and Common Lisp communities at the moment. Ironically this seems to
have been helped by python. I learned python then got interested in
it's functional side and ended up learning Scheme and Common Lisp.


It's be interesting to know where people got the idea of learning
Scheme/LISP from (apart from compulsory university courses)? I think
that for me, it was the LPC language used in LPmuds. It had a
frightening feature called lambda closures, and useful functions such
as map and filter. Then one day I just decided to bite the bullet and
find out where the heck all that stuff came from (my background was
strongly in C-like languages at that point. LPC is like C with some
object-oriented and some FP features.)

Yes, I know, there's nothing frightening in lambda closures. But the
way they were implemented in LPC (actually just the syntax) was
terrible :)
Jul 18 '05 #13
mi*****@ziplip. com wrote:
I think everyone who used Python will agree that its syntax is
the best thing going for it. It is very readable and easy
for everyone to learn. But, Python does not a have very good
macro capabilities, unfortunately. I'd like to know if it may
be possible to add a powerful macro system to Python, while
keeping its amazing syntax, and if it could be possible to
You can surely hack a "pre-processor" on top of the Python
interpreter. With the Python 2.3 architecture of import
hooks, it might even be quite feasible to experiment with
this idea as a pure Python package and distribute it as such:
just add a hook that scans incoming source files (modules)
for definitions and/or occurrences of the 'macros' you want,
and (respectively) squirrels away the definitions, and/or
expands the macros. As for designing the syntax for macro
definitions and expansions while remaining 'amazing', I'll
pass -- but surely it's not beyond human possibilities;-).

Anyway, see later in this post for a toy-level example.

add Pythonistic syntax to Lisp or Scheme, while keeping all
of the functionality and convenience. If the answer is yes,
would many Python programmers switch to Lisp or Scheme if
they were offered identation-based syntax?


If you could make all of the existing Python extensions,
libraries, frameworks, etc, instantly available from Lisp or
Scheme, you'd gain a LOT of kudos in the Lisp or Scheme
community, I suspect. That most existing Python coders
would be happy to leave the semantic simplicity of their
chosen language for the richness of Common Lisp, I very,
very strongly doubt, but in any case until the whole array
of existing extensions &c is available it's not an issue;-).
So, anyway, here's the promised toy-level example of using
custom importers with the new Python 2.3 mechanics to get
macros. I'm cutting corners to the bone (just to mix a
couple metaphors...) by using the C preprocessor (!) as my
"macro expander", ignoring packages, _and_ only looking for
"C-macro" definitions AND expansions in files with extension
".pyp" (all others, I'll leave alone...). Oh, also, I do
not worry about saving bytecode for such files -- I'm gonna
preprocess and recompile them on every run of the program
(far too much trouble, when macros exist, to determine
whether a bytecode file is up to date -- one should check
it, not only with respect to the date of ONE source file,
but rather of a hard-to-pin-down collection of macro and
include files... so, in the spirit of cutting corners and
keeping this a VERY toy-level example, I'm punting:-). So,
here's the gist...:
import sys
import os
import imp

prepro = 'cat %s | gcc -E -'

class MacroImporter(o bject):

def __init__(self, path):
self.path = path

def find_module(sel f, modname):
look_for_file = os.path.join(se lf.path, modname+'.pyp')
self.code = os.popen(prepro % look_for_file). read()
if self.code: return self
else: return None

def load_module(sel f, modname):
mod = imp.new_module( modname)
sys.modules[modname] = mod
mod.__file__ = "<Macro-Expanded %s>" % modname
exec self.code in mod.__dict__
return mod

sys.path_hooks. append(MacroImp orter)

example = open('pippo.pyp ', 'w')
example.write(' ''
#define unless(cond) if not(cond)
def pippo(x):
print 'x is', x
unless(x>=2): print ' x is smaller than two'
unless(x<=4): print ' x is bigger than four'
''')
example.close()

import pippo
pippo.pippo(1)
pippo.pippo(7)
Removing the various oversimplificat ions, and, in particular, designing
a better macro scheme than gcc -E supplies, is left as a trivial exercise
for the reader (I have in fact devised a perfect scheme, of course, but,
unfortunately, the margins of this post are too narrow for me to write it
down...).
Alex

Jul 18 '05 #14
On 03 Oct 2003 14:44:36 +0300, Toni Nikkanen wrote:
ka****@lycos.co m (Mark Brady) writes:
just me, I prefer S-exps and there seems to be a rebirth in the Scheme
and Common Lisp communities at the moment. Ironically this seems to
have been helped by python. I learned python then got interested in
it's functional side and ended up learning Scheme and Common Lisp.
It's be interesting to know where people got the idea of learning
Scheme/LISP from (apart from compulsory university courses)?


Try http://alu.cliki.net/The%20Road%20To%20Lisp%20Survey

--
Cogito ergo I'm right and you're wrong. -- Blair Houghton

(setq reply-to
(concatenate 'string "Paul Foley " "<mycroft" '(#\@) "actrix.gen.nz> "))
Jul 18 '05 #15


Toni Nikkanen wrote:
ka****@lycos.co m (Mark Brady) writes:

just me, I prefer S-exps and there seems to be a rebirth in the Scheme
and Common Lisp communities at the moment. Ironically this seems to
have been helped by python. I learned python then got interested in
it's functional side and ended up learning Scheme and Common Lisp.

It's be interesting to know where people got the idea of learning
Scheme/LISP from (apart from compulsory university courses)?


<g> We wonder alike. That's why I started:

http://alu.cliki.net/The%20Road%20to%20Lisp%20Survey

That recently got repotted from another cliki and it's a little mangled,
but until after ILC2003 I am a little too swamped to clean it up. But
there is still a lot of good stuff in there. On this page I grouped
folks according to different routes to Lisp (in the broadest sense of
that term): http://alu.cliki.net/The%20RtLS%20by%20Road

You will find some old-timers because I made the survey super-inclusive,
but my real interest was the same as yours: where are the New Lispniks
coming from?

Speaking of which, Mark Brady cited Python as a stepping-stone, and I
have been thinking that might happen, but the survey has yet to confirm.
Here's one: http://alu.cliki.net/Robbie%20Sedgew ick's%20Road%20 to%20Lisp

So Ping! Mark Brady, please hie ye (and all the others who followed the
same road to Lisp) to the survey and correct the record.

I think that for me, it was the LPC language used in LPmuds. It had a
frightening feature called lambda closures, and useful functions such
as map and filter. Then one day I just decided to bite the bullet and
find out where the heck all that stuff came from (my background was
strongly in C-like languages at that point. LPC is like C with some
object-oriented and some FP features.)

Yes, I know, there's nothing frightening in lambda closures. But the
way they were implemented in LPC (actually just the syntax) was
terrible :)


You could cut and paste that into the survey as well. :)

kenny

Jul 18 '05 #16

"Mark Brady" <ka****@lycos.c om> wrote in message
news:e8******** *************** ***@posting.goo gle.com...
This whole thread is a bad idea.
I could agree that the OP's suggestion is a bad idea but do you
actually think that discussion and more publicity here for Lisp/Scheme
is bad? You make a pretty good pitch below for more Python=>Lisp
converts.
If you like python then use python.
As I plan to do.
Personally I find Scheme and Common Lisp easier to read but that's
just me, I prefer S-exps and there seems to be a rebirth in the cheme and Common Lisp communities at the moment. Ironically this seems to
have been helped by python. I learned python then got interested in
it's functional side and ended up learning Scheme and Common Lisp. A
lot of new Scheme and Common Lisp developers I talk to followed the
same route. Python is a great language and I still use it for some
things.


Other Lispers posting here have gone to pains to state that Scheme is
not a dialect of Lisp but a separate Lisp-like language. Could you
give a short listing of the current main differences (S vs. CL)? If I
were to decide to expand my knowledge be exploring the current
versions of one(I've read the original SICP and LISP books), on what
basis might I make a choice?

Terry J. Reedy

Jul 18 '05 #17
Kenny Tilton <kt*****@nyc.rr .com> writes:
Speaking of which, Mark Brady cited Python as a stepping-stone, and I
have been thinking that might happen, but the survey has yet to
confirm.


It usually happens that when I google for some scheme/lisp-isms,
I get lots of Python mailing list messages as results. There's
something going on with that.
Jul 18 '05 #18


Kenny Tilton wrote:


Toni Nikkanen wrote:
It's be interesting to know where people got the idea of learning
Scheme/LISP from (apart from compulsory university courses)?

<g> We wonder alike. That's why I started:

http://alu.cliki.net/The%20Road%20to%20Lisp%20Survey

That recently got repotted from another cliki and it's a little mangled,
but until after ILC2003 I am a little too swamped to clean it up.


Me and my big mouth. Now that I have adevrtised the survey far and wide,
and revisited it and seen up close the storm damage, sh*t, there goes
the morning. :) Well, I needed a break from RoboCells:

http://sourceforge.net/projects/robocells/

I am going to do what I can to fix up at least the road categorization,
and a quick glance revealed some great new entries, two that belong in
my Top Ten (with apologies to those getting bumped).

kenny

Jul 18 '05 #19
Paul Rubin <http://ph****@NOSPAM.i nvalid> wrote in message news:<7x******* *****@ruckus.br ouhaha.com>...
mi*****@ziplip. com writes:
If the answer is yes, would many Python programmers switch to Lisp
or Scheme if they were offered identation-based syntax?


I don't think the syntax is that big a deal. But programming in lisp
or scheme has a creaky feeling these days, because the traditional
runtime libraries in those languages have fallen so far behind the
times.


Funny. Yesterday i downloaded the trial version of Franz Lisp (Allegro
CL).
I can'T say if the runtime libraries are out of date because there is
absolute no documentation for the runtime libraries - of course they
also bundle the ANSI-Common Lisp book.

I found that they still want to sell every fucking line of code in an
extra library raising the price to an unexceptable high value.
Jul 18 '05 #20

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