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|
(* This was reported as a bug in several implementations which failed to detect a
type error. Poly/ML correctly detects it but I'm including this in the regression
set just to make sure we don't accidentally allow it in the future. *)
structure S:
sig
val f: 'a option -> 'a option
end =
struct
val make: unit -> 'a option -> 'a option =
fn () =>
let
val r: 'a option ref = ref NONE
in
fn z => (!r before (r := z))
end
val f = make ()
end
val _ = S.f (SOME 13)
val _ =
case S.f (SOME (fn z => z)) of
NONE => 15
| SOME f => f 17
;
|
