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|
(* TEST
* expect
*)
type 'p pair = 'a * 'b constraint 'p = < left:'a; right:'b>
(* New in 4.11 *)
let error: 'left 'right.
<left:'left; right:'right> pair -> <left:'right; right:'left> pair =
fun (x,y) -> (y,x)
[%%expect{|
type 'c pair = 'a * 'b constraint 'c = < left : 'a; right : 'b >
val error :
< left : 'left; right : 'right > pair ->
< left : 'right; right : 'left > pair = <fun>
|}]
(* Known problem with polymorphic methods *)
let foo :
< m : 'left 'right. <left:'left; right:'right> pair >
-> < m : 'left 'right. <left:'left; right:'right> pair >
= fun x -> x
[%%expect{|
Line 4, characters 11-12:
4 | = fun x -> x
^
Error: This expression has type
< m : 'left 'right. < left : 'left; right : 'right > pair >
but an expression was expected of type
< m : 'left 'right. < left : 'left; right : 'right > pair >
Types for method m are incompatible
|}]
|
