Suspending Rakudo support for Parrot

gistfile1.txt

This past weekend at FOSDEM 2015, Larry announced that there will likely 
be a Perl 6 release candidate in 2015, possibly around the September 
timeframe.  What we're aiming for is concurrent publication of a 
language specification that has been implemented and tested in at 
least one usable compilation environment -- i.e., Rakudo Perl 6.

So, for the rest of 2015, we can expect the Rakudo development team 
to be highly focused on doing only those things needed to prepare for 
the Perl 6 release later in the year.  And, from previous planning and 
discussion, we know that there are three major areas that need work prior 
to release: the Great List Refactor (GLR), Native Shaped Arrays (NSA), 
and Normalization Form Grapheme (NFG).

...which brings us to Parrot.  Each of the above items is made 
significantly more complicated by Rakudo's ongoing support for Parrot, 
either because Parrot lacks key features needed for implementation (NSA, NFG) 
or because a lot of special-case code is being used to maintain adequate
performance (lists and GLR).

Beyond this, at present we don't have any developers on hand that seem
eager to tackle these problems for Parrot, nor do we seem to have a high
demand for Parrot support in our userbase.  Most people seem to have
switched over to using MoarVM as the backend, for many reasons.

In order to better focus our limited resources on the tasks needed for a 
Perl 6 language release later in the year, we're expecting to suspend 
Rakudo's support for the Parrot backend sometime shortly after the 
2015.02 release.

Unfortunately the changes that need to be made, especially for the GLR, 
make it impractical to simply leave existing Parrot support in place 
and have it continue to work at a "degraded" level.  Many of the 
underlying assumptions will be changing.  It will instead be more 
effective to (re)build the new systems without Parrot support and 
then re-establish Parrot as if it is a new backend VM for Rakudo, 
following the techniques that were used to create JVM, MoarVM, and 
other backends for Rakudo.

NQP will continue to support Parrot as before; none of the Rakudo 
refactorings require any changes to NQP.

If there are people that want to work on refactoring Rakudo's support 
for Parrot so that it's more consistent with the other VMs, we can 
certainly point them in the right direction.  For the GLR this will 
mainly consists of migrating parrot-specific code from Rakudo into 
NQP's APIs.  For the NSA and NFG work, it will involve developing a 
lot of new code and feature capabilities that Parrot doesn't possess.