Advance Notice of Significant Changes


Advance Notice of Significant Changes

As part of the IO grant run by The Perl Foundation, we're improving our IO-related methods and subroutines. We've identified several of the changes that will have moderate impact on the users and may require you to update your code.

The exact changes to be made will be known by March 18th, 2017 and the implementation will be part of the 2017.04 Rakudo compiler release on April, 15th, which will be followed by the 2017.04 Rakudo Star Perl 6 release.


Why Are We Changing Stuff?

Our contract with the users is we don't change anything that's covered by the Perl 6.c language version tests. This means most of the language remains reliably stable, but IO features got short-changed on the love. The tests for them are sparse—a big reason why the IO grant is running in the first place—which gives core developers a lot of freedom to change them and to improve them.

Despite that freedom, we realize broken code isn't a nice thing, and will attempt to reduce the impact of the changes, by providing backwards compatible interface to support old API, where feasible. Where not, we will provide information of the upcoming changes; this notice is a part of that effort.

What's Changing?

The grant covers all of IO routines and methods (excluding sockets). All of the final changes are yet to be deliberated and ratified and we'll share the details once they're known.

Currently, it is speculated that link() routine will change the order of arguments (no backwards compatible support will be provided) and seek() routine will take seek reference as a named argument instead of an enum value (backwards compatible support will be provided).

It's very likely many more changes will be made. We'll be using the code of all the modules in the ecosystem to judge the potential impact of the change and evaluate each change on a case-by-case basis.


  • March 18, 2017: finalized information on the changes will be known to the Core Team. Upgrade instructions for users will follow shortly after.
  • April 15, 2017: all of the changes will be completed and 2017.04 compiler release will be made. Rakudo Star Perl 6 distribution will be created from this release in the following week or two.

Help and More Info

If you need help or more information, please join our IRC channel and ask there. You can also contact the person performing this work via Twitter @zoffix (Zoffix on IRC in #perl6-dev)