是否有“纯粹适用的任一”的标准名称或实现？

我经常发现我所谓的“纯粹应用性”的用处Either", i.e. Either与Applicative只要我们不实现一个实例就可用Monad实例也是如此。

newtype AEither e a = AEither { unAEither :: Either e a }
  deriving Functor

-- technically we only need Semigroup
instance Monoid e => Applicative (AEither e) where
  pure a = AEither (pure a)
  AEither e1 <*> AEither e2 = AEither (combine e1 e2) where
    combine (Right f) (Right a) = Right (f a)
    combine (Left m1) (Left m2) = Left (m1 <> m2)
    combine (Left m ) _         = Left m
    combine _         (Left m ) = Left m

这是一个非常有用的Applicative因为它提供了比“错误总结”更强大的概念Either's Monad实例可以做。为此，我发现自己一遍又一遍地实施它。

某处有标准实例吗？有没有标准的名字？

这看起来与 Acc Validation 类型非常相似validation包裹：http://hackage.haskell.org/package/validation-0.3.1/docs/Data-Validation.html http://hackage.haskell.org/package/validation-0.3.1/docs/Data-Validation.html

Edit:

特别是以下实例声明：

instance Semigroup err => Apply (AccValidation err) where
  AccFailure e1 <.> AccFailure e2 =
    AccFailure (e1 <> e2)
  AccFailure e1 <.> AccSuccess _  =
    AccFailure e1
  AccSuccess _  <.> AccFailure e2 =
    AccFailure e2
  AccSuccess f  <.> AccSuccess a  =
    AccSuccess (f a)