I have a type synonym declared for the tuple of two Ints:
我为两个Int的元组声明了一个类型同义词:
type Coordinate = (Int, Int)
I'd like to read in Coordinates as part of an IO Action, which boils down to using the read function. Is there a way to leverage the existing Read instance of Tuples to accomplish this?
我想在坐标系中读取IO动作的一部分,归结为使用读取功能。有没有办法利用现有的元组读取实例来实现这一目标?
2 个解决方案
#1
type Coordinate = (Int, Int)
home = read "(1,2)" :: Coordinate
school = read "(10,4)" :: Coordinate
#2
Have you just tried it?
你刚试过吗?
The answer is: yes, the tuple instance is used, there's no need to do anything at all yourself because Coordinate isn't even a different type – it's just a “hard link” to the same type (Int,Int), with all the same functions and class instances.
答案是:是的,使用了元组实例,没有必要自己做任何事情因为Coordinate甚至不是一个不同的类型 - 它只是一个相同类型(Int,Int)的“硬链接”,所有相同的函数和类实例。
#1
type Coordinate = (Int, Int)
home = read "(1,2)" :: Coordinate
school = read "(10,4)" :: Coordinate
#2
Have you just tried it?
你刚试过吗?
The answer is: yes, the tuple instance is used, there's no need to do anything at all yourself because Coordinate isn't even a different type – it's just a “hard link” to the same type (Int,Int), with all the same functions and class instances.
答案是:是的,使用了元组实例,没有必要自己做任何事情因为Coordinate甚至不是一个不同的类型 - 它只是一个相同类型(Int,Int)的“硬链接”,所有相同的函数和类实例。