From: Aaron Bohannon <bohannon@cis.upenn.edu>
To: Caml List <caml-list@inria.fr>
Subject: exceptions in recursive modules
Date: Mon, 06 Dec 2004 21:26:51 -0500 [thread overview]
Message-ID: <41B514EB.7030707@cis.upenn.edu> (raw)
I was trying to use a recursive module but was getting unexpected
"Undefined_recursive_modules" exceptions. After a long debugging
session, I discovered the source of my problem to be exception
declarations in the module. I don't intuitively understand why they
cause a problem, and as I cannot find documentation of the behavior, I
am wondering if it might be a bug.
Here is the example. This is essentially the example in the manual, but
I have added an exception to the module:
module rec A : sig
type t = Leaf of int | Node of ASet.t
exception Fail
val compare : t -> t -> int
end = struct
type t = Leaf of int | Node of ASet.t
exception Fail
let rec compare = (* suitable definition *)
end
and ASet : Set.S with type elt = A.t = Set.Make(A)
Then we can try to use it:
# let x = A.Leaf(3);;
val x : A.t = A.Leaf 3
# let s = ASet.add x ASet.empty;;
val s : ASet.t = <abstr>
# let s' = ASet.add x s;;
Exception: Undefined_recursive_module ("recmodtest.ml", 6, 6).
If we remove the "exception Fail" from the signature, everything works
just fine. Is this behavior correct? (I am using OCaml 3.08.1)
Aaron
--
Aaron Bohannon
http://www.cis.upenn.edu/~bohannon/
next reply other threads:[~2004-12-07 2:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-07 2:26 Aaron Bohannon [this message]
2004-12-07 6:58 ` [Caml-list] " Tom Hirschowitz
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