Whitecoin

# Literal Type

  • Literal Type is an enumerated type. You can use multiple strings, numbers, Boolean values, or nil literals as each item of the enumerated type. When assigning a value to an enumerated type, you must use a compatible enumerated type or enumeration. The literal value in the type, otherwise an error is reported during compilation.

  • The type of the enumeration type at runtime is consistent with the type of the specific value at runtime, that is, the enumeration type is a compile-time type, and there is no enumeration type at runtime

  • The enumeration type has no constructor, which is different from the record type

  • grammar

    type EnumTypeName = LiteralValue1 | LiteralValue2 ...

    LiteralValue1 can use LiteralString | LiteralNumber | LiteralInteger | LiteralBool | nil any of these literals
  • E.g:
    type Gender = "male" | "female" 
    var gender: Gender
    gender = "male" -- Correct
    gender = "Chinese" -- Error: Compile Error

    function a1(p: true)
    end

    function a2(p: 'Chinese')
    end

    let a3: string = gender -- Variables of enumerated type can be explicitly downgraded to the type of enumerated value

    -- Literal Type can also be stitched
    type Cat = "whiteCat" | "blackCat"
    type Dog = "husky" | "corgi"
    type Pets = Cat | Dog
    -- Equivalent to type Pets = "whiteCat" | "blackCat" | "husky" | "corgi"

    type Falsy = "" | 0 | false | nil

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