jnthn/nope.md Secret

## nope.md

      
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    Things that won't make it into 6.christmas
The design docs are full of good things that we simply can't get done in the next couple of
months, and that are simply not worth delaying 6.christmas for. This is an initial attempt
to list some things we're going to explicitly put off for a future Perl 6.
Macros, slangs, and the COMPILING pseudo-package
We have a fairly good idea of where we want to go with these, and what needs doing to get
there. Getting there will need a good amount of compiler engineering work, with some quite
substantial refactors to a few bits of the internals (and avoiding that will likely lead to
a whole bunch of "interesting" inconsistencies). We just don't have the resources to do that
ahead of Christmas. And, while macros and slangs will be great, they're hardly a blocker for
getting lots of useful stuff done in the language.
Jagged arrays
We'll support both fixed-size and multi-dimensional arrays in 6.christmas:
my @weekdays[52;7];
my num @a[3;3;3] @intensity;

But making certain dimensions have an unlimited number of elements is deferred.
User-defined indexing
See S09 for the details, but this is deferred.
The PDL bits of S09
We'll certainly provide multi-dimensional arrays (that work is nearly completed), but
the various other bits mentioned in S09 should be explored in module space first. If
the results lead us to wanting to add to the core language, than can happen in the
future.
The Each type and auto-sorted hashes
Details in S09, if you're curious.
Non-parameter cases of coercion types and definedness types
We'll only support coercion types in signatures:
sub foo(Int() $x) { }

But that's all. Not on variables, not as generic arguments, and so forth. Same
goes for definedness types (the :D and :U type modifiers).
goto
Read the design docs to understand why it's non-trivial, but there's all kinds
of fun (like being able to jump into any zero-arg block, provided all on the way
is also zero arg). We already support labelled loops, and have a rich set of
control flow structures. I suspect more people will learn we didn't do goto by
reading this post than by actually wanting it and finding it missing, anyway.
Missing regex features
Basically, don't expect anything that isn't in Rakudo already to be there in
6.christmas. (Given what's there is enough to parse Perl 6 itself, that's
hardly a disappointing feature set!)
Regexes on things other than Str
Buf and Uni support for regexes is desirable, but we won't get there in time
for 6.christmas.
The interaction of temp and wrap
I'm not sure this will survive in the design anyway, but it certainly won't
make it for 6.christmas. Details in S06.
Auto-loading through CANDO
See S10 for details. It turns out that the FALLBACK method in objects covers
enough interesting use cases for us not to worry too much about this bit of
S10.
The oo pragma
S12 speculates about things like:
use oo :closed :final;

We won't be doing anything about this in 6.christmas, and we'll see about beyond
that. If it's interesting for semantic reasons, it stands a chance of making it
into a future version of the Perl 6 language. If it was just there for performance
reasons, we need to know it will actually help (because dynamic optimization that
knows how to de-optimize can get plenty of the benefits without such a declaration).
Cat
The lazy/infinite string type for stream matching. Will be valuable, but only
really after we wire it into the grammar engine.
Parametric Complex
For 6.christmas, the Complex type will always be a pair of native nums. Being
able to type-parameterize it is conjectured in the design docs, and can be
provided in a future Perl 6.
Sub-byte numeric types
int1, uint1, int2, uint2, int4, and uint4, along with their aliases (like bit),
will not be provided in 6.christmas.
Taint mode
Speculated about in the design docs, but will almost certainly need design
work. May, in a post-slang/macro world, be better handled in module space.
Either way, given taint mode's low use in Perl 5, this isn't going to really
be a significant blocker.