use v6-alpha;

use Test;
plan 11;

# L<S03/List infix precedence/the cross operator>
ok eval('<a b> X <c d>'), 'cross non-meta operator parses';

# L<S03/List infix precedence/permutations of its sublists>
is eval('@(<a b> X <1 2>)'), <a 1 a 2 b 1 b 2>,
    'non-meta cross produces expected result';

# L<S03/List infix precedence/This becomes a flat list in>
my @result = gather {
    for @(1..3 X 'a'..'b') -> $n, $a {
	take "$n:$a"
    }
}
is @result, <1:a 1:b 2:a 2:b 3:a 3:b>, 'smooth cross operator works';

# L<S03/List infix precedence/and a list of arrays in>
@result = eval q{{
    gather for @@(1..3 X 'A'..'B') -> $na {
	take $na.join(':');
    }
}};
is @result, <1:A 1:B 2:A 2:B 3:A 3:B>, 'chunky cross operator works';

# L<S03/Cross operators/formed syntactically by placing>
ok eval('<a b> X,X <c d>'), 'cross metaoperator parses', :todo<feature>;

# L<S03/Cross operators/"string concatenating form is">
is eval('<a b> X~X <1 2>'), <a1 a2 b1 b2>,
    'cross-concat produces expected result', :todo<feature>;

# L<S03/Cross operators/desugars to something like>
is eval('[~]«( <a b> X,X <1 2> )'), <a1 a2 b1 b2>,
    'X,X works with hyperconcat', :todo<feature>;

# L<S03/Cross operators/list concatenating form when used like this>
my @result = eval '<a b> X,X 1,2 X,X <x y>';
is @result.elems, 8, 'chained cross-comma produces correct number of elements',
    :todo<feature>;
my @expected = (
    ['a', 1, 'x'],
    ['a', 1, 'y'],
    ['a', 2, 'x'],
    ['a', 2, 'y'],
    ['b', 1, 'x'],
    ['b', 1, 'y'],
    ['b', 2, 'x'],
    ['b', 2, 'y'],
);
is @result, @expected,
    'chained cross-comma produces correct results', :todo<feature>;

# L<S03/Cross operators/any existing non-mutating infix operator>
is eval('(1,2 X*X 3,4)'), (3,4,6,8), 'cross-product works', :todo<feature>;

# L<S03/Cross operators/underlying operator non-associating>
dies_ok '@result XcmpX @expected XcmpX <1 2>',
    'non-associating ops cannot be cross-ops';