Re^2: What Perl CAN'T do?

[grinder]

perl cannot be written in Perl

Yes it can. There is nothing from stopping you writing a bootstrap parser and eventually creating a self-compiling Perl parser+runtime written in Perl. But, and this is the 2**16 dollar question.... why would you want to do a thing like that?

(For those following along at home who can make no sense of this dialog, the language is Perl, and the interpreter that interprets said language is perl).

One thing I do know... Perl should not be used when speed is of the essence. I'm currently stress testing Regexp::Assemble. I started the run last Friday afternoon on a hexaprocessor box. The run has performed about 147 million combinations as of right now (more than 4.6 billion unit tests), a grand 7% of the problem space...

On the plus side, the run hasn't turned up any bugs.

[tirwhan]

There is nothing from stopping you...

Here are a few things that would hold me back:

1. It would be hard to find others who also want to work on such a project (cause, as you say, 'why?')
2. With a minuscule team of programmers my development speed will likely be slower than that of the mainstream C perl, therefore I'm writing towards a target that's moving further away all the time.
3. Even if I try to write towards a fixed and existing version of perl5 I'll likely not be finished in my lifetime (and if I do nothing but hack on Perlperl all day my lifetime will be even more finite that it is anyway)

You're right, there's nothing in the design of Perl that makes this task impossible in theory, but I'd be willing to bet all the money I own that it is impossible in practice. (Note to prospective punters: it's not very much money :-)

[demerphq]

Thats an interesting comment. Why are you running 4.6 billion unit tests? What behaviour are you testing that requires so many tests? (Note that you are doing about 4.6 billion more tests than perl itself does when testing the regex engine during a build.)