compare to lists to find matches

_in.less

@import 'for';

// compare two lists
// the wild animals will show a picture and a warning "This animal is wild"
// others do not


@wild: bear, tiger, elefant, lion, zebra, crocodile, gorilla;
@animals: gorilla, dog, cat, hamster, tiger;

.in(@array, @value) {
    .for(@array); .-each(...) {}
    .-each(~'@{value}') {@-: true}
    .-() {@-: false} .-;
}

.wild(@bool) when (@bool) {
    &:before {
        content: url('../images/@{i}.png');
    }
    &:after {
        content: 'This animal is wild.'
    }

}

.animal {
    .for(@animals);.-each(@i){
        .in(@wild, @i);
        &.@{i} {
            .wild(@-);

        }
    }
}

// output
//.animal.gorilla:before {
//  content: url('../images/gorilla.png');
//}
//.animal.gorilla:after {
//  content: 'This animal is wild.';
//}
//.animal.tiger:before {
//  content: url('../images/tiger.png');
//}
//.animal.tiger:after {
//  content: 'This animal is wild.';
//}
// example: http://codepen.io/pixelass/pen/Ggkwy