Having ported 20 Perl 5 CPAN modules to Perl 6 in the last few days, these are some things I noticed:

You can find a perhaps more recent version of this document in the Pugs SVN repository.


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Re: Mini HowTo: How to port Perl 5 modules to Perl 6
by webfiend (Vicar) on Mar 25, 2005 at 20:55 UTC

    Very nicely put together. I had to read this twice, though. Once for the "Aaagh! So many changes. What are they doing to the grep/map chain? How are those accessors better? Waah!" Then once more, a few minutes later, to recognize how much cleaner this will make a lot of my Perl code. Now I'm all excited again!

      The old grep/map/sort chain works unmodified, too, I just wanted to demonstrate the new pipeline operators. Actually, there are even some other ways too:

      # Perl 5: print join "...", map {...} sort {...} @array; # Perl 6: say (@array.sort:{...} ==> map {...}).join("...");

      TIMTOWTDI :)

      The accessors are especially useful for subclassing:

      class Foo { has $.x; # Explicitly generate an accessor: method x() is rw { return new Proxy: FETCH => {...}, STORE => {...}; } } class Foo::Bar isa Foo { method do_sth { ...; my $var = $.x; # Although used as an variable, the *method* Foo.x is called. # Foo::Bar does *not* directly access the variable. } }

      Now, you may ask, "why is that useful?" -- In Perl 5, when one changed the internal representation of some data in the superclass, but fixed the public accessor methods so they translate between the old representation the user expects and the new one used internally, everything was fine. Except, when there was some subclass: The subclass would still directly access the internal representation, which would, of course, not work.

      Now, with Perl 6, one may subclass freely without having to fear that internal changes of the superclass will affect the subclass. :)

      Generally, the Perl 5 way works in Perl 6, too. But the new ways Perl 6 gives you are often shorter/clearer/more consice/more elegant/more efficient/whatever.


Re: Mini HowTo: How to port Perl 5 modules to Perl 6
by crenz (Priest) on Mar 30, 2005 at 09:08 UTC

    Thanks for your effort! I have wanted to try out Pugs, but haven't gotten around doing it so far. Can you quickly outline the process to try out a module after porting it -- will Pugs run the module "out of the box", or will I need to install anything else? That information would help me to go and start porting myself.

      you will need to install GHC and the Perl6-Pugs , Pugs as of now does not have support for classes (this is being built and will be available from ver 6.2x) . hope this helps