Scala集合api有一些非常有趣的属性,我想知道如何在Haskell中实现它;或者如果它甚至可能(或者一般来说是一个好主意).我有点像哈斯克尔新手,所以我想听听你的想法.
scala映射定义如下所示:
def map[B,That](f: A => B)(implicit bf: CanBuildFrom[Repr,B,That]): That
解决方法
我们有一些与Scala API一样普遍的东西.它被称为可折叠.
class Foldable t where fold :: Monoid m => t m -> m foldMap :: Monoid m => (a -> m) -> t a -> m foldr :: (a -> b -> b) -> b -> t a -> b foldl :: (a -> b -> a) -> a -> t b -> a foldr1 :: (a -> a -> a) -> t a -> a foldl1 :: (a -> a -> a) -> t a -> a
http://www.haskell.org/ghc/docs/6.12.2/html/libraries/base-4.2.0.1/Data-Foldable.html