Python syntax in Lisp and Scheme

[Alex Martelli]

Daniel P. M. Silva wrote:
   ...
>>> with_directory("/tmp", do_something())
   ...
>> Right: you need to code this very differently, namely:
>>     with_directory("/tmp", do_something)
   ...
>> The only annoyance here is that there is no good 'literal' form for
>> a code block (Python's lambda is too puny to count as such), so you
   ...
> That was my point.  You have to pass a callable object to with_directory,
> plus you have to save in that object any variables you might want to use,
> when you'd rather say:
> 
> x = 7
> with_directory("/tmp",
>         print "well, now I'm in ", os.getpwd()
>         print "x: ", x
>         x = 3
>         )

I'm definitely NOT sure I'd "rather" use this specific syntax to pass
a block of code to with_directory (even in Ruby, I would delimit the
block of code, e.g. with do/end).

I *AM* sure I would INTENSELY HATE not knowing whether

   foo('bar', baz())

is being evaluated by normal strict rules -- calling baz and passing
the result as foo's second argument -- or rather a special form in
which the 'baz()' is "a block of code" which foo may execute zero or
more times in special ways -- depending on how foo happens to be
bound at this time.  *SHUDDER*.  Been there, done that, will NEVER
again use a language with such ambiguities if I can possibly help it.


>> the details.  Consensus is culturally important, even though in the end
>> Guido decides: we are keen to ensure we all keep using the same language,
>> rather than ever fragmenting it into incompatible dialects.
> 
> The point is that the language spec itself is changed (along with the
> interpreter in C!) to add that statement.  I would be happier if I could
> write syntax extensions myself, in Python, and if those extensions worked
> on CPython, Jython, Python.Net, Spy, etc.

So, I hope the cultural difference is sharply clear.  To us, consensus
is culturally important, we are keen to ensure we all keep using the
same language; *you* would be happier if you could use a language that
is different from those of others, thanks to syntax extensions you
write yourself.  Since I consider programming to be mainly a group
activity, and the ability to flow smoothly between several groups to
be quite an important one, I'm hardly likely to appreciate the divergence
in dialects encouraged by such possibilities, am I?


> I think changing the meaning of __new__ is a pretty big language
> modification...

Surely you're jesting?  Defining a class's __new__ and __init__
just means defining the class's *constructor*, to use the term
popular in C++ or Java; as I can change any other method, so I
can change the constructor, of course (classes being mutable
objects -- by design, please note, not by happenstance).  "Pretty
big language modification" MY FOOT, with all due respect...


Alex