Objective Caml version 1.02+4

#           class point (int) =
  val mutable x : int
  method get_x : int
  method move : int -> unit
end
#   val p : point = <obj>
#   - : int = 7
# - : unit = ()
# - : int = 10
#   val q : point = <obj>
#   - : int * int = 10, 17
#           class color_point (int) (string) =
  val c : string
  val mutable x : int
  method get_x : int
  method move : int -> unit
  method color : string
end
#   val p' : color_point = <obj>
#   - : int * string = 5, "red"
#   val l : point list = [<obj>; <obj>]
#   val get_x : < get_x : 'a; .. > -> 'a = <fun>
# val set_x : < set_x : 'a; .. > -> 'a = <fun>
# - : int list = [10; 5]
#           Characters 6-86:
The type variable 'a is not bound in implicit type definition
  ref = < get : 'a; set : 'a -> unit >
It should be captured by a class type parameter
#           class ref (int) =
  val mutable x : int
  method get : int
  method set : int -> unit
end
#           class 'a ref ('a) =
  val mutable x : 'a
  method get : 'a
  method set : 'a -> unit
end
#   - : int = 2
#             class 'a circle ('a) =
  constraint 'a = < move : int -> unit; .. >
  val mutable center : 'a
  method center : 'a
  method set_center : 'a -> unit
  method move : int -> unit
end
#               class 'a circle ('a) =
  constraint 'a = #point
  val mutable center : 'a
  method center : 'a
  method set_center : 'a -> unit
  method move : int -> unit
end
#   val c : point circle = <obj>
val c' : color_point circle = <obj>
#           class 'a color_circle ('a) =
  constraint 'a = #color_point
  val mutable center : 'a
  method center : 'a
  method set_center : 'a -> unit
  method move : int -> unit
  method color : string
end
#   Characters 28-29:
This expression has type point = < get_x : int; move : int -> unit >
but is here used with type
  #color_point = < get_x : int; move : int -> unit; color : string; .. >
# val c'' : color_point color_circle = <obj>
#   - : color_point circle = <obj>
# Characters 1-4:
This expression cannot be coerced to type
  point circle =
    < center : point; set_center : point -> unit; move : int -> unit >;
it has type
  color_point color_circle =
    < center : color_point; set_center : color_point -> unit;
      move : int -> unit; color : string >
but is here used with type
  < center : color_point; set_center : point -> unit; move : int -> unit;
    color : string >
Type color_point = < get_x : int; move : int -> unit; color : string >
is not compatible with type point = < get_x : int; move : int -> unit >
# Characters 9-55:
Type
  color_point color_circle =
    < center : color_point; set_center : color_point -> unit;
      move : int -> unit; color : string >
is not a subtype of type
  point circle =
    < center : point; set_center : point -> unit; move : int -> unit >
Type color_point -> unit is not a subtype of type point -> unit
Type point = < get_x : int; move : int -> unit > is not a subtype of type
  color_point = < get_x : int; move : int -> unit; color : string >
#         class printable_point (int) =
  val mutable x : int
  method get_x : int
  method move : int -> unit
  method print : unit
end
#   val p : printable_point = <obj>
# 7- : unit = ()
#                     class printable_color_point (int) (string) =
  val c : string
  val mutable x : int
  method get_x : int
  method move : int -> unit
  method color : string
  method print : unit
end
#   val p' : printable_color_point = <obj>
# (7, red)- : unit = ()
#           class functional_point (int) : 'a =
  val x : int
  method get_x : int
  method move : int -> 'a
end
#   val p : functional_point = <obj>
#   - : int = 7
# - : int = 10
# - : int = 7
#   - : (< get_x : int; move : int -> 'a; .. > as 'a) -> functional_point = <fun>
#                                                                       class virtual 'a lst (unit) =
  method map : ('a -> 'a) -> 'a lst
  method iter : ('a -> unit) -> unit
  method print : ('a -> unit) -> unit
  virtual null : bool
  virtual hd : 'a
  virtual tl : 'a lst
end
class 'a nil (unit) =
  method null : bool
  method hd : 'a
  method tl : 'a lst
  method map : ('a -> 'a) -> 'a lst
  method iter : ('a -> unit) -> unit
  method print : ('a -> unit) -> unit
end
class 'a cons ('a) ('a lst) =
  val h : 'a
  val t : 'a lst
  method null : bool
  method hd : 'a
  method tl : 'a lst
  method map : ('a -> 'a) -> 'a lst
  method iter : ('a -> unit) -> unit
  method print : ('a -> unit) -> unit
end
#   val l1 : int cons = <obj>
#   (3::10::[])- : unit = ()
#   val l2 : int lst = <obj>
# (4::11::[])- : unit = ()
#       val map_list : ('a -> 'b) -> 'a lst -> 'b lst = <fun>
#   val p1 : printable_color_point lst = <obj>
# ((3, red)::(10, red)::[])- : unit = ()
#           class virtual comparable (unit) : 'a = virtual leq : 'a -> bool end
#             class int_comparable (int) : 'a =
  val x : int
  method leq : 'a -> bool
  method x : int
end
#           class int_comparable2 (int) : 'a =
  method leq : 'a -> bool
  method x : int
  method set_x : int -> unit
end
#                         class 'a sorted_list (unit) =
  constraint 'a = #comparable
  val mutable l : 'a list
  method add : 'a -> unit
  method hd : 'a
end
#   val l : _#comparable sorted_list = <obj>
# val c : int_comparable = <obj>
# - : unit = ()
#   val c2 : int_comparable2 = <obj>
# Characters 7-9:
This expression cannot be coerced to type
  int_comparable = < leq : int_comparable -> bool; x : int >;
it has type
  int_comparable2 =
    < leq : int_comparable2 -> bool; x : int; set_x : int -> unit >
but is here used with type
  < leq : int_comparable -> bool; x : int; set_x : int -> unit >
Type
  int_comparable2 =
    < leq : int_comparable2 -> bool; x : int; set_x : int -> unit >
is not compatible with type
  int_comparable = < leq : int_comparable -> bool; x : int >
# - : unit = ()
#             class int_comparable3 (int) =
  val mutable x : int
  method leq : int_comparable -> bool
  method x : int
  method setx : int -> unit
end
#   val c3 : int_comparable3 = <obj>
# - : unit = ()
# Characters 25-27:
This expression has type
  int_comparable3 =
    < leq : int_comparable -> bool; x : int; setx : int -> unit >
but is here used with type
  < leq : 'a -> bool; setx : int -> unit; x : int > as 'a
Type int_comparable = < leq : int_comparable -> bool; x : int >
is not compatible with type
  int_comparable3 =
    < leq : int_comparable -> bool; x : int; setx : int -> unit >
#   val sort : (#comparable as 'a) list -> 'a list = <fun>
#     val pr : < x : int; .. > list -> unit = <fun>
#   val l : int_comparable list = [<obj>; <obj>; <obj>]
# 5 2 4 
- : unit = ()
# 2 4 5 
- : unit = ()
# val l : int_comparable2 list = [<obj>; <obj>]
# 2 0 
- : unit = ()
# 0 2 
- : unit = ()
#     val min : (#comparable as 'a) -> 'a -> 'a = <fun>
#   - : int = 7
# - : int = 3
#                                 class 'a link ('a) : 'b =
  val mutable next : 'b option
  val mutable x : 'a
  method x : 'a
  method next : 'b option
  method set_x : 'a -> unit
  method set_next : 'b option -> unit
  method append : 'b option -> unit
end
#                   class 'a double_link ('a) : 'b =
  val mutable next : 'b option
  val mutable prev : 'b option
  val mutable x : 'a
  method x : 'a
  method next : 'b option
  method set_x : 'a -> unit
  method set_next : 'b option -> unit
  method append : 'b option -> unit
  method prev : 'b option
  method set_prev : 'b option -> unit
end
#           val fold_right : ('a -> 'b -> 'b) -> 'a #link option -> 'b -> 'b = <fun>
#                                       class calculator (unit) : 'a =
  val mutable acc : float
  val mutable arg : float
  val mutable equals : 'a -> float
  method arg : float
  method acc : float
  method add : 'a
  method enter : float -> 'a
  method equals : float
  method sub : 'a
end
#   - : float = 5
# - : float = 1.5
# - : float = 15
#                       class calculator (unit) : 'a =
  val mutable acc : float
  val mutable arg : float
  val mutable equals : 'a -> float
  method arg : float
  method acc : float
  method add : 'a
  method enter : float -> 'a
  method equals : float
  method sub : 'a
end
#   - : float = 5
# - : float = 1.5
# - : float = 15
#                                 class calculator (float) (float) =
  val acc : float
  val arg : float
  method enter : float -> calculator
  method add : calculator_add
  method sub : calculator_sub
  method equals : float
end
class calculator_add (float) (float) =
  val acc : float
  val arg : float
  method enter : float -> calculator
  method add : calculator_add
  method sub : calculator_sub
  method equals : float
end
class calculator_sub (float) (float) =
  val acc : float
  val arg : float
  method enter : float -> calculator
  method add : calculator_add
  method sub : calculator_sub
  method equals : float
end
#   val calculator : calculator = <obj>
#   - : float = 5
# - : float = 1.5
# - : float = 15
#