Python vs Ruby

[Alex Martelli]

Amol Vaidya <mynewsa at gmail.com> wrote:

> Hi. I am interested in learning a new programming language, and have been
> debating whether to learn Ruby or Python. How do these compare and contrast
> with one another, and what advantages does one language provide over the
> other? I would like to consider as many opinions as I can on this matter
> before I start studying either language in depth. Any help/comments are
> greatly appreciated. Thanks in advance for your help. 

Within the panorama of existing languages, Python and Ruby are just
about as similar as two languages independently developed are likely to
get (and then some -- there is clearly some minor mutual influence, e.g.
Ruby probably picked 'def' for function definition partly-because that's
what Python uses, and later Python may have picked 'yield' for
generators partly-because that's what Ruby uses to have a method
interact with a block it gets passed).  They address the same niches and
share most of the same strengths (and minor weaknesses).

Pragmatically, Python is more mature -- with all sort of consequences,
e.g., Python will be faster for many tasks (more time has been spent on
optimizing it), more third-party libraries and tools are available, etc,
but the Python community may be less easy to "get into" than the newer,
smaller Ruby one, for example.

Here's a tiny script showing some similarities and differences:

def f()
  i = 0
  while i < 1000000
    j = 923567 + i
    i += 1
  end
end

f()

comment out the 'end' statements, and at colons at the end of the def
and while statements, and this is also valid Python.  On my iBook...:

Helen:~ alex$ time ruby -w tim.rb 

real    0m5.367s
user    0m5.129s
sys     0m0.041s

while:

Helen:~ alex$ time python tim.py

real    0m1.078s
user    0m0.953s
sys     0m0.063s

Note that this is NOT the normal way to loop in either language, so do
NOT read too much into the reported times -- a 5:1 ratio is NOT normally
observed on real tasks, though it IS reasonably normal for Python to be
somewhat faster.  BTW, this is Python 2.4.1 and Ruby 1.8.2.

I'm pretty sure that the Ruby community at some point will go through
much the same exercise the Python one did in the several years spent on
the transitions 2.2 -> 2.3 -> 2.4 -- reduce the amount of change in the
language and library and focus most development effort on optimization
instead.  I know of no intrinsic reason why Ruby and Python should not
deliver just about equal performance for similar tasks, though the
current implementations may not be equivalent (yet) from this POV.

Python in recent years moved to enhance its object model (making it in
some ways closer to Ruby) and iteration abilities (ditto), while Ruby
moved to shed more and more of its Perl legacy (though in both cases
legacy issues may have slowed down progress a little bit, yet for both
languages the direction is clear).  This makes the two languages more
similar and to some extent interchangeable.

Ruby has acquired a framework ("Ruby on Rails") that makes it very
desirable to implement database-backed web sites; while Python's running
hot after it (e.g. with Django), for this specific task Rails is better
today (e.g., you can get good _books_ about Rails, but not yet about
Django).  "Ruby Gems" is a good package management system that is fully
operational today; again, Python's catching up, but it's not there yet.

For other things, Python's existing base of third-party extensions and
tools is above Ruby's.  For example, Numeric (and numarray and scipy,
etc) make Python excellent for heavy-duty number crunching, and I do not
know of Ruby equivalents in this area; Twisted is a great framework for
asynchronous network programming, and, again, it's a Python advantage;
and so on, and so forth.  However, there is a downside: for some tasks
(e.g., web-site frameworks) Python has _too many_ good 3rd party
extensions available, making it hard to choose among them!

We can proceed to compare the languages themselves.  Many differences
are minor and cosmetic.  Typically, Python is more specific, giving you
fewer cosmetic choices: e.g., you must use parentheses in defining and
calling functions, while, in Ruby, parentheses are optional (though
often recommended) for these same tasks.  Ruby's approach of having
everything be an object on the same plane, infinitely modifiable until
and unless explicitly frozen, is more regular, while Python's approach
of giving slightly special status to built-in types and making them not
modifiable dynamically is slightly less regular but may be more
pragmatic.  OTOH, Python's approach to "callable objects" (essentially
making them all fully interchangeable) is the more regular of the two.
Ruby's approach to iteration (passing the code block into a method) is
essentially equivalent to Python's (iterators and generators), with
several minor advantages and disadvantages on either side.  One could go
on for quite a long time, but to some extent these are all minor
quibbles, nothing really earth-shaking in the mix.  Writing Ruby
extensions in C is slightly easier (thanks to mark-and-sweep garbage
collecton, mostly), but Python offers many alternatives (e.g., pyrex)...

Personally, I'm happy to stick with Python, but I keep studying Ruby
when new books &c about it come out (I'm biased, having written Python
books, but the Ruby books from the "pragmatic programmers" are also
quite good ones, no two ways about it).  I think that if you try both
and consider accurately all the uses you may want to put them to, you'll
most probably be happy with either... or both!


Alex