Plays the "linear" version of Solitaire

linear_solitaire.hs

type Card = (Int, Int)
type Deck = [Card]
type Hand = [Card]

collase_one :: Hand -> Hand
collase_one ((_, ra) : _ : _ : (_, rb) : rest) | ra == rb = rest
collase_one (a@(sa, _) : _ : _ : b@(sb, _) : rest) | sa == sb = [a, b] ++ rest
collase_one t = t

collape_all :: Hand -> Hand
collape_all = until (\d -> (collase_one d) == d) collase_one

play :: (Deck, Hand) -> [(Deck, Hand)]
play s@([], _) = [s]
play s@(deck, hand) = s : play (tail deck, collape_all $ head deck : hand)

score :: Deck -> Int
score deck = length . snd . last $ play (deck, [])