Perl ABC

Perl is highly compatible with all language cores, standard modules, and CPAN modules

Perl's extremely high stability also contributes to standard modules and CPAN modules created by third parties.

Perl language core backwards compatibility

The Perl language core is extremely backwards compatible, and changes that break backwards compatibility are rare. The policy is that the Perl language will evolve while maintaining compatibility.

This makes Perl a very suitable scripting language for places where long-term stability is required, such as scripting for work.

In the real world, automated exams cannot be written in every part, so it is a great benefit to have compatibility when upgrading languages.

The idea of Ruby is that by breaking compatibility, the language gets better and better, which contributes to future profits. Perl, on the other hand, is a language that seeks to maintain compatibility, as breaking the compatibility of programs used in many places can have a significant impact.

I think Python is a language that has an idea between Perl and Ruby that we want to maintain compatibility in minor version upgrades of the language and allow us to break compatibility in major version upgrades.

Perl6 is now positioned as a sister language to Perl and is no longer the successor to Perl. Perl 6 is positioned as another language that is very similar to Perl, between the Perl community and the Perl 6 community. This is different in Perl from the relationship between Python 3 and Python 2.

Perl standard module backward compatibility

The backward compatibility of Perl standard modules is very high. I've never heard of a standard module breaking backwards compatibility.

Therefore, it is very stable and you can use it with confidence.

It can happen from time to time that a module disappears from the standard module. In the shift of the times, there are modules that are judged to be unnecessary to manage as standard modules in the democratic decision of the Perl core team.

However, this does not mean that it will be backwards compatible, but that the module will continue to be available on CPAN.

If you use that module, you have to pay a little for the effort of installing it from CPAN. API changes are unlikely to happen.

Backwards compatibility with CPAN modules

Perl has a mechanism called CPAN that allows you to freely use modules created by a third party. Anyone can create a CPAN module, so it's the module author who is responsible for the backwards compatibility policy for that module.

However, I don't think there are many CPAN authors who have a policy of breaking backwards compatibility. Backward compatibility is not guaranteed at the time of the first experimental release, but most authors will not change the API after this release unless there is a big reason.

The backward compatibility of the CPAN module is generally stable. Most modules are available for Perl 5.8 or Perl 5.10 and above.

One of the hallmarks of the Perl language is that the entire Perl ecosystem of the Perl language core, standard modules, and CPAN modules is extremely stable.