[英]Define F# '**' operator in C#
I see that F# uses the **
operator for powers, so 2 ** 5 = 32
. 我看到F#使用
**
运算符作为幂,所以2 ** 5 = 32
。 This is different from C#, where you have the option to use the '^' operator in your custom types, but for some reason isn't used by the built in number types. 这与C#不同,您可以选择在自定义类型中使用“^”运算符,但由于某些原因,内置数字类型不使用它。
But how do you implement the ** operator in C# for use in an F# project? 但是如何在C#中实现**运算符以用于F#项目?
If I do this in C#: 如果我在C#中这样做:
public static Integer operator ^(Integer left, Integer right)
{
if (Integer.IsNaN(left) || Integer.IsNaN(right)) return NaN;
return left.RaiseToPower(right);
}
It compiles fine, and I can use it the same way as the '+' operator, but neither of these work in F#: 编译很好,我可以像'+'运算符一样使用它,但这些都不适用于F#:
let intgr3 = intgr1 ** intgr2
let intgr3 = intgr1 ^ intgr2
And in C#, this doesn't work: 在C#中,这不起作用:
public static Integer operator **(Integer left, Integer right)
{
if (Integer.IsNaN(left) || Integer.IsNaN(right)) return NaN;
return left.RaiseToPower(right);
}
So how do I define the F# equivalent of the **
operator in C#? 那么如何在C#中定义
**
运算符的F#等价物呢?
Thanks. 谢谢。
As I said in my comments, C# does not let you define new operators and **
is not an operator in C#. 正如我在评论中所说,C#不允许您定义新运算符,
**
不是C#中的运算符。 ^
is an operator, however it is the logical XOR operator, NOT the exponentiation operator. ^
是一个运算符,但它是逻辑XOR运算符,而不是取幂运算符。 This gave me a hint that F# might be translating your C# operator into native F# ( ^^^
for logical XOR). 这给了我一个提示,F#可能会将你的C#操作符转换为本机F#(逻辑XOR为
^^^
)。
So, I created a couple test projects and using your definition of ^
, here's what I found in F#: 所以,我创建了几个测试项目并使用你的定义
^
,这是我在F#中找到的:
open CSLib // CSLib is the C# library
let ( ** ) (x : Integer) (y : Integer) = x.RaiseToPower y
let x = new Integer()
let y = new Integer()
let a = x ^ y // error
let b = x ^^^ y // compiles, but looks like XOR
let c = x ** y // compiles
You can define new global operators in F#, however if you want this to be a general library that may not be acceptable. 您可以在F#中定义新的全局运算符,但是如果您希望这是一个可能不可接受的通用库。
You can define the Exponentiation operator for use in F# by defining a public static method Pow
in the Integer
type in your C# library: 您可以通过在C#库中的
Integer
类型中定义公共静态方法Pow
来定义在F#中使用的Exponentiation运算符:
public static Integer Pow(Integer left, Integer right)
{
if (Integer.IsNaN(left) || Integer.IsNaN(right)) return NaN;
return left.RaiseToPower(right);
}
Then, you are able to use it directly in F# as **
. 然后,您可以直接在F#中使用它作为
**
。 I will note that overloaded operators in C# are not idiomatic so having a Pow
method will seem quite natural to C# users. 我会注意到C#中的重载运算符不是惯用的,所以对于C#用户来说,使用
Pow
方法看起来很自然。
I believe the reason why you can't define a ** operator for your object is that this is not one of the operators supported by the language. 我相信你不能为你的对象定义一个**运算符的原因是这不是该语言支持的运算符之一。 It's not a recognized operator.. Why not just use the Math library http://msdn.microsoft.com/en-us/library/system.math.pow.aspx
它不是一个公认的运算符..为什么不使用数学库http://msdn.microsoft.com/en-us/library/system.math.pow.aspx
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