I'm going to have speak subjectively and relative to my own skills here. Without rigorous use of standards Perl 5 is a nightmare to read. With very clear and consistent style then it can be readable, but this has to be enforced extremely strictly for any code base beyond trivial. Perl's 100 ways to do things is not a positive in this context.
Case in point, I was given a bit of perl two weeks ago by a bioinformatics lecturer. Did not use strict or warnings; variables weren't declared in scope; no subroutines, let alone Moose objects. And this is typical of ~90% of bioinformatics perl that gets written. What's more, it was a trivial script that was simply parsing some BLAST matches from CSV, checking for overlaps and assigning a type based on the match gene combination - and was completely indecipherable. It took me two days of refactoring to pick out all the details. And he managed to use a couple of magic symbols I'd never seen before.
The first time I was given a bit of python, without learning the language at all, I was able to extend the script and get it do some new things (it was considerably more complex than the aforementioned perl script).
And even when it is well written and documented - I did work with some very good perl programmers - it's tended to end up as very fragile and difficult to extend or even substantially redevelop due to the heavy use of context for determining behaviour (and the actual context can be difficult to determine). Unit testing had to be very extensive since it was difficult to isolate changes.
I'm going to have to be precise here - I'm attacking Perl 5. It just seemed from that section that Perl 6 doesn't solve the major problem (difficult to deduce the context and work out the resulting effect) I had with Perl 5. I may be completely missing the mark and actually readability is much better. I really hope so.
>> Perl 6 isn't production ready yet. But even a cursory glance over the features tells, Python isn't even in the same league of tools Perl 6 will be.
Vapourware is vapourware. Perl 6 was meant to be production ready a decade ago. On the other hand, I'm interested in knowing what you think Perl 6 brings that will give it the edge over Python? Do you see it displacing Python as rapidly as Python replaced Perl 5 as the science "glue" language of choice? With the apparent rise of Julia as well, could it just be too late?