File Coverage

blib/lib/Data/Monad/Maybe.pm

Criterion	Covered	Total	%
statement	32	32	100.0
branch	6	6	100.0
condition			n/a
subroutine	13	13	100.0
pod	7	7	100.0
total	58	58	100.0

package Data::Monad::Maybe;
use strict;
use warnings;
use parent qw/Data::Monad::Base::MonadZero/;
use Carp ();
use Scalar::Util qw/reftype/;
use Exporter qw/import/;

our @EXPORT = qw/just nothing/;

sub just { bless [@_], __PACKAGE__ }
sub nothing() { bless \(my $d = undef), __PACKAGE__ }

sub unit {
    my $class = shift;
    just @_;
}

sub zero {
    my $class = shift;
    nothing;
}

sub flat_map {
    my ($self, $f) = @_;
    $self->is_nothing ? $self : $f->($self->value);
}

sub is_nothing { reftype $_[0] ne 'ARRAY' }

sub value {
    my ($self) = @_;
    if ($self->is_nothing) {
        Carp::carp "nothing has no values";
        ();
    } else {
        wantarray ? @$self : $self->[0];
    }
}

1;

__END__