ocaml/testsuite/tests/typing-poly/poly.ml.reference

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# * * * # type 'a t = { t : 'a; }
# type 'a fold = { fold : 'b. f:('b -> 'a -> 'b) -> init:'b -> 'b; }
# val f : 'a list -> 'a fold = <fun>
# - : int = 6
# class ['b] ilist :
'b list ->
object ('c)
val l : 'b list
method add : 'b -> 'c
method fold : f:('a -> 'b -> 'a) -> init:'a -> 'a
end
# class virtual ['a] vlist :
object ('c)
method virtual add : 'a -> 'c
method virtual fold : f:('b -> 'a -> 'b) -> init:'b -> 'b
end
# class ilist2 :
int list ->
object ('a)
val l : int list
method add : int -> 'a
method fold : f:('b -> int -> 'b) -> init:'b -> 'b
end
# val ilist2 : 'a list -> 'a vlist = <fun>
# class ['a] ilist3 :
'a list ->
object ('c)
val l : 'a list
method add : 'a -> 'c
method fold : f:('b -> 'a -> 'b) -> init:'b -> 'b
end
# class ['a] ilist4 :
'a list ->
object ('c)
val l : 'a list
method add : 'a -> 'c
method fold : f:('b -> 'a -> 'b) -> init:'b -> 'b
end
# class ['a] ilist5 :
'a list ->
object ('c)
val l : 'a list
method add : 'a -> 'c
method fold : f:('b -> 'a -> 'b) -> init:'b -> 'b
method fold2 : f:('b -> 'a -> 'b) -> init:'b -> 'b
end
# class ['a] ilist6 :
'a list ->
object ('c)
val l : 'a list
method add : 'a -> 'c
method fold : f:('b -> 'a -> 'b) -> init:'b -> 'b
method fold2 : f:('b -> 'a -> 'b) -> init:'b -> 'b
end
# class virtual ['a] olist :
object method virtual fold : f:('a -> 'c -> 'c) -> init:'c -> 'c end
# class ['a] onil :
object method fold : f:('a -> 'c -> 'c) -> init:'c -> 'c end
# class ['a] ocons :
hd:'a ->
tl:'a olist ->
object
val hd : 'a
val tl : 'a olist
method fold : f:('a -> 'c -> 'c) -> init:'c -> 'c
end
# class ['a] ostream :
hd:'a ->
tl:'a ostream ->
object
val hd : 'a
val tl : < empty : bool; fold : 'c. f:('a -> 'c -> 'c) -> init:'c -> 'c >
method empty : bool
method fold : f:('a -> 'c -> 'c) -> init:'c -> 'c
end
# class ['a] ostream1 :
hd:'a ->
tl:'b ->
object ('b)
val hd : 'a
val tl : 'b
method fold : f:('a -> 'c -> 'c) -> init:'c -> 'c
method hd : 'a
method tl : 'b
end
# class vari : object method m : [< `A | `B | `C ] -> int end
# class vari : object method m : [< `A | `B | `C ] -> int end
# module V : sig type v = [ `A | `B | `C ] val m : [< v ] -> int end
# class varj : object method m : [< V.v ] -> int end
# module type T =
sig class vari : object method m : [< `A | `B | `C ] -> int end end
# module M0 :
sig class vari : object method m : [< `A | `B | `C ] -> int end end
# module M : T
# val v : M.vari = <obj>
# - : int = 1
# class point :
x:int ->
y:int -> object val x : int val y : int method x : int method y : int end
# class color_point :
x:int ->
y:int ->
color:string ->
object
val color : string
val x : int
val y : int
method color : string
method x : int
method y : int
end
# class circle :
#point ->
r:int ->
object val p : point val r : int method distance : #point -> float end
# val p0 : point = <obj>
val p1 : point = <obj>
val cp : color_point = <obj>
val c : circle = <obj>
val d : float = 11.
# val f : < m : 'a. 'a -> 'a > -> < m : 'b. 'b -> 'b > = <fun>
# Characters 41-42:
let f (x : < m : 'a. 'a -> 'a list >) = (x : < m : 'b. 'b -> 'c >)
^
Error: This expression has type < m : 'b. 'b -> 'b list >
but an expression was expected of type < m : 'b. 'b -> 'c >
The universal variable 'b would escape its scope
# class id : object method id : 'a -> 'a end
# class type id_spec = object method id : 'a -> 'a end
# class id_impl : object method id : 'a -> 'a end
# class a : object method m : bool end
and b : object method id : 'a -> 'a end
# Characters 72-77:
method id x = x
^^^^^
Error: This method has type 'a -> 'a which is less general than 'b. 'b -> 'a
# Characters 75-80:
method id x = x
^^^^^
Error: This method has type 'a -> 'a which is less general than 'b. 'b -> 'a
# Characters 80-85:
method id _ = x
^^^^^
Error: This method has type 'b -> 'b which is less general than 'a. 'a -> 'a
# Characters 92-159:
............x =
match r with
None -> r <- Some x; x
| Some y -> y
Error: This method has type 'b -> 'b which is less general than 'a. 'a -> 'a
# class c : object method m : 'a -> 'b -> 'a end
# val f1 : id -> int * bool = <fun>
# val f2 : id -> int * bool = <fun>
# Characters 24-28:
let f3 f = f#id 1, f#id true
^^^^
Error: This expression has type bool but an expression was expected of type
int
# val f4 : id -> int * bool = <fun>
# class c : object method m : #id -> int * bool end
# class id2 : object method id : 'a -> 'a method mono : int -> int end
# val app : int * bool = (1, true)
# Characters 0-25:
type 'a foo = 'a foo list
^^^^^^^^^^^^^^^^^^^^^^^^^
Error: The type abbreviation foo is cyclic
# class ['a] bar : 'a -> object end
# type 'a foo = 'a foo bar
# - : (< m : 'a. 'a * 'b > as 'b) -> 'c * 'b = <fun>
# - : (< m : 'a. 'b * 'a list > as 'b) -> 'b * 'c list = <fun>
# val f :
(< m : 'b. 'a * (< n : 'b; .. > as 'b) > as 'a) ->
'a * (< n : 'c; .. > as 'c) = <fun>
# - : (< p : 'b. < m : 'b; n : 'a; .. > as 'b > as 'a) ->
(< m : 'c; n : 'a; .. > as 'c)
= <fun>
# - : (< m : 'a. 'a * < p : 'b. 'b * 'd * 'c > as 'd > as 'c) ->
('f * < p : 'b. 'b * 'e * 'c > as 'e)
= <fun>
# - : < m : 'a. < p : 'a; .. > as 'b > -> 'b = <fun>
# type sum = T of < id : 'a. 'a -> 'a >
# - : sum -> 'a -> 'a = <fun>
# type record = { r : < id : 'a. 'a -> 'a >; }
# - : record -> 'a -> 'a = <fun>
# - : record -> 'a -> 'a = <fun>
# class myself : object ('b) method self : 'a -> 'b end
# class number :
object ('b)
val num : int
method num : int
method prev : 'b
method succ : 'b
method switch : zero:(unit -> 'a) -> prev:('b -> 'a) -> 'a
end
# val id : 'a -> 'a = <fun>
# class c : object method id : 'a -> 'a end
# class c' : object method id : 'a -> 'a end
# class d :
object
val mutable count : int
method count : int
method id : 'a -> 'a
method old : 'a -> 'a
end
# class ['a] olist :
'a list ->
object ('c)
val l : 'a list
method cons : 'a -> 'c
method fold : f:('a -> 'b -> 'b) -> init:'b -> 'b
end
# val sum : int #olist -> int = <fun>
# val count : 'a #olist -> int = <fun>
# val append : 'a #olist -> ('a #olist as 'b) -> 'b = <fun>
# type 'a t = unit
# class o : object method x : [> `A ] t -> unit end
# class c : object method m : d end
and d : ?x:int -> unit -> object end
# class d : ?x:int -> unit -> object end
and c : object method m : d end
# class type numeral = object method fold : ('a -> 'a) -> 'a -> 'a end
class zero : object method fold : ('a -> 'a) -> 'a -> 'a end
class next : #numeral -> object method fold : ('a -> 'a) -> 'a -> 'a end
# class type node_type = object method as_variant : [> `Node of node_type ] end
# class node : node_type
# class node : object method as_variant : [> `Node of node_type ] end
# type bad = { bad : 'a. 'a option ref; }
# Characters 17-25:
let bad = {bad = ref None};;
^^^^^^^^
Error: This field value has type 'b option ref which is less general than
'a. 'a option ref
# type bad2 = { mutable bad2 : 'a. 'a option ref option; }
# val bad2 : bad2 = {bad2 = None}
# Characters 13-28:
bad2.bad2 <- Some (ref None);;
^^^^^^^^^^^^^^^
Error: This field value has type 'b option ref option
which is less general than 'a. 'a option ref option
# val f : < m : 'a. < p : 'a * 'c > as 'c > -> 'b -> unit = <fun>
# val f : < m : 'a. 'a * (< p : int * 'b > as 'b) > -> 'b -> unit = <fun>
# type 'a t = [ `A of 'a ]
# class c : object method m : ([> 'a t ] as 'a) -> unit end
# class c : object method m : ([> 'a t ] as 'a) -> unit end
# class c : object method m : ([> 'a t ] as 'a) -> 'a end
# class c : object method m : ([> `A ] as 'a) option -> 'a end
# Characters 145-166:
object method virtual visit : 'a.('a visitor -> 'a) end;;
^^^^^^^^^^^^^^^^^^^^^
Error: The universal type variable 'a cannot be generalized:
it escapes its scope.
# type ('a, 'b) list_visitor = < caseCons : 'b -> 'b list -> 'a; caseNil : 'a >
type 'b alist = < visit : 'a. ('a, 'b) list_visitor -> 'a >
class type ct = object ('a) method fold : ('b -> 'a -> 'b) -> 'b -> 'b end
type t = { f : 'a 'b. ('b -> (#ct as 'a) -> 'b) -> 'b; }
# Characters 15-25:
type t = u and u = t;;
^^^^^^^^^^
Error: The type abbreviation t is cyclic
# class ['a] a : object constraint 'a = [> `A of 'a a ] end
type t = [ `A of t a ]
# Characters 71-80:
type ('a,'b) t constraint 'a = 'b and ('a,'b) u = ('a,'b) t;;
^^^^^^^^^
Error: Constraints are not satisfied in this type.
Type ('a, 'b) t should be an instance of ('c, 'c) t
# type 'a t = 'a
and u = int t
# type 'a t constraint 'a = int
# Characters 26-32:
type 'a u = 'a and 'a v = 'a u t;;
^^^^^^
Error: Constraints are not satisfied in this type.
Type 'a u t should be an instance of int t
# type 'a u = 'a constraint 'a = int
and 'a v = 'a u t constraint 'a = int
# type g = int
# type 'a t = unit constraint 'a = g
# Characters 26-32:
type 'a u = 'a and 'a v = 'a u t;;
^^^^^^
Error: Constraints are not satisfied in this type.
Type 'a u t should be an instance of g t
# type 'a u = 'a constraint 'a = g
and 'a v = 'a u t constraint 'a = g
# Characters 34-58:
type 'a u = < m : 'a v > and 'a v = 'a list u;;
^^^^^^^^^^^^^^^^^^^^^^^^
Error: In the definition of v, type 'a list u should be 'a u
# type 'a t = 'a
type 'a u = A of 'a t
# type 'a t = < a : 'a >
# - : ('a t as 'a) -> 'a t = <fun>
# type u = 'a t as 'a
# type t = A | B
# - : [> `A ] * t -> int = <fun>
# - : [> `A ] * t -> int = <fun>
# - : [> `A ] option * t -> int = <fun>
# - : [> `A ] option * t -> int = <fun>
# - : t * [< `A | `B ] -> int = <fun>
# - : [< `A | `B ] * t -> int = <fun>
# Characters 0-41:
function (`A|`B), _ -> 0 | _,(`A|`B) -> 1;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
(`AnyExtraTag, `AnyExtraTag)
- : [> `A | `B ] * [> `A | `B ] -> int = <fun>
# Characters 0-29:
function `B,1 -> 1 | _,1 -> 2;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
(_, 0)
Characters 21-24:
function `B,1 -> 1 | _,1 -> 2;;
^^^
Warning 11: this match case is unused.
- : [< `B ] * int -> int = <fun>
# Characters 0-29:
function 1,`B -> 1 | 1,_ -> 2;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
(0, _)
Characters 21-24:
function 1,`B -> 1 | 1,_ -> 2;;
^^^
Warning 11: this match case is unused.
- : int * [< `B ] -> int = <fun>
# Characters 64-135:
type ('a, 'b) a = 'a -> unit constraint 'a = [> `B of ('a, 'b) b as 'b]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Constraints are not satisfied in this type.
Type
([> `B of 'a ], 'a) b as 'a
should be an instance of
(('b, [> `A of 'b ] as 'c) a as 'b, 'c) b
# * class type ['a, 'b] a =
object
constraint 'a = < as_a : ('a, 'b) a as 'c; b : 'b; .. >
constraint 'b = < a : 'a; as_b : ('a, 'b) b; .. >
method as_a : 'c
method b : 'b
end
and ['a, 'b] b =
object
constraint 'a = < as_a : ('a, 'b) a; b : 'b; .. >
constraint 'b = < a : 'a; as_b : ('a, 'b) b; .. >
method a : 'a
method as_b : ('a, 'b) b
end
class type ['a] ca =
object ('b)
constraint 'a = < a : 'b; as_b : ('b, 'a) b; .. >
method as_a : ('b, 'a) a
method b : 'a
end
class type ['a] cb =
object ('b)
constraint 'a = < as_a : ('a, 'b) a; b : 'b; .. >
method a : 'a
method as_b : ('a, 'b) b
end
type bt = 'a ca cb as 'a
# class c : object method m : int end
# val f : unit -> c = <fun>
# val f : unit -> c = <fun>
# Characters 11-60:
let f () = object method private n = 1 method m = {<>}#n end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Warning 15: the following private methods were made public implicitly:
n.
val f : unit -> < m : int; n : int > = <fun>
# Characters 11-56:
let f () = object (self:c) method n = 1 method m = 2 end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This object is expected to have type c but actually has type
< m : int; n : 'a >
The first object type has no method n
# Characters 11-69:
let f () = object (_:'s) constraint 's = < n : int > method m = 1 end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This object is expected to have type < n : int > but actually has type
< m : 'a >
The second object type has no method n
# Characters 66-124:
object (self: 's) method x = 3 method private m = self end
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This object is expected to have type < x : int; .. >
but actually has type < x : int >
Self type cannot be unified with a closed object type
# val o : < x : int > = <obj>
# Characters 76-77:
(x : <m : 'a. 'a * (<m:'b. 'a * <m:'c. 'c * 'bar> > as 'bar) >);;
^
Error: This expression has type < m : 'a. 'a * < m : 'a * 'b > > as 'b
but an expression was expected of type
< m : 'a. 'a * (< m : 'a * < m : 'c. 'c * 'd > > as 'd) >
Types for method m are incompatible
# Characters 176-177:
let f (x : foo') = (x : bar');;
^
Error: This expression has type foo' = < m : 'a. 'a * 'a foo >
but an expression was expected of type bar' = < m : 'a. 'a * 'a bar >
Type 'a foo = < m : 'a * 'a foo > is not compatible with type
'a bar = < m : 'a * < m : 'c. 'c * 'a bar > >
Type 'a foo = < m : 'a * 'a foo > is not compatible with type
< m : 'c. 'c * 'a bar >
Types for method m are incompatible
# Characters 67-68:
(x : <m : 'b. 'b * ('b * <m : 'c. 'c * ('c * 'bar)>)> as 'bar);;
^
Error: This expression has type
< m : 'b. 'b * ('b * < m : 'c. 'c * 'a > as 'a) >
but an expression was expected of type
< m : 'b. 'b * ('b * < m : 'c. 'c * ('c * 'd) >) > as 'd
Types for method m are incompatible
# Characters 66-67:
(x : <m : 'b. 'b * ('b * <m : 'c. 'c * ('b * 'bar)>)> as 'bar);;
^
Error: This expression has type
< m : 'b. 'b * ('b * < m : 'c. 'c * 'a > as 'a) >
but an expression was expected of type
< m : 'b. 'b * ('b * < m : 'c. 'c * ('b * 'd) >) > as 'd
Types for method m are incompatible
# Characters 51-52:
(x : <m : 'b. 'b * ('b * <m:'c. 'c * 'bar> as 'bar)>);;
^
Error: This expression has type < m : 'b. 'b * ('b * 'a) > as 'a
but an expression was expected of type
< m : 'b. 'b * ('b * < m : 'c. 'c * 'd > as 'd) >
Types for method m are incompatible
# Characters 14-115:
....(x : <m : 'a. 'a -> ('a * <m:'c. 'c -> 'bar> as 'bar)>
:> <m : 'a. 'a -> ('a * 'foo)> as 'foo)..
Error: Type < m : 'a. 'a -> ('a * (< m : 'c. 'c -> 'b as 'e > as 'd) as 'b) >
is not a subtype of < m : 'a. 'a -> ('a * 'f as 'h) as 'g > as 'f
Type 'c. 'e is not a subtype of 'a. 'g
# Characters 88-150:
= struct let f (x : <m : 'a. 'a * ('a * 'foo)> as 'foo) = () end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Signature mismatch:
...
Values do not match:
val f : (< m : 'a. 'a * ('a * 'b) > as 'b) -> unit
is not included in
val f : < m : 'b. 'b * ('b * < m : 'c. 'c * 'a > as 'a) > -> unit
# Characters 78-132:
= struct type t = <m : 'a. 'a * ('a * 'foo)> as 'foo end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Signature mismatch:
Modules do not match:
sig type t = < m : 'a. 'a * ('a * 'b) > as 'b end
is not included in
sig type t = < m : 'b. 'b * ('b * < m : 'c. 'c * 'a > as 'a) > end
Type declarations do not match:
type t = < m : 'a. 'a * ('a * 'b) > as 'b
is not included in
type t = < m : 'b. 'b * ('b * < m : 'c. 'c * 'a > as 'a) >
# module M : sig type 'a t type u = < m : 'a. 'a t > end
# module M : sig type 'a t val f : < m : 'a. 'a t > -> int end
# module M : sig type 'a t val f : < m : 'a. 'a t > -> int end
# val f :
(< m : 'a. 'a -> (< m : 'a. 'a -> 'c * < > > as 'c) * < .. >; .. > as 'b) ->
'b -> bool = <fun>
# type t = [ `A | `B ]
# type v = private [> t ]
# - : t -> v = <fun>
# type u = private [< t ]
# - : u -> v = <fun>
# Characters 9-21:
fun x -> (x : v :> u);;
^^^^^^^^^^^^
Error: Type v = [> `A | `B ] is not a subtype of u = [< `A | `B ]
# type v = private [< t ]
# Characters 9-21:
fun x -> (x : u :> v);;
^^^^^^^^^^^^
Error: Type u = [< `A | `B ] is not a subtype of v = [< `A | `B ]
# type p = < x : p >
# type q = private < x : p; .. >
# - : q -> p = <fun>
# Characters 9-21:
fun x -> (x : p :> q);;
^^^^^^^^^^^^
Error: Type p = < x : p > is not a subtype of q = < x : p; .. >
# Characters 14-100:
..(x : <m:'a. (<p:int;..> as 'a) -> int>
:> <m:'b. (<p:int;q:int;..> as 'b) -> int>)..
Error: Type < m : 'a. (< p : int; .. > as 'a) -> int > is not a subtype of
< m : 'b. (< p : int; q : int; .. > as 'b) -> int >
Type < p : int; q : int; .. > as 'c is not a subtype of
< p : int; .. > as 'd
# val f2 :
< m : 'a. (< p : < a : int >; .. > as 'a) -> int > ->
< m : 'b. (< p : < a : int; b : int >; .. > as 'b) -> int > = <fun>
# Characters 13-107:
..(x : <m:'a. (<p:<a:int;b:int>;..> as 'a) -> int>
:> <m:'b. (<p:<a:int>;..> as 'b) -> int>)..
Error: Type < m : 'a. (< p : < a : int; b : int >; .. > as 'a) -> int >
is not a subtype of < m : 'b. (< p : < a : int >; .. > as 'b) -> int >
Type < a : int > is not a subtype of < a : int; b : int >
# Characters 11-55:
let f4 x = (x : <p:<a:int;b:int>;..> :> <p:<a:int>;..>);;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Type < p : < a : int; b : int >; .. > is not a subtype of
< p : < a : int >; .. >
The second object type has no method b
# val f5 :
< m : 'a. [< `A of < p : int > ] as 'a > ->
< m : 'b. [< `A of < > ] as 'b > = <fun>
# Characters 13-83:
(x : <m:'a. [< `A of < > ] as 'a> :> <m:'a. [< `A of <p:int> ] as 'a>);;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: Type < m : 'a. [< `A of < > ] as 'a > is not a subtype of
< m : 'b. [< `A of < p : int > ] as 'b >
Type < > is not a subtype of < p : int >
# val f : < m : 'a. 'a -> 'a > -> < m : 'a. 'a -> 'a > = <fun>
# - : < m : 'a. 'a -> 'a > -> 'b -> 'b = <fun>
# val f : < m : 'a. 'a -> 'a > * 'b -> < m : 'a. 'a -> 'a > = <fun>
# - : < m : 'a. 'a -> 'a > -> 'b -> 'b = <fun>
# val f : < m : 'a. 'a -> 'a > -> < m : 'a. 'a -> 'a > array = <fun>
# - : < m : 'a. 'a -> 'a > -> 'b -> 'b = <fun>
# class c : object method id : 'a -> 'a end
# type u = c option
# val just : 'a option -> 'a = <fun>
# val f : c -> 'a -> 'a = <fun>
# val g : c -> 'a -> 'a = <fun>
# val h : < id : 'a; .. > -> 'a = <fun>
# type 'a u = c option
# val just : 'a option -> 'a = <fun>
# val f : c -> 'a -> 'a = <fun>
# val f : 'a -> int = <fun>
val g : 'a -> int = <fun>
# type 'a t = Leaf of 'a | Node of ('a * 'a) t
# val depth : 'a t -> int = <fun>
# Characters 34-74:
function Leaf _ -> 1 | Node x -> 1 + d x
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This definition has type 'a t -> int which is less general than
'a0. 'a0 t -> int
# Characters 34-78:
function Leaf x -> x | Node x -> 1 + depth x;; (* fails *)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This definition has type int t -> int which is less general than
'a. 'a t -> int
# Characters 34-74:
function Leaf x -> x | Node x -> depth x;; (* fails *)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This definition has type 'a t -> 'a which is less general than
'a0. 'a0 t -> 'a
# Characters 38-78:
function Leaf x -> x | Node x -> depth x;; (* fails *)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This definition has type 'b. 'b t -> 'b which is less general than
'a 'b. 'a t -> 'b
# val r : 'a list * '_b list ref = ([], {contents = []})
val q : unit -> 'a list * '_b list ref = <fun>
# val f : 'a -> 'a = <fun>
# val zero : [> `B of 'a | `Int of int ] as 'a = `Int 0
# Characters 39-45:
let zero : 'a. [< `Int of int] as 'a = `Int 0;; (* fails *)
^^^^^^
Error: This expression has type [> `Int of int ]
but an expression was expected of type [< `Int of int ]
Types for tag `Int are incompatible
# type t = { f : 'a. [> `B of 'a | `Int of int ] as 'a; }
val zero : t = {f = `Int 0}
# Characters 56-62:
let zero = {f = `Int 0} ;; (* fails *)
^^^^^^
Error: This expression has type [> `Int of int ]
but an expression was expected of type [< `Int of int ]
Types for tag `Int are incompatible
# val id : 'a -> 'a = <fun>
val neg : int -> bool -> int * bool = <fun>
# type t = A of int | B of (int * t) list | C of (string * t) list
val transf : (int -> t) -> t -> t = <fun>
val transf_alist : (int -> t) -> ('a * t) list -> ('a * t) list = <fun>
# type t = { f : 'a. ('a list -> int) Lazy.t; }
val l : t = {f = <lazy>}
# type t = { f : 'a. 'a -> unit; }
# - : t = {f = <fun>}
# Characters 19-20:
let f ?x y = y in {f};; (* fail *)
^
Error: This field value has type unit -> unit which is less general than
'a. 'a -> unit
# module Polux :
sig
type 'par t = 'par
val ident : 'a -> 'a
class alias : object method alias : 'a t -> 'a end
val f : < m : 'a. 'a t > -> < m : 'a. 'a >
end
# Exception: Pervasives.Exit.
# Exception: Pervasives.Exit.
# Exception: Pervasives.Exit.
# Characters 16-44:
type 'x t = < f : 'y. 'y t >;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: In the definition of t, type 'y t should be 'x t
# val using_match : bool -> int * ('a -> 'a) = <fun>
# - : ('a -> 'a) * ('b -> 'b) = (<fun>, <fun>)
# - : ('a -> 'a) * ('b -> 'b) = (<fun>, <fun>)
# val n : < m : 'x 'a. ([< `Foo of 'x ] as 'a) -> 'x > = <obj>
# val n : < m : 'x. [< `Foo of 'x ] -> 'x > = <obj>
# Characters 60-130:
object method m : 'x. [< `Foo of 'x] -> 'x = fun x -> assert false end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This expression has type < m : 'x. [< `Foo of 'x ] -> 'x >
but an expression was expected of type
< m : 'a. [< `Foo of int ] -> 'a >
The universal variable 'x would escape its scope
# Characters 83-153:
object method m : 'x. [< `Foo of 'x] -> 'x = fun x -> assert false end;;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This expression has type < m : 'x. [< `Foo of 'x ] -> 'x >
but an expression was expected of type
< m : 'a. [< `Foo of int ] -> 'a >
The universal variable 'x would escape its scope
# Characters 95-98:
if b then x else M.A;;
^^^
Error: This expression has type M.t but an expression was expected of type 'x
The type constructor M.t would escape its scope
#