我嘗試使用下面的代碼打印在Haskell鏈表: data List = Node {value:: Double, next:: List}
| Empty
printList :: List -> String
printList x | x == (Node v n) = show v ++ " " ++ printList n
| otherwise = s
我有以下類型的構造函數和數據構造: data Compose f g x = MkCompose (f (g x))
獲取類型簽名約撰寫的前奏,它表明: MkCompose :: f (g x) -> Compose f g x
爲什麼它顯示的功能等? 當我申請的類型如下: *ComposeExercise> :t MkCompose [[42]]
MkCompose [[42]] ::