Announcing P6lert: Perl 6 Alerts Directly From Core Developers

2017-12-29 | 869 words | Info about P6lert service

Development of Rakudo Perl 6 is quite fast-paced, with hundreds of commits made each month to its five core repositories. Users undoubtedly feel some impact from those commits: bug fixes may break code that relied on them, backend changes may have unforeseen impact on the user code, new useful features may be implemented that users would want to know about.

In the past, for things with very large impact, we made blog posts, but there are lots of small things that fly under the radar, unless you actively pay a lot of attention to Rakudo Perl 6's core development.

To help all of our users to be aware of important issues, we're announcing introduction of P6lert service: tweet-sized alerts from Perl 6 Core Developers.

The Goods

The P6lert service primarily consists of website, but with it come a variety of ways to receive alerts posted on it:

The Content

While we'll make adjustments as we move forward, I foresee most of the non-critical alerts will largely include things that are: (a) more important than simply hoping users-who-care will read about it in the ChangeLog; (b) not as important to warrant a notification blog post.

As a rule-of-thumb, if you picture a user who added p6lert script to their compiler upgrade procedure, the alerts the script will show will inform that user on everything they need to know to perform that upgrade safely.

The alerts are also deliberately length-limited to be easy to process and fast to digest. As they're posted via an IRC bot, the poster has at most about 400 characters to work with.

Each alert has an affects field for it, giving additional info what the alert applies to. I think it'll often be empty, as alerts affecting latest compiler versions imply they affect whatever latest release is at the time alert was posted.

The alerts have a severity rating: low, normal, and high indicating how important an alert is. Along with those, come two out-of-band ratings: info and critical. Info alerts will usually be something the users don't need to act upon, while critical alerts will often simply contain a link to a blog post that details a critical issue.

Of the top of my head, here are some real-life examples from the past and how I'd rate their severity on the P6lert service:

  • info - Telemetry implementation. This was a fairly large implementation of a feature in the core and some users may be interested in it. At the same time, they don't have to act on this alert. Rakudo and Rakudo Star release may also be info alert material.
  • low - implementation of output buffering on IO handles. Once that was implemented, we noticed some minor fallout in code that assumed lack of buffering. A low-severity alert could notify users about this.
  • normal - A real-life normal-severity alert is already posted on the site. During 6.d spec pre-release review, the Str.parse-names method was placed under deprecation and its functionality was moved to live under Str.uniparse. While this method always existed as a 6.d-proposal, it's known to us that some users already use it and an alert will help them ensure their code keeps working past 6.e language release.
  • high - a while ago, .subst was briefly made to die if it couldn't write to $/; same as some methods already do. Upon examination of ecosystem fallout, this change was reverted, pending further review. However, were it to stay, a high-severity alert would be in order.
  • critical - when we finished work on lexical require, conditional loading of modules many users used was silently failing and the users needed to change their code to correct reliance on the old, buggy behavour. We issued a blog post with upgrade instructions. A critical alert would be a link to this blog post.

That's my vision for host the system will be used, but it'll evolve to suit our needs as more core devs and more of our users start using it. The core dev docs for the system along with code for all the pieces is available in perl6/alerts repo.


As part of improving using user experience, Perl 6 core devs now offer service that will list important information about latest developments in the land of Perl 6. There are numerous ways to consume those alerts, such as an RSS or Tweeter feeds, a command line utility, and an easy-to-use API.

The alerts will come in 5 different severity ratings, indicating their importance. We'll continue to improve the system to best suit our users' needs.

If you have any questions or feedback, you can always talk to the core devs on #perl6-dev IRC chat.