Range / tuple enums

[nixpulvis]

I've been thinking about writing a strict type for a deck of cards in rust (for example), and I've found myself really wanting this feature. The idea is to allow ranges or tuples in the definition of an enum. This would allow Rust to express (easily) larger numbers of variants for enums. This would play nicely with enum refinement typing, as I've read about elsewhere.

enum CardValue(0...13);
// Or
enum CardValue(1,2,3,4,5,6,7,8,9,10,11,12,13);

enum Suit {
    Hearts,
    Diamonds,
    Clubs,
    Spades,
}

struct Card {
    value: CardValue,
    suit: Suit,
}
// Or
struct Card {
    value: enum(0...13),
    suit: Suit,
}
// Or
struct Card {
    value: (0...13),
    suit: Suit,
}

[ticki]

I ask: What you're suggesting is type-level ranges? If so, are you proposing ability to do arithmetic operations on them?

[KalitaAlexey]

@nixpulvis How do you want to assign Card.value?

Card.value = 12;

or

Card.value = CardValue::12;

I'd like to write second variant. But I don't know is it possible?

[nixpulvis]

@KalitaAlexey I could see a number of ways possibly. These are the two options that most jump out at me. One treats the created enum very much like enums are treated today, the other required the compiler to know that 1 is somehow a valid value for the enum. I'd be happy with the first option to start, then working toward getting the second option maybe.

enum CardValue(0...13);

struct Card {
    value: CardValue,
    suit: Suit,
}

let card = Card {
    value: CardValue(1),
    suit: Suit::Clubs,
};

// Or

struct Card {
    value: (0...13),
    suit: Suit,
}

let card = Card {
    value: 1,
    suit: Suit::Hearts,
};