下一個檔案編譯但是當我呼叫它時checkDirecRio它給了我：函式中的非詳盡模式checkDirecRio
checkDirecRio :: Mapa -> Bool
checkDirecRio (Mapa _ []) = True
checkDirecRio (Mapa larg ((Rio x, _) : (_,_) : t)) = checkDirecRio (Mapa larg t)
checkDirecRio (Mapa larg ((Rio x, _) : (Rio y, _) : t)) | ((x > 0 && y < 0) || (x < 0 && y > 0)) = True
| otherwise = checkDirecRio (Mapa larg t)
其中結構Mapa定義為：
type Velocidade = Int
data Mapa =
Mapa Largura [(Terreno, [Obstaculo])]
deriving (Show, Read, Eq)
data Terreno
= Rio Velocidade
| Estrada Velocidade
| Relva
deriving (Show, Read, Eq)
data Obstaculo
= Nenhum -- ^ nothing
| Tronco -- ^ wood who can only in Rio being
| Carro -- ^ car who can only in Estrada being
| Arvore -- ^ tree who can only in Relva being
deriving (Show, Read, Eq)
我希望代碼能夠驗證河流Rio是否具有不同的方向，如果 2 條連續河流具有相同的方向，則回傳 False 如果連續河流具有相反的方向，則回傳 True
uj5u.com熱心網友回復：
該函式checkDirecRio具有不完整的模式，因為它沒有涵蓋Terreno除 之外還有 2 個變體的所有變體Rio。您還應該包括涵蓋它們的案例。例如：
checkDirecRio (Mapa _ (((Estrada _), _):_)) = True
checkDirecRio (Mapa _ ((Relva, _):_)) = False
checkDirecRio (Mapa _ [((Rio _), _)]) = False
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標籤：哈斯克尔