Modern Perl

Perl Templating Ecosystems

The old saying goes every Perl programmer designs at least one templating language.  The present author is no exception, having authored a system roughly based on some bits of XSLT I liked.  Eventually you find your way toward one of the more popular existing system, such as Mason (more than just templating, I know), HTML::Template or Template::Toolkit.

After what seemed like years of stagnation, it appears once again that people are growing tired with the available options.  Most of the big three have received what seems to be only minor updates in the 21st century.  On the one hand you could say this means they are complete.  My gut feeling here is that they are not growing due to people not really being able to meaningfully contribute to the projects.  Either the principal author has not gone to pains to encourage this (by prolonged absences or general approachability) or the underlying source code is too idiosyncratic for people to be able to figure out how to join in.

I've noticed this problem in other, core Perl modules. How many very important projects have just one author?  Part of this is due to the highly individualistic and 'do it yourself' attitude of the Perl community.  Are there other reasons?  I'd like to hear your thoughts, particularly if you are someone that maintains a Templating systems on CPAN or someone that contributes or tried to contribute to one. 

Moose Type Constraints

Since I last wrote have been working a lot improving the MooseX::Types library system and cleaning up some related issues in Moose, as well as developing the new MooseX::Types::Structured type constraint library.  First off, MooseX::Types now properly supports parameterized types, so you can:

subtype ArrayRefOfInts,
 as ArrayRef[Int];

and it will work as expected.  Recursive types let's you create something like:

subtype Tree,
 as ArrayRef[Branch];

subtype Branch,
 as ArrayRef[Branch|Leaf];

Which basically means "A Tree is an array reference of one or more Branch(es) and each Branch is an array reference to more Branch(es) or Leaves".  Notice the '|' overloading to support the Union 'Or' type constraint.

I know this is just a taste, more details to come later.  Until then you'll have to make do with the linked documentation and associated test examples.

Happy New Year!