为什么我们不能满足带有类型扩展的F＃静态成员约束？

Question

I'd like to be able to extend types from other libraries with static methods to enable generic arithmetic. Take, for example, the newly minted SIMD-friendly fixed-size VectorN types from Microsoft. They define Zero , they define (+) , they define (/) , but I can't use Array.average on them because they don't define DivideByInt , which I'd be happy to:

open System.Numerics
type Vector2f with 
  static member DivideByInt (v:Vector2f) (i:int) = v / Vector2f(single i, single i)
let bigArray : Vector2f[] = readABigFile()
printf "the average is %A" (Array.average bigArray)

But it won't let me compile, complaining

error FS0001: The type 'Vector2f' does not support the operator 'DivideByInt'

Why does this limitation exist in the F# compiler?

(Edit: essentially the same question was asked previously .)

Answer 1

It is not currently possible to define an operator overload in a type extension. There is an F# language user voice item for this (with quite a lot of votes) and so this is something that might change in future versions of F# (I think it would be great addition that fits nicely with the F# design).

If you absolutely need something like this today, you can either create a lightweight wrapper for your type that adds the operators, or you can use a (somewhat scary) trick that lets you hide the standard operator with a new overloaded one. The following question has both examples: Global operator overloading in F#