spacepaste

open Batteries
class type ['a] number = object ('b)
method value: 'a
method plus: 'b -> 'b
end
class int_wrap (i: int) = object
val i = i
method value = i
method plus (other: int number) = {< i = i + other#value >}
end
class float_wrap (f: float) = object
val f = f
method value = f
method plus (other: float number) = {< f = f +. other#value >}
end
let parse: string -> 'a number = fun s ->
if String.exists s "." then
float_of_string s |> new float_wrap
else
int_of_string s |> new int_wrap