Hidden Features of F#

Answer 1

Inlined operators on generic types can have different generic constraints:

type 'a Wrapper = Wrapper of 'a with
  static member inline (+)(Wrapper(a),Wrapper(b)) = Wrapper(a + b)
  static member inline Exp(Wrapper(a)) = Wrapper(exp a)

let objWrapper = Wrapper(obj())
let intWrapper = (Wrapper 1) + (Wrapper 2)
let fltWrapper = exp (Wrapper 1.0)

(* won''t compile *)
let _ = exp (Wrapper 1)