Day December 9, 2010

Day 9 – The module ecosystem

ttjjss 2 Comments

The Perl 6 module database on http://modules.perl6.org is certainly not CPAN yet, but there are still a number of things worth using, or at least knowing about. There’s no "standard" module installer for Perl 6, like there’s a cpan shell for Perl 5, but the most commonly used and most often working is neutro. It’s a simple script fetching, building, and installing modules from the ecosystem, resolving dependencies and checking if the tests are passing: not much more we need. Let’s see how to install something interesting with it, say JSON::Tiny, a JSON parser.

First, we need to get neutro. We will assume you use git to obtain it; notice that git is also obligatory to download modules (all of them live on github currently).

    git clone git://github.com/tadzik/neutro.git
    cd neutro
    PERL6LIB=tmplib bin/neutro .

That will download neutro and bootstrap it using the supplied libs. What we end up is the module installer itself, and the File::Tools and Module::Tools distributions. Make sure ~/.perl6/bin is in your PATH enviroment variable, so you will be able to run neutro without specifying its exact location. You are now able to install modules as simply as with cpanminus:

    neutro json
    neutro perl6-Term-ANSIColor
    neutro perl6-lwp-simple

You may notice module names are not similar to what you may be used to from Perl 5. They’re not standarized, they’re just the names of a git repos they live in. To make sure what you are looking for, consult the
list:

    neutro update # fetch the fresh list of modules
    neutro list

Modules will be installed to ~/.perl6/lib, which is in the default search path of Rakudo, so you don’t really need to set PERL6LIB yourself:

    perl6 -e 'use Term::ANSIColor; say colored("Hello blue world!", "blue")'

You probably just can’t wait to write your first module and make it available for the whole world. There’s no CPAN where you can send your packages; the usual workflow is creating a repository on Github and adding it to the projects.list file in the ecosystem. You don’t need to have a direct access to the repo to get your module published. You can either send a pull request for your forked ecosystem repo, send a patch, or just ask some of the commiters or people on the #perl6 channel of Freenode.

How to write a module, what tools to use? If you’re interested, look into the guide.

Happy hacking!