Does it work?

I'll start with a narrow view of your "Does it work?" question:

• The linked code works in the Perl 6 compiler I'm using. (By "linked code" I mean the code in the links I provided, and the red-black tree on Rosetta Code that Moritz linked to.)

• The compiler I'm using is Rakudo on MoarVM. (Rakudo is nowadays the de facto reference Perl 6 compiler and MoarVM the de facto reference Rakudo backend.)

• I set up my Rakudo on MoarVM using the "Rakudobrew" tool. Running `perl6 -v` displays "This is perl6 version 2014.12-117-g2542c3d built on MoarVM version 2014.12-4-g7e95c05". (To duplicate my setup or download any version of Rakudo/NQP/MoarVM use Rakudobrew.)

A look at 'roast', the suite of tests for a Perl 6 compiler, provides part of a broader view of the "does it work?" question:

• To start subjectively assessing test coverage for a feature, first search the design documents to find pages that look relevant, then individually search each such page to find verbiage that seems relevant. Then look for nearby test file links embedded inline within the design doc.

  (Collectively the design docs contain links to most of the 35K+ tests in 'roast'. The rest are for covering things like the 140+ articles in the Perl 6 Advent Calendars; these now have close to 100% coverage thanks to David Warring's determination to sort them out in the latter half of 2014.)

  For example, the design doc section I linked as Unpacking array parameters embeds links to a couple test files from roast: S06-signature/unpack-array.t and S06-multi/unpackability.t.

• To assess test results, look at a recent 'roast', decide which tests are important (eg search for the term(s) relevant to your feature of interest and/or the names of test files of interest) and then focus mainly on any of these tests that failed or are tagged "todo" or "skip".

  For example, searching for "signature" ("pattern matching" doesn't match anything) in the current latest 'roast' run for Rakudo on MoarVM reveals 80+ matches. At the time of writing this I consider just 36 to be of real interest.

  (I ignored matches such as todo tests for the "signature" method on the not-yet-implemented compiler object representing the distro used to compile the compiler.)

  An informal analysis of the matches of interest to me indicated around 500 relevant passing tests and 65 todo/skipped. About half of the latter look like they really need to be done by 6.0, i.e. supposedly by the end of this year, especially the ones covering binding of return values and named arguments. YMMV.

I plan to properly address your "is it worth it?" speed question in a separate comment this weekend.