類型同義詞如何與多功能一起使用？

Question

我看到可以使用多次投影的函數來創建類型同義詞，但是我不太理解應該如何使用它。

這是我剛剛throwParty一個示例，我想它會顯示這樣一個用例，但是我無法定義函數throwParty 。 我將如何使用這種類型的同義詞？

我的例子

type DamagedFurniture = String
type Person           = String
type Friend           = Person
type Acquaintances    = Person -> Friend -> [Person]

throwParty :: Person -> Acquaintances -> DamagedFurniture

Answer 1

相當於

throwParty :: Person -> (Person -> Friend -> [Person]) -> DamagedFurniture

並不是

throwParty :: Person -> Person -> Friend -> [Person] -> DamagedFurniture

您可以做的是：

type AcquaintancesTo a = Person -> Friend -> [Person] -> a

throwParty :: Person -> AcquaintancesTo DamagedFurniture