如何编写与Array.sum兼容的新类型?

sum

type Foo(value:int) = 
  member x.Value = value
  // Two members that are needed by 'Array.sum'
  static member (+) (a:Foo, b:Foo) = Foo(a.Value + b.Value)
  static member Zero = Foo(0)
  // Not needed for 'Array.sum', but allows 'Array.average'
  static member DivideByInt(a:Foo, n:int) = Foo(a.Value / n)

这个 函数以返回的值开始 Zero 然后添加 Foo 使用过载 + 操作员( average

let a = Array.init 10 (fun n -> Foo(n)) 
let sum = Array.sum a 
sum.Value // Returns 45

不可能。

当您想使用任何数组方法(sum等)时,您必须为数据存储使用数组类型。