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File "pr3968_bad.ml", lines 20-29, characters 0-3:
20 | object
21 | val l = e1
22 | val r = e2
23 | method eval env =
24 | match l with
25 | | `Abs(var,body) ->
26 | Hashtbl.add env var r;
27 | body
28 | | _ -> `App(l,r);
29 | end
Error: The class type
object
val l :
[ `Abs of string * ([> `App of 'a * exp ] as 'b)
| `App of expr * expr ] as 'a
val r : exp
method eval : (string, exp) Hashtbl.t -> 'b
end
is not matched by the class type exp
The class type
object
val l :
[ `Abs of string * ([> `App of 'a * exp ] as 'b)
| `App of expr * expr ] as 'a
val r : exp
method eval : (string, exp) Hashtbl.t -> 'b
end
is not matched by the class type
object method eval : (string, exp) Hashtbl.t -> expr end
The method eval has type
(string, exp) Hashtbl.t ->
([> `App of [ `Abs of string * 'a | `App of expr * expr ] * exp ]
as 'a)
but is expected to have type (string, exp) Hashtbl.t -> expr
Type
[> `App of [ `Abs of string * 'a | `App of expr * expr ] * exp ]
as 'a
is not compatible with type
expr = [ `Abs of string * expr | `App of expr * expr ]
Type exp = < eval : (string, exp) Hashtbl.t -> expr >
is not compatible with type
expr = [ `Abs of string * expr | `App of expr * expr ]
Types for tag `App are incompatible
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