Dear ocaml-list,
the following code does not type check:

type foo = {bar : 'a. 'a -> 'a}
let a : int -> int = fun x -> x
let baz = {bar = Obj.magic a}

with the error

Error: This field value has type 'a -> 'a which is less general than
         'b. 'b -> 'b


my question is: how could I use obj.magic to get a polymorphic type?


Jacques