An Enum is a record containing common helper functions

Create an Enum from a list of String and variants

type Fruit
    = Apple
    | Banana
    | Mango


fruit : Enum Fruit
fruit =
    Enum.create
        [ ( "Apple", Apple )
        , ( "Banana", Banana )
        , ( "Mango", Mango )
        ]

Create an Enum from an iterator function and a starting variant. It may look unusual, but the benefit is that the case statement helps ensure that you don't forget a variant.

type Fruit
    = Apple
    | Banana
    | Mango


fruit : Enum Fruit
fruit =
    Enum.fromIterator
        (\a ->
            case a of
                Apple ->
                    ( "Banana", Banana )


                Banana ->
                    ( "Mango", Mango )


                Mango ->
                    ( "Apple", Apple )
        )
        Apple

Enums based on Int instead of String

Create an EnumInt from a list of Int and variants

type Fruit
    = Apple
    | Banana
    | Mango


fruit : EnumInt Fruit
fruit =
    Enum.createInt
        [ ( 1, Apple )
        , ( 2, Banana )
        , ( 3, Mango )
        ]

Create an EnumInt from an iterator function and a starting variant

type Fruit
    = Apple
    | Banana
    | Mango


enum : EnumInt Fruit
enum =
    Enum.fromIntIterator
        (\a ->
            case a of
                Mango ->
                    ( 1, Apple )


                Apple ->
                    ( 2, Banana )


                Banana ->
                    ( 3, Mango )
        )
        Apple