TODO: Insert the description of changes. Also, mention that Rakudo 2012.12 (Warszawa) was released and that Rakudo isn’t Rakudo Star.
$_ variable is used, Rakudo assumes block. This could break your code if you were expecting a hash.my $a; { $a; my $a } is an error.for runs in sink (void) or list context, just like map (actually, for does exactly what map does). If you were depending on it, you can use eager do before for to force eager execution.X::Comp::Group exception. It’s used when compilation can produce multiple issues.my ($a, $a); only causes warnings, not fatal errors.X::Undeclared::Symbols exception for variables that weren’t declared, but used..message on Exceptions..perl output for a Pair that has key that is a Pair.X::Item is thrown for @a[NaN] or @a[Inf]. It isn’t incompatible change because it wasn’t working before anyway.