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|
(* TEST
* expect
*)
let f = function
| ([] : int list) as x -> x
| _ :: _ -> assert false;;
[%%expect{|
val f : int list -> int list = <fun>
|}]
let f =
let f' = function
| ([] : 'a list) as x -> x
| _ :: _ -> assert false
in
f', f';;
[%%expect{|
val f : ('a list -> 'a list) * ('a list -> 'a list) = (<fun>, <fun>)
|}]
let f =
let f' = function
| ([] : _ list) as x -> x
| _ :: _ -> assert false
in
f', f';;
[%%expect{|
val f : ('a list -> 'b list) * ('c list -> 'd list) = (<fun>, <fun>)
|}]
let f =
let f' (type a) = function
| ([] : a list) as x -> x
| _ :: _ -> assert false
in
f', f';;
[%%expect{|
val f : ('a list -> 'a list) * ('b list -> 'b list) = (<fun>, <fun>)
|}]
type t = [ `A | `B ];;
[%%expect{|
type t = [ `A | `B ]
|}]
let f = function `A as x -> x | `B -> `A;;
[%%expect{|
val f : [< `A | `B ] -> [> `A ] = <fun>
|}]
let f = function (`A : t) as x -> x | `B -> `A;;
[%%expect{|
val f : t -> t = <fun>
|}]
let f : t -> _ = function `A as x -> x | `B -> `A;;
[%%expect{|
val f : t -> [> `A ] = <fun>
|}]
let f = function
| (`A : t) as x ->
(* This should be flagged as non-exhaustive: because of the constraint [x]
is of type [t]. *)
begin match x with
| `A -> ()
end
| `B -> ();;
[%%expect{|
Lines 5-7, characters 4-7:
5 | ....begin match x with
6 | | `A -> ()
7 | end
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
`B
val f : t -> unit = <fun>
|}]
let f = function
| (`A : t) as x ->
begin match x with
| `A -> ()
| `B -> ()
end
| `B -> ();;
[%%expect{|
val f : t -> unit = <fun>
|}]
let f = function
| (`A : t) as x ->
begin match x with
| `A -> ()
| `B -> ()
| `C -> ()
end
| `B -> ();;
[%%expect{|
Line 6, characters 6-8:
6 | | `C -> ()
^^
Error: This pattern matches values of type [? `C ]
but a pattern was expected which matches values of type t
The second variant type does not allow tag(s) `C
|}]
let f = function (`A, _ : _ * int) as x -> x;;
[%%expect{|
val f : [< `A ] * int -> [> `A ] * int = <fun>
|}]
(* Make sure *all* the constraints are respected: *)
let f = function
| ((`A : _) : t) as x ->
(* This should be flagged as non-exhaustive: because of the constraint [x]
is of type [t]. *)
begin match x with
| `A -> ()
end
| `B -> ();;
[%%expect{|
Lines 5-7, characters 4-7:
5 | ....begin match x with
6 | | `A -> ()
7 | end
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
`B
val f : t -> unit = <fun>
|}]
let f = function
| ((`A : t) : _) as x ->
(* This should be flagged as non-exhaustive: because of the constraint [x]
is of type [t]. *)
begin match x with
| `A -> ()
end
| `B -> ();;
[%%expect{|
Lines 5-7, characters 4-7:
5 | ....begin match x with
6 | | `A -> ()
7 | end
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
`B
val f : t -> unit = <fun>
|}]
|
