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|
(* TEST
* expect
*)
module Element : sig
type +'a t
val from_a : [`A] t -> unit
val from_ab : [< `A | `B] t -> unit
val to_a : unit -> [`A] t
val to_ab : unit -> [< `A | `B] t
end = struct
type +'a t
let from_a x = assert false
let from_ab x = assert false
let to_a x = assert false
let to_ab x = assert false
end ;;
[%%expect{|
module Element :
sig
type +'a t
val from_a : [ `A ] t -> unit
val from_ab : [< `A | `B ] t -> unit
val to_a : unit -> [ `A ] t
val to_ab : unit -> [< `A | `B ] t
end
|}];;
let f x =
Element.from_a x;
Element.from_ab x;
match [] with
| _::_ -> (x :> [`A | `C] Element.t)
;;
[%%expect{|
Lines 4-5, characters 2-38:
4 | ..match [] with
5 | | _::_ -> (x :> [`A | `C] Element.t)
Warning 8 [partial-match]: this pattern-matching is not exhaustive.
Here is an example of a case that is not matched:
[]
val f : [ `A ] Element.t -> [ `A | `C ] Element.t = <fun>
|}];;
type _ t = T : 'a -> 'a t
let f x =
Element.from_a x;
Element.from_ab x;
match T () with
| T _ -> (x :> [`A | `C] Element.t)
;;
[%%expect{|
type _ t = T : 'a -> 'a t
val f : [ `A ] Element.t -> [ `A | `C ] Element.t = <fun>
|}];;
let f () =
let open Element in
let x = if true then to_ab () else to_a () in
(x :> [ `A | `C ] Element.t)
;;
[%%expect{|
val f : unit -> [ `A | `C ] Element.t = <fun>
|}];;
let f () =
let open Element in
let x = if true then to_a () else to_ab () in
(x :> [ `A | `C ] Element.t)
;;
[%%expect{|
val f : unit -> [ `A | `C ] Element.t = <fun>
|}];;
|
