open System
open System.Numerics

type Array with    
    static member inline SIMDFold f h (start:'T) (values : 'T[]) =        
        let mutable i = 0;
        let mutable v = Vector<'T>(start)
        while i < values.Length - Vector<'T>.Count do            
            v <- f v (Vector<'T>(values,i))
            i <- i + Vector<'T>.Count
        i <- 0
        let mutable result = start        
        while i < Vector<'T>.Count do
            result <- h result v.[i]
            i <- i+1
        result

let example =
  let r = Random()
  Array.init 1000 (fun _ -> r.NextDouble())    
  |> Array.SIMDFold (fun a e -> a + e*e) (+) 0.0