Where Raku++ excels
Places where Raku++ accepts and runs code the reference implementation does not — constructs Rakudo rejects at compile time or leaves unimplemented. Every example below runs live in your browser.
Shaped arrays @a[i;j]
Indexing a shaped array with fewer subscripts than it has dimensions takes a partial view — here, a whole row. Raku++ returns it. Rakudo compiles the same code but throws at runtime ("Partially dimensioned views of shaped arrays not yet implemented. Sorry."), so this is a Raku++ extension.
my @a[2;3] = (1,2,3),(4,5,6); say @a[1]; # Raku++: [4 5 6] · Rakudo: not yet implemented
The official suite tests exactly this and Rakudo fudges it out — in S09-multidim/indexing.t:
#?rakudo todo "partially dimensioned NYI"
lives-ok { @arr[*;0] }, 'Partially dimensioned view lives';The #?rakudo todo directive marks a test Rakudo itself cannot yet pass. Raku++ runs it — @arr[*;0] returns the column view.
Conjunction & capture aliases
The @<name>=(…) array alias has a hash-valued sibling, %<name>=(…), which collects each matched substring as a key (reached through $<name>). Rakudo reserves %-sigil variables in regex syntax and rejects the construct at compile time ("The use of hash variables in regexes is reserved"), so this one is Raku++-only.
if "a1b2c3" ~~ / [ %<seen>=(<:L>) \d ]+ / {
say $<seen>.keys.sort; # Raku++: (a b c) · Rakudo: won't compile
}
The official suite has a whole 116-test file for hash aliases — S05-capture/hash.t (spec reference L<S05/Hash aliasing>):
ok(" a b\tc" ~~ m/%<chars>=( \s+ \S+ )/, 'Named unrepeated hash capture');
ok($/<chars>{' a'}:exists, 'One key captured');Current Rakudo no longer compiles the %<…>=(…) syntax ("The use of hash variables in regexes is reserved"), so it cannot run that file at all. Raku++ does.