Python 3.0 and language evolution

Question

Python 3.0 breaks backwards compatibility with previous versions and splits the language into two paths (at least temporarily). Do you know of any other language that went through such a major design phase while in maturity?

Also, do you believe that this is how programming languages should evolve or is the price to pay simply too high?

Answer 1

The only language I can think of to attempt such a mid-stream change would be Perl. Of course, Python is beating Perl to that particular finish line by releasing first. It should be noted, however, that Perl's changes are much more extensive than Python's and likely will be harder to detangle.

(There's a price for Perl's "There's More Than One Way To Do It" philosophy.)

There are examples like the changes from version to version of .NET-based languages (ironic, considering the whole point of .NET was supposed to be API stability and cross-platform compatibility). However, I would hardly call those languages "mature"; it's always been more of a design-on-the-go, build-the-plane-as-we-fly approach to things.

Or, as I tend to think of it, most languages come from either "organic growth" or "engineered construction." Perl is the perfect example of organic growth; it started as a fancy text processing tool ala awk/sed and grew into a full language.

Python, on the other hand, is much more engineered. Spend a bit of time wandering around the extensive whitepapers on their website to see the extensive debate that goes into every even minor change to the language's syntax and implementation.

The idea of making these sorts of far-reaching changes is somewhat new to programming languages because programming languages themselves have changed in nature. It used to be that programming methodologies changed only when a new processor came out that had a new instruction set. The early languages tended to either be so low-level and married to assembly language (e.g. C) or so utterly dynamic in nature (Forth, Lisp) that such a mid-stream change wouldn't even come up as a consideration.

As to whether or not the changes are good ones, I'm not sure. I tend to have faith in the people guiding Python's development, however; the changes in the language thus far have been largely for the better.

I think in the days to come the Global Interpreter Lock will prove more central than syntax changes. Though the new multiprocessor library might alleviate most of that.