In RaceSeq§

See primary documentation in context for method serial

multi method serial(RaceSeq:D:)

Converts the object to a Seq and returns it.

In HyperSeq§

See primary documentation in context for method serial

multi method serial(HyperSeq:D:)

Converts the object to a Seq and returns it.

In Any§

See primary documentation in context for method serial

multi method serial()

This method is Rakudo specific, and is not included in the Raku spec.

The method returns the self-reference to the instance itself:

my $b;                 # defaults to Any 
say $b.serial.^name;   # OUTPUT: «Any␤» 
say $b.^name;          # OUTPUT: «Any␤» 
my $breakfast = 'food';
$breakfast.serial.say; # OUTPUT: «food␤» 

This is apparently a no-op, as exemplified by the third example above. However, in HyperSeqs and RaceSeqs it returns a serialized Seq, so it can be considered the opposite of the hyper/race methods. As such, it ensures that we are in serial list-processing mode, as opposed to the autothreading mode of those methods.