Using "include" instead of "open" would work, ie. turning your example into:
module Vec_main = struct
type t = { x: int; y: int }
let make x y = {x;y}
let add a b = {x=a.x+b.x; y=a.y+b.y}
end
module Vec = struct
include Vec_main
module Type = struct
include Vec_main
...
end
end
Then:
# let n = Vec.make 2 5;;
val n : Vec.t = {Vec.x = 2; Vec.y = 5}
# open Vec.Type;;
# let m = {x=1;y=2};;
val m : Vec.Type.t = {x = 1; y = 2}
# Vec.add m n;;
- : Vec.t = {Vec.x = 3; Vec.y = 7}
Cheers
--
Vincent Aravantinos - Postdoctoral Fellow, Concordia University, Hardware
Verification Group
On 11/02/2011 03:41 PM, Anthony Tavener wrote:
I've been struggling with this occasionally...
I'm using nested modules to "open" access to select features of a
module. My problem is I can't find a way to *expose* types in the
parent module through such nested modules.
A simplified example of what I'm looking at:
module Vec = struct
type t = { x: int; y: int }
let make x y = {x;y}
let add a b = {x=a.x+b.x; y=a.y+b.y}
module Type =
(* something which has type t = Vec.t,
* with exposed structure when "open"ed.
* Also note that Vec is not really an
* explicit module like this; instead it
* is implemented in vec.ml <http://vec.ml> *)
end
Example usage...
let n = Vec.make 2 5
open Vec.Type
let m = {x=1;y=2}
Vec.add m n
To date, I've defined the type in the Type submodule, which is then
used by the parent module. The unsatisfactory quality of this is that
Vec.Type.t is the "true" type. Ideally the concrete type would live at
Vec.t, with "open Vec.Type" bringing the fields of the type into scope.
As background, here are examples of opening different features of the
Vec module:
let c = Vec.add a b
open Vec.Prefixed
let c = vadd a b
open Vec.Ops
let c = a +| b
open Vec.Type
let c = Vec.add a {x;y;z=0.}
Apologies if this is really beginner-list material. It's minor, but
has been bugging me.
Thank-you for looking,
Tony
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