sub context_in_position {
    my ($position_name) = @_;
    
    my $wa = wantarray;
    my $context;
    if    ( $wa )         { $context = 'list'   }
    elsif ( defined $wa ) { $context = 'scalar' }
    else                  { $context = 'void'   }
    
    print "context in position '$position_name': $context\n";
    
    return;
}

sub list { return ( context_in_position( 'a' ),
                    context_in_position( 'b' ), ); }
print "list() in void:\n";
list();
print "list() in scalar:\n";
scalar list();
print "list() in list:\n";
() = list();
__END__
list() in void:
context in position 'a': void
context in position 'b': void
list() in scalar:
context in position 'a': scalar
context in position 'b': scalar
list() in list:
context in position 'a': list
context in position 'b': list