Module inside an object - ocaml

Question

I would like to define a parameterized module inside an object by the type of this object.
I have two module interlocked :
(* Parameters*)
module type A = sig
type agent
type intern_agent = { i : agent}
val create : agent -> intern_agent
end
module type E = sig
type event
end
module type StateType = sig
type agent
type event
type state_t = {
mutable name : string;
mutable parentstate : state_t option;
}
end
module State (A : A) (E : E) = struct
type agent = A.agent
type event = E.event
type state_t = {
mutable name : string;
mutable parentstate : state_t option;
}
(*...*)
end
module Agent (S : StateType) =
struct
type agent = S.agent
type event = S.event
type state_t = S.state_t
type agent_t = {
mutable agent : agent ;
}
let create a1 = {
agent = a1;
}
end
(* An implementation of E*)
type event1 = Event1 | Event2;;
module E = struct type event = event1 end;;
What I would like to do is something like that (which is syntacticly incorrect but represents what I would like to do) :
class character = object (self :'self)
val mutable position = (0,0)
val agent =
let A = (module Ag = struct
type agent = 'self
type intern_agent = { i : agent}
let create a = { i = a }
end)
in
let Ag = (module Agent(State(A)(E)) ) in
Ag.create self
method getPosition = position
end;;
How can I write this to be able to define a value which is an Agent parametrized by itself ?
Thank you

Answer 1

Syntactically correct version of a character class definition is
class character = object (self :'self)
val mutable position = (0,0)
val agent =
let module A = struct
type agent = character
type intern_agent = { i : agent}
let create a = { i = a }
end in
let module Ag = Agent(State(A)(E)) in
Ag.create self
method getPosition = position
end
Although, it wont compile, since agent_t will escape the scope of the value agent definition. Indeed, you're asking a compiler to allow you to return a value from a function that has type local to the function.
I wish I can give you some advice on how to redesign your code, but I need more information about your intentions.