custom-type.elm

type PullRequestState
    = Proposed
    | Rejected
    | Merged

branchColor : PullRequestState -> String
branchColor state =
    case state of
        Proposed ->
            "yellow"

        Rejected ->
            "red"

        Merged ->
            "green"
--------------------------------------------------
type Availability
    = SoldOut
    | InStock Int
    | Reordered ( Int, Int )
    | Announced String


displayStatus : Availability -> String
displayStatus availability =
    case availability of
        SoldOut ->
            "Sold out"

        InStock amount ->
            "In stock: " ++ String.fromInt amount ++ " left."

        Reordered days ->
            let
                min =
                    days
                        |> Tuple.first
                        |> String.fromInt

                max =
                    days
                        |> Tuple.second
                        |> String.fromInt
            in
            "Available again in " ++ min ++ " to " ++ max ++ " days."

        Announced date ->
            "Available on " ++ date ++ "."


foo =
    displayStatus (InStock 42)
-- "In stock: 42 left." : String

bar =
    displayStatus (Reordered ( 3, 5 ))
-- "Available again in 3 to 5 days." : String


baz =
    displayStatus (Announced "2016-12-24")
-- "Available on 2016-12-24." : String


availabilities : List Availability
availabilities =
    [ SoldOut
    , InStock 42
    , Reordered ( 3, 5 )
    ]


bob =
    List.map displayStatus availabilities
-- ["Sold out","In stock: 42 left.","Available again in 3 to 5 days."] : List Str