函数 – Scala是否具有与Haskell的“$”类似的运算符？
发布时间：2020-12-16 09:13:01 所属栏目：安全 来源：网络整理
导读：Scala是否具有类似于 Haskell’s $ 的操作符？ -- | Application operator. This operator is redundant,since ordinary-- application @(f x)@ means the same as @(f '$' x)@. However,'$' has-- low,right-associative binding precedence,so it sometime
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Scala是否具有类似于
Haskell’s
$的操作符？
-- | Application operator. This operator is redundant,since ordinary
-- application @(f x)@ means the same as @(f '$' x)@. However,'$' has
-- low,right-associative binding precedence,so it sometimes allows
-- parentheses to be omitted; for example:
--
-- > f $g $h x = f (g (h x))
--
-- It is also useful in higher-order situations,such as @'map' ('$' 0) xs@,-- or @'Data.List.zipWith' ('$') fs xs@.
{-# INLINE ($) #-}
($) :: (a -> b) -> a -> b
f $x = f x
解决方法
是的,它写成“适用”
fn apply arg 没有标准的标点符号操作符,但是通过库创建添加一个可以很容易. class RichFunction[-A,+B](fn: Function1[A,B]){ def $(a:A):B = fn(a)}
implicit def function2RichFunction[-A,+B](t: Function1[A,B]) = new RichFunction[A,B](t)
一般来说,虽然Scala代码比Java更密集,但它并不像Haskell那么密集.因此,创建像“$”和“”这样的操作符的回报较少. （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |