GenderDecoder.elm

genderDecoder : Decoder Gender
genderDecoder =
    [ maleDecoder
    , femaleDecoder
    ]
        |> Decode.oneOf

maleDecoder : Decoder Gender
maleDcoder =
    eyeColorDecoder
        |> Decode.field "eyeColor"
        |> Decode.map


eyeColorDecoder : Decoder EyeColor
eyeColorDecoder =
    Decode.string
        |> toEyeColorDecoder


toEyeColorDecoder : String -> Decoder EyeColor
toEyeColorDecoder str =
    case str of
        "blue" ->
            Decode.succeed Blue

        _ ->
            Decode.fail "Eye color not a recognized color"