F# - 运算符重载

您可以重新定义或重载 F# 中大多数可用的内置运算符。因此，程序员也可以将运算符与用户定义类型一起使用。

运算符是用括号括起来的特殊名称的函数。它们必须定义为静态类成员。与任何其他函数一样，重载的运算符具有返回类型和参数列表。

以下示例显示了复数上的 + 运算符：

//overloading + operator
static member (+) (a : Complex, b: Complex) =
Complex(a.x + b.x, a.y + b.y)

上述函数实现了用户定义类 Complex 的加法运算符 (+) 。它添加了两个对象的属性并返回结果 Complex 对象。

运算符重载的实现

下面的程序显示了完整的实现：

//implementing a complex class with +, and - operators
//overloaded
type Complex(x: float, y : float) =
   member this.x = x
   member this.y = y
   //overloading + operator
   static member (+) (a : Complex, b: Complex) =
      Complex(a.x + b.x, a.y + b.y)

   //overloading - operator
   static member (-) (a : Complex, b: Complex) =
      Complex(a.x - b.x, a.y - b.y)

   // overriding the ToString method
   override this.ToString() =
      this.x.ToString() + " " + this.y.ToString()

//Creating two complex numbers
let c1 = Complex(7.0, 5.0)
let c2 = Complex(4.2, 3.1)

// addition and subtraction using the
//overloaded operators
let c3 = c1 + c2
let c4 = c1 - c2

//printing the complex numbers
printfn "%s" (c1.ToString())
printfn "%s" (c2.ToString())
printfn "%s" (c3.ToString())
printfn "%s" (c4.ToString())

编译并执行程序后，将产生以下输出：

7 5
4.2 3.1
11.2 8.1
2.8 1.9