How can I use Seq.sum for any .Net value types?

Question

I'm looking to make a function that handles a seq of any numeric type of data (int, float, double), does a little computation on it via mapping, then does a summation of these calculated values. The problem I am running into is that Seq.sum (or really just '(+)' in general) causes the type parameters to be integer, or just give a flat out error. It seems there there should be a way to make this work by using type constraints but I can't seem to get it.

type ValueWithComputation<'v> = {Value: seq<'v>; Computation: 'v -> 'v}

let calculateAndCombine (x: ValueWithComputation<'v>) = 
    x.Value
    |> Seq.map x.Computation
    |> Seq.sum // sometimes gives error: "Could not resolve the ambiguity inherent in the use of operator '(+)'

let x = {Value= {1..10}; Computation= (fun x->x*2)}
let y = {Value= {(1.0)..(10.0)}; Computation= (fun x->x*x)}

let totalX = calculateAndCombine x //this causes the code force 'v to be int
let totalY = calculateAndCombine y //gives an error since this isn't an int

This seems similar to F# generics / function overloading syntax but it didn't really explain how to get it to work for all value types.

Answer 1

I got it to work like this. Read the answer linked by Foggy Finder. Then you need additionally the static member Zero for the sum to work.

type ValueWithComputation< ^T when ^T: (static member (+): ^T * ^T -> ^T) and ^T: (static member Zero: ^T)> = 
  { Value: seq< ^T>
    Computation: ^T -> ^T }

let inline calculateAndCombine x = 
    x.Value
    |> Seq.map x.Computation
    |> Seq.sum

let x = {Value= {1..10}; Computation= (fun x->x*2)}
let y = {Value= {(1.0)..(10.0)}; Computation= (fun x->x*x)}

let totalX = calculateAndCombine x
let totalY = calculateAndCombine y