use Params::Validate qw( validate_pos validate );
use Contextual::Return;

# and later in the args to validate I could do:
sub fun {
    my $self = shift;
    my $args = validate( @_, { fun => Params::Validate::ARRAYREF } );
    return 
        LIST     { @{ $args{fun} } }
        ARRAYREF { $args{fun} }
        SCALAR   { $#{$args{fun}} }
        DEFAULT  { croak "illegal context" }
}