use const_exhaustive::Exhaustive;

// there is 1 value of `()`
assert_eq!([()], <()>::ALL.as_slice());

// there are 2 values of `bool`
assert_eq!([false, true], bool::ALL.as_slice());

// works on types with generics
assert_eq!(
    [None, Some(false), Some(true)],
    Option::<bool>::ALL.as_slice()
);

// write your own exhaustive types
#[derive(Debug, Clone, Copy, PartialEq, Exhaustive)]
enum Direction {
    North,
    South,
    East,
    West,
}

assert_eq!(
    [
        Direction::North,
        Direction::South,
        Direction::East,
        Direction::West,
    ],
    Direction::ALL.as_slice()
);

// works on arbitrarily complex types
#[derive(Debug, Clone, Copy, PartialEq, Exhaustive)]
enum Complex {
    Direction(Direction),
    More {
        foo: Option<bool>,
        bar: (Result<Direction, [bool; 4]>),
    },
}

// works with generics*
#[derive(Debug, Clone, Copy, PartialEq, Exhaustive)]
struct Wrapper<T>(T);

#[derive(Debug, Clone, Copy, PartialEq, Exhaustive)]
struct DirectionSet<T> {
    pub north: T,
    pub south: T,
    pub east: T,
    pub west: T,
}

#[derive(Debug, Clone, Copy, PartialEq, Exhaustive)]
enum ForDirection<T> {
    North(T),
    South(T),
    East(T),
    West(T)
}