在Scala中,是否有减少泛型类型的简写? [英] In Scala, is there a shorthand for reducing a generic type's arity?
问题描述
我想调用Scalaz的纯粹的
方法来为State monad添加一个值。以下工作:
类型IntState [A] =状态[Int,A]
val a =a .pure [IntState]
a(1)
(Int,java.lang.String)=(1,a)
我也可以消除类型别名(谢谢Scalaz的Pure.scala):
val a =a.pure [({type T [A] = State [Int,A]})#b]
a(1)
(Int,java.lang.String)=(1 ,a)
但这非常笨重。是否有更短的方法来合成这样的类型?类似于函数文字的占位符语法,是不是有这样的: b $ b
对于Scala中的简洁部分类型应用程序(arity-2) ,你可以在下面加入类型符号。
type![F [_,_],X] = TF {type! [Y] = F [X,Y]}
a.pure [(State!Int)#!]
请注意,我们可以为两个arity类型的构造函数(或类型别名)插入符号。
I want to call Scalaz's pure
method to put a value into the State monad. The following works:
type IntState[A] = State[Int, A]
val a = "a".pure[IntState]
a(1)
(Int, java.lang.String) = (1,a)
I can also eliminate the type alias (thanks Scalaz's Pure.scala):
val a = "a".pure[({type T[A]=State[Int,A]})#T]
a(1)
(Int, java.lang.String) = (1,a)
But that is extremely clunky. Is there a shorter way to synthesize a type like this? Like placeholder syntax for function literals, is there something like:
"a".pure[State[Int, *]]
For concise partial type application (arity-2) in Scala, you can infix type notation as followings.
type ![F[_, _], X] = TF { type ![Y] = F[X, Y] }
"a".pure[(State!Int)# !]
Note that we can infix notation for two arity type constructor (or type alias).
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