// simple array/list:

.multiunit {

@v: abc "abc" 1 1px 1% #123;
length: length(@v);
extract: extract(@v, 1) extract(@v, 2) extract(@v, 3) extract(@v, 4) extract(@v, 5) extract(@v, 6);

}

.incorrect-index {

@v1: a  b  c;
@v2: a, b, c;
v1: extract(@v1,  5);
v2: extract(@v2, -2);

}

.scalar {

@var:          variable;
var-value:     extract(@var, 1);
var-length:    length(@var);
ill-index:     extract(@var, 2);

name-value:    extract(name, 1);
string-value:  extract("string", 1);
number-value:  extract(12345678, 1);
color-value:   extract(blue, 1);
rgba-value:    extract(rgba(80, 160, 240, 0.67), 1);
empty-value:   extract(~'', 1);

name-length:   length(name);
string-length: length("string");
number-length: length(12345678);
color-length:  length(blue);
rgba-length:   length(rgba(80, 160, 240, 0.67));
empty-length:  length(~'');

}

.mixin-arguments {

.mixin-args(a b c d);
.mixin-args(a, b, c, d);
.mixin-args(1; 2; 3; 4);

}

.mixin-args(@value) {

&-1 {
    length:  length(@value);
    extract: extract(@value, 3) ~"|" extract(@value, 2) ~"|" extract(@value, 1);
}

}

.mixin-args(…) {

&-2 {
    length:  length(@arguments);
    extract: extract(@arguments, 3) ~"|" extract(@arguments, 2) ~"|" extract(@arguments, 1);
}

}

.mixin-args(@values…) {

&-3 {
    length:  length(@values);
    extract: extract(@values, 3) ~"|" extract(@values, 2) ~"|" extract(@values, 1);
}

}

.mixin-args(@head, @tail…) {

&-4 {
    length:  length(@tail);
    extract: extract(@tail, 2) ~"|" extract(@tail, 1);
}

}

// “multidimensional” array/list

.md-space-comma {

@v: a b c, 1 2 3, "x" "y" "z";
length-1:  length(@v);
extract-1: extract(@v, 2);
length-2:  length(extract(@v, 2));
extract-2: extract(extract(@v, 2), 2);

&-as-args {.mixin-args(a b c, 1 2 3, "x" "y" "z")}

}

.md-cat-space-comma {

@a: a b c;
@b: 1 2 3;
@c: "x" "y" "z";
@v: @a, @b, @c;
length-1:  length(@v);
extract-1: extract(@v, 2);
length-2:  length(extract(@v, 2));
extract-2: extract(extract(@v, 2), 2);

&-as-args {.mixin-args(@a, @b, @c)}

}

.md-cat-comma-space {

@a: a, b, c;
@b: 1, 2, 3;
@c: "x", "y", "z";
@v: @a @b @c;
length-1:  length(@v);
extract-1: extract(@v, 2);
length-2:  length(extract(@v, 2));
extract-2: extract(extract(@v, 2), 2);

&-as-args {.mixin-args(@a @b @c)}

}

.md-3D {

@a: a b c d, 1 2 3 4;
@b: 5 6 7 8, e f g h;
.3D(@a, @b);

.3D(...) {

    @v1:       @arguments;
    length-1:  length(@v1);
    extract-1: extract(@v1, 1);

    @v2:       extract(@v1, 2);
    length-2:  length(@v2);
    extract-2: extract(@v2, 1);

    @v3:       extract(@v2, 1);
    length-3:  length(@v3);
    extract-3: extract(@v3, 3);

    @v4:       extract(@v3, 4);
    length-4:  length(@v4);
    extract-4: extract(@v4, 1);
}

}