Is python not good enough?

David Cournapeau cournape at
Sun Jan 17 02:19:01 CET 2010

On Sun, Jan 17, 2010 at 4:17 AM, John Nagle <nagle at> wrote:
> Nobody wrote:
>> On Fri, 15 Jan 2010 12:34:17 -0800, John Nagle wrote:
>>>    Actually, no.  It's quite possible to make a Python implementation
>>> that
>>> runs fast.  It's just that CPython, a naive interpreter, is too primitive
>>> to do it.  I was really hoping that Google would put somebody good at
>>> compilers in charge of Python and bring it up to production speed.
>>>    Look at Shed Skin, a hard-code compiler for Python
>> A hard-code compiler for the subset of Python which can easily be
>> compiled.
>> Shed Skin has so many restrictions that it isn't really accurate to
>> describe the language which it supports as "Python".
>> Hardly any real-world Python code can be compiled with Shed Skin. Some of
>> it could be changed without too much effort, although most of that is the
>> kind of code which wouldn't look any different if it was implemented in
>> C++ or Java.
>> The monomorphism restriction is likely to be particularly onerous: the
>> type of a variable must be known at compile time; instances of subclasses
>> are allowed, but you can only call methods which are defined in the
>> compile-time class.
>> If you're writing code which makes extensive use of Python's dynamicity,
>> making it work with Shed Skin would require as much effort as re-writing
>> it in e.g. Java, and would largely defeat the point of using Python in the
>> first place.
>> If you want a language to have comparable performance to C++ or Java, you
>> have to allow some things to be fixed at compile-time. There's a reason
>> why C++ and Java support both virtual and non-virtual ("final") methods.
>    My point is that Python is a good language held back by a bad
> implementation.  Python has gotten further with a declaration-free syntax
> than any other language.  BASIC and JavaScript started out declaration-free,
> and declarations had to be retrofitted.  Python has survived without them.
> (Yes, there are hokey extensions like Psyco declarations and "decorators",
> but both are marginal concepts.)

There are efficient implementations of dynamic programming languages
which do not rely on declaration (if by declaration you mean typing
declaration), even when available:

See also:


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