0
當我嘗試使用Lens.lensu
從scalaz.7.2.15
,(我檢查http://eed3si9n.com/learning-scalaz/Lens.html)scalaz鏡片不工作
case class Person(id: Int, name: String)
val idLens: Person @> Int = Lens.lensu(
(p, id) => p.copy(id = id),
_.id
)
val nameLens: Person @> String = Lens.lensu(
(p, name) => p.copy(name = name),
_.name
)
val c = idLens <=< nameLens
,但我得到的錯誤:
found : Person @> String
[error] (which expands to) scalaz.LensFamily[Person,Person,String,String]
[error] required: scalaz.LensFamily[?,?,Person,Person]
[error] val c = idLens <=< nameLens
但它是一樣的例子,這段代碼有什麼不好?
啊哈,謝謝這是我的失敗 – lito