2011-07-25 Extending types in F#

2011-07-25 extending-types-in-fsharp

# Title: 
# Author: Mikael Lundin
# Link: http://blog.mikaellundin.name/2011/07/25/extending-types-in-fsharp.html

hand.fs

type Hand (cards : Card list) =
    member this.Cards = cards

handExtended.fs

type Hand with
    member x.IsRoyalStraightFlush = isRoyalStraightFlush x.Cards

isRoyalStraightFlush.fs

let isRoyalStraightFlush (cards : Card list) = 
    match cards with
    | Ace suit_1 :: King suit_2 :: Queen suit_3 :: Knave suit_4 :: ValueCard (suit_5, 10) :: [] 
        when suit_1 = suit_2 && suit_2 = suit_3 && suit_3 = suit_4 && suit_4 = suit_5
        -> true
    | _ -> false

model.fs

type Suit = | Spades | Hearts | Diamonds | Clubs
 
type Card =
    | ValueCard of Suit * int
    | Knave of Suit
    | Queen of Suit
    | King of Suit
    | Ace of Suit