Re^4: Generating powerset with progressive ordering

[tlm]

A powerset should always include the empty set. (The cardinality of the powerset of a set of cardinality n should be 2ⁿ.) Therefore, you can simplify powerset:

sub powerset {
  my ( $car, @cdr ) = @_;
  my @cdr_powerset = @cdr ? powerset( @cdr ) : [];
  return ( @cdr_powerset, map [ $car, @$_ ], @cdr_powerset );
}

I imagine that this means that only two states are needed in iter_powerset.