Hi,
replacing :
module rec A1 : AA
= struct
type q = ASet.t
type t = string
with :
module rec A1 : AA with type q = ASet.t, type t = string
should be okay. Shouldn't it ?
On Wed, Mar 18, 2009 at 1:08 PM, Hugo Ferreira <h...@inescporto.pt> wrote:
> Hello,
>
> I hope this is not a beginners questions.
> I am trying to reuse code via functors,
> however I am getting the following error:
>
> Cannot safely evaluate the definition of the recursively-defined module
> (refers to "AA.empty" when implemented as a constant value)
>
> I circumvented the problem by not using a
> constant value but a function instead. As I
> understand it this may cause run-time errors.
> My question is: is their any way to make the
> following example work.
>
> Specifically, for the example below is their
> any way of indicating to the compiler that
> AA.q = ASet.t ?
>
> TIA,
> Hugo F.
>
> module type AA =
> sig
> type q
> type t = string
>
> val compare: t -> t -> int
> val add: t -> q -> q
> val empty: unit -> q
> end
>
> module rec A1 : AA
> = struct
> type q = ASet.t
> type t = string
>
> let compare s1 s2 = Pervasives.compare s1 s2
> let add e s = ASet.add e s
> let empty _ = ASet.empty
> end
> and ASet : Set.S with type elt = A1.t
> = Set.Make(A1)
>
> module type Wrap_A =
> sig
> type t
> type q
>
> val init: q
> val add: t -> q -> q
> end
>
> module Make_A (An_A : AA) : Wrap_A
> =
> struct
> type t = An_A.t
> type q = An_A.q
>
> (*let init = ASet.empty*)
> let init = An_A.empty ()
> let add t q = An_A.add t q
> end
>
> module Wrap_A1 = Make_A( A1 )
>
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--
Alp Mestan
In charge of the C++ section on Developpez.com.
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