TODO.S05

(This document summarizes features documented in S05 but not in Niecza.
All line numbers are relative to c4882a67.  Also, deliberate discrepencies.)

DUBIOUS: this feature is a possible fossil or otherwise makes no sense
  relative to my current understanding of Perl 6.  Needs discussion,
  maybe removal.
DISCUSS: feature seems sane but there is disagreement over what it is
  or how it needs to work.
GRAPHEME: feature requires NFG string semantics, or interacts strongly
  with NFC/NFD issues.
LOL: feature requires slice context mappings.

(  49) Tiebreaker #5: I still don't know what this means.  (2609 conflicts)
       DISCUSS
( 113) Unicode defines a 'Word' to include all Pc as well. DISCUSS
( 219) Loose matches are mostly not implemented. GRAPHEME
( 226) Also no :samecase, :sameaccent, :samespace. GRAPHEME
( 346) Need to audit whitespace removal algorithm.
( 360) No :sigspace<rule>.
( 396) No ms// or ss///; "mm" is parsed
( 408) No Unicode levels GRAPHEME
( 427) No :Perl5 DISCUSS
( 497) No :ex/:ov LOL
( 535) No :rw
( 768) No internal smartmatches
( 924) $/ is a Cursor inside closures
( 933) Don't know how fail is supposed to work there DISCUSS
( 978) No negative quantifiers DUBIOUS
(1057) No special handling of zero-width matches DISCUSS
(1172) No auto-declared temporary variables $x = <.ident>
(1178) No bindings to existing variables
(1186) No || @array temporal-alternation syntax DISCUSS
(1276) Declarativeness of constants is excessively general
(1461) DISCUSS: STD parses EXPR in assertion:variable, why?
(1585) <[ z..a ]> not treated as compile error DISCUSS
(1679) No <.>
(1718) No <?same>, <?at($pos)>
(1733) <?after> is incomplete DISCUSS
(1744) No <*...> DISCUSS
(1804) No <~~> DISCUSS
(1843) No <|g> etc
(1893) No <ww> or <wb>
(2246) regex :ratchet syntax doesn't work DISCUSS
(2342) ::> is defined in terms of brackets, not temporal alternation
(2380) No <commit> or <cut>
(2460) $foo ~~ rule { } does not automatically dual-anchor (DISCUSS)
(2501) No <prior> (probable fossil) DUBIOUS
(2738) No success value; failed matches return Match
(2910) No concept of cursor directionality DUBIOUS
(3144) Missing captures don't produce Nil DISCUSS
(3718) $0=<.alpha>+ is processed backwards; $0=[<.alpha>]+ is fine
(3750) No array aliasing
(3923) No hash aliasing
(3972) No external aliasing
(3996) No support for multiple Matches LOL
(4160) CORE does not contain STD, parsefile, unbalanced DISCUSS
(4204) No 'augment slang' functionality
(4218) No default-control pragmata
(4237) No transliterations
(4445) No matching against buffers and compact arrays
(4466) No matching against non-stringy positionals
(4496) This seems to contradict (1436)
(4522) I don't know if this should be a special case or just use Str