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About using rperl

by hakonhagland (Scribe)
on Aug 13, 2019 at 09:13 UTC ( #11104372=perlquestion: print w/replies, xml ) Need Help??

hakonhagland has asked for the wisdom of the Perl Monks concerning the following question:

I just saw this video about RPerl. Maybe I am missing something, but how can this be useful?
  • If I want fast code, I can write it directly in C++, why would I use RPerl?
  • As I understand it, I cannot use CPAN modules with rperl? They first have to be rewritten to comply with the restricted sub set of Perl? It feels like this is a major issue
  • If I find a piece of a large perl program that needs optimization, how can I use rperl to optimize only that part of the code? Do I compile the code first into a shared library, and then load it at run time using DynaLoader? Then, why not just write an XS-module?
Note: I am not trying to criticize the project. I found it very interesting. I am just trying to understand how it can be used in practice. Thanks!

Replies are listed 'Best First'.
Re: About using rperl
by LanX (Sage) on Aug 13, 2019 at 09:41 UTC
    I'm not an expert on rperl, but I think the answer to your third question should be obvious.

    > Then, why not just write an XS-module?

    XS modules are not easy to write. Being able to write high performance code in "pure" Perl should be an advantage.

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

      Yes I agree! It would be great to see an example of how to call a sub in the shared library from regular Perl code.
        It would be great to see an example of how to call a sub in the shared library
        I haven't seen such example of code, but I attended a talk by Will Braswell a few months ago, and asked whether it is feasible, and Will answered that it is possible. So you could have your CPU intensive nested loops or other computations in a RPerl module, and the rest in a regular Perl program. This looks very interesting to me, because it seems easier to write a RPerl module than an XS module.
Re: About using rperl
by dave_the_m (Monsignor) on Aug 13, 2019 at 11:26 UTC
    As far as I can tell, RPerl is perl but with every feature which makes perl either useful or "perlish" removed.


      Yeah, I definitely get your point and I mostly agree. And I probably don't want to write a full RPerl application.

      But if I could write my main program in Perl and have my limited CPU intensive part(s) of the code (e.g. deeply nested loops) in RPerl, maybe I could have the best of two worlds: high speed of compiled programs for the CPU intensive part, and the high expressive power of Perl for the rest of the program.

      I once agree with you, but now I don't. you think RPerl is not real perl, just because rperl is not smart enough yet.

      I don't talk with Will Braswell, But I believe that his target is Rperl will be a compiler for perl which compile all no magic perl code but remain magic perl for perl itself automatically!. That would save a lot of time to manual write C/XS code for performance.

        If RPerl ever starts to be able to seamlessly e.g. mix in regexes, use $1, declare lexical vars without types, become able to use a string var as an integer without an explicit conversion, etc etc, then I will of course revise my opinion of it.


Re: About using rperl
by Anonymous Monk on Aug 14, 2019 at 02:31 UTC

    If I want fast code, I can write it directly in C++, why would I use RPerl?

    Why write directly in C++ when you can write directly in perl? rperl writes the c++ for you

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