Mimic type classes with additional param

gistfile1.fs

type 'a Num = {
    zero: 'a
    add: 'a -> 'a -> 'a
    mult: 'a -> 'a -> 'a
    fromInteger: int -> 'a }

let intNum = {
    zero = 0
    add = (+)
    mult = (*)
    fromInteger = id } 

let floatNum = {
    zero = 0.
    add = (+)
    mult = (*)
    fromInteger = float } 

let square (d: 'a Num) x = d.mult x x

let sumofSquares (d: 'a Num) values =
    values 
      |> Seq.map (square d) 
      |> Seq.fold d.add d.zero

let sumOfSquaresForInts = sumofSquares intNum 
let sumOfSquaresForFloat = sumofSquares floatNum 

let r1 = sumOfSquaresForInts [1;2;3]
let r2 = sumOfSquaresForFloat [1.1; 2.2; 3.1] 

// type error
// let r3 = sumofSquares intNum [1.1;2.2;3.1]