[Caml-list] Module/Functor modelisation

[Caml-list] Module/Functor modelisation

[Johan Baltié]

Hi !

I have a simple functor:

module type Used =
sig 
 type output

 val toto : int -> output -> output
 val tutu : double -> output -> output
end

module type User =
 functor (U : Used) ->
sig

 val toto : int -> U.output -> U.output
 val tutu : double -> U.output -> U.output
end

And User is implemented by two types doing mostly the same things with different
init, and with recursive and/or mutual call in toto an tutu.

I'd like to factorize the shared code, BUT the recursive call prevent me of
doing this. Here an implementation example of the part where the problem lie:

 module User1: User =
   functor (U : Used) ->
 struct
   let toto i output = 
     let val = U.tutu 12.0 output
     in
      tutu 12.0 val

    let rec tutu d output =
       if (d = 11.0) then
          output
       else
          tutu (d -. 1.0) (U.toto 1 output)
 end



 module User2: User =
   functor (U : Used) ->
 struct
   let toto i output = 
     let val = tutu 12.0 output
     in
      U.tutu 12.0 val

    let rec tutu d output =
       if (d = 11.0) then
          output
       else
          let val = tutu (d -. 1.0) output
           in
               U.toto 1 val
 end


Basicly I once do things in a Prefix way, and once in a postfix way.
I would like to call in User toto and tutu function like:

 let toto i data =
   Used.tutu 12.0 data

  let tutu d output =
     User.tutu (d -. 1.0) output

My problem lays here. I cannot now which User.tutu to call. If I try to make a
functor that do take a User module, there is a recursion problem as this functor
will need a User module and the user module will need this functor to be able to
call the helping functions ! It's gaving me headache....

I know this explanation is not really clear, but I tried to simplify my problem
in order to explain it and I fear people won't see any usefullness in my needs. 

Thanks in advance

Ciao

Jo
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Fw: Re: [Caml-list] Module/Functor modelisation

[Johan Baltié]

Uh..
My code was not caml compliant :)
But no that's not my main problem.

I thing i cannot go without giving my real code:

Here is it: 

--------

module type Visitor =
sig
 type output

 val behavior : behavior -> output -> output
 val pattern_action : pattern_action -> output -> output
 val pattern : pattern -> output -> output
 val action : action -> output -> output
 val ident_regex : ident_regex -> output -> output
 val message :  message -> output -> output
 val message_body: message_body -> output -> output
 val declaration :  declaration -> output -> output
 val types : types -> output -> output
 val ident : ident -> output -> output
 val expression : expression -> output -> output
 val litteral : litteral -> output -> output
end

(* Traverser type *)
module type Traverse =
 functor (Av : Visitor) ->
sig
 val behavior : behavior -> Av.output -> Av.output
 val pattern_action : pattern_action -> Av.output -> Av.output
 val pattern : pattern -> Av.output -> Av.output
 val action : action -> Av.output -> Av.output
 val ident_regex : ident_regex -> Av.output -> Av.output
 val message :  message -> Av.output -> Av.output
 val message_body: message_body -> Av.output -> Av.output
 val declaration :  declaration -> Av.output -> Av.output
 val types : types -> Av.output -> Av.output
 val ident : ident -> Av.output -> Av.output
 val expression : expression -> Av.output -> Av.output
 val litteral : litteral -> Av.output -> Av.output
end

(* Traverser implementation *)
module PrefixTraverse =
 functor (Av : Visitor) ->
struct

 let ident i data =
  Av.ident i data

 let rec types t data =
  let output = Av.types t data
  in
   match t with
    | SimpleType(id) ->
       ident id output
    | TypesList(t1, t2) ->
       types t2 (types t1 output)

 let rec ident_regex i data =
  let output = Av.ident_regex i data
  in
   match i with
    | Underscore -> 
       output
    | Ident(id) ->
       ident id output
    | IdentRegexList(id1, id2) ->
       ident_regex id2 (ident_regex id1 output)

 let rec declaration d data =
  let output = Av.declaration d data
  in
   match d with
    | DeclarationConstant(l) ->
       litteral l output
    | DeclarationVariable(t, id) ->
       ident_regex id (types t output)
    | DeclarationList(d1, d2) ->
       declaration d2 (declaration d1 output)

 and pattern p data =
  let output = Av.pattern p data
  and (id1, id2, decl) = p
  in
   declaration decl (ident_regex id2 (ident_regex id1 output))

 and  message m data =
  let output = Av.message m data
  in
   match m with
    | UnansweredMessage(mb) ->
       message_body mb output
    | AnsweredMessage(mb, id) ->
       ident id (message_body mb output)
    | MessageList (m1, m2) ->
       message m2 (message m1 output)

 and message_body m data =
  let output = Av.message_body m data
  in
   match m with
    | NamedMessage(id, e) ->
       expression e (ident id output)
    | AnonymousMessage(e) ->
       expression e output

 and litteral l data =
  let output = Av.litteral l data
  in
   match l with
    | Message(m) ->
       message m output
    | _ ->
       output

 and expression e data =
  let output = Av.expression e data
  in
   match e with
    | ExpressionConstant(l) ->
       litteral l output
    | ExpressionVariable(i) ->
       ident i output
    | ExpressionList(e1, e2) ->
       expression e2 (expression e1 output)

 let action a data =
  let output = Av.action a data
  and (m, e) = a
  in
   expression e (message m output)

 let rec pattern_action p data =
  let output = Av.pattern_action p data
  in 
   match p with
    | PatternAction(pat, act) ->
       action act (pattern pat output)
    | PatternActionList(pa1, pa2) ->
       pattern_action pa2 (pattern_action pa1 output)

 let behavior b data =
  let output = Av.behavior b data
  in
   match b with
    | InheritedBehavior(name, inherited, pas) ->
       pattern_action pas (ident inherited (ident name output))
    | RootedBehavior(name, pas) ->
       pattern_action pas (ident name output)
       
end

(* Traverser implementation *)
module PostfixTraverse =
 functor (Av : Visitor) ->
struct

 let ident i data =
  Av.ident i data

 let rec types t data =
  let output =
   match t with
    | SimpleType(id) ->
       ident id data
    | TypesList(t1, t2) ->
       types t2 (types t1 data)
  in
   Av.types t output

 let rec ident_regex i data =
  let output = 
   match i with
    | Underscore -> 
       data
    | Ident(id) ->
       ident id data
    | IdentRegexList(id1, id2) ->
       ident_regex id2 (ident_regex id1 data)
  in
   Av.ident_regex i output

 let rec declaration d data =
  let output = Av.declaration d data
  in
   match d with
    | DeclarationConstant(l) ->
       litteral l output
    | DeclarationVariable(t, id) ->
       ident_regex id (types t output)
    | DeclarationList(d1, d2) ->
       declaration d2 (declaration d1 output)

 and pattern p data =
  let output = Av.pattern p data
  and (id1, id2, decl) = p
  in
   declaration decl (ident_regex id2 (ident_regex id1 output))

 and  message m data =
  let output = Av.message m data
  in
   match m with
    | UnansweredMessage(mb) ->
       message_body mb output
    | AnsweredMessage(mb, id) ->
       ident id (message_body mb output)
    | MessageList (m1, m2) ->
       message m2 (message m1 output)

 and message_body m data =
  let output = Av.message_body m data
  in
   match m with
    | NamedMessage(id, e) ->
       expression e (ident id output)
    | AnonymousMessage(e) ->
       expression e output

 and litteral l data =
  let output = Av.litteral l data
  in
   match l with
    | Message(m) ->
       message m output
    | _ ->
       output

 and expression e data =
  let output = Av.expression e data
  in
   match e with
    | ExpressionConstant(l) ->
       litteral l output
    | ExpressionVariable(i) ->
       ident i output
    | ExpressionList(e1, e2) ->
       expression e2 (expression e1 output)

 let action a data =
  let output = Av.action a data
  and (m, e) = a
  in
   expression e (message m output)

 let rec pattern_action p data =
  let output = Av.pattern_action p data
  in 
   match p with
    | PatternAction(pat, act) ->
       action act (pattern pat output)
    | PatternActionList(pa1, pa2) ->
       pattern_action pa2 (pattern_action pa1 output)

 let behavior b data =
  let output = Av.behavior b data
  in
   match b with
    | InheritedBehavior(name, inherited, pas) ->
       pattern_action pas (ident inherited (ident name output))
    | RootedBehavior(name, pas) ->
       pattern_action pas (ident name output)
       
end

--------

As I said, my problem is that I'm doing the same job once in a prefix way and
once in a postfix way.
In pattern_action i'd like to have:

"match p with
    | PatternAction(pat, act) ->
       action act (pattern pat output)
    | PatternActionList(pa1, pa2) ->
       pattern_action pa2 (pattern_action pa1 output)"

Factorized from Prefix and Postfix.

Does it enlight my dark explanation ?

> On Wed, Aug 14, 2002 at 08:07:53AM +0100, Johan Baltié wrote:
> > Hi !
> > 
> > I have a simple functor:
> > [..]
> 
> 	I do not know if I have understood your problem but try
> something like that:
> 
>  module type Used =
>  sig
>   type output
> 
>   val toto : int -> output -> output
>   val tutu : float -> output -> output
>  end
> 
>  module type User =
>   functor (U : Used) ->
>  sig
> 
>   val toto : int -> U.output -> U.output
>   val tutu : float -> U.output -> U.output
>  end
> 
>   module User1: User =
>     functor (U : Used) ->
>   struct
>     let rec toto i output =
>       let v = U.tutu 12.0 output
>       in
>        tutu 12.0 v
>      and tutu d output =
>         if (d = 11.0) then
>            output
>         else
>            tutu (d -. 1.0) (U.toto 1 output)
>   end
> 
>   module User2: User =
>     functor (U : Used) ->
>   struct
>     let rec toto i output =
>       let v = tutu 12.0 output
>       in
>        U.tutu 12.0 v
>      and tutu d output =
>         if (d = 11.0) then
>            output
>         else
>            let v = tutu (d -. 1.0) output
>             in
>                 U.toto 1 v
>   end
> 
> -- 
> Yann Régis-Gianas.

Ciao

Jo
------- End of Forwarded Message -------


Ciao

Jo
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Re: [Caml-list] Module/Functor modelisation

[Yann Régis-Gianas]

On Wed, Aug 14, 2002 at 09:58:06AM +0100, Johan Baltié wrote:
> Mon probleme tient effectivement dans l'utilisation d'un autre functor.
> 
> Appellons le GenericTraverse:
> 
> module GenericTraverse =
>  functor (T : Traverse) -> 
> 		  functor (Av: Visitor) -> 
> struct
>  .....
>   let pattern_action p data =
>   match p with
>    | PatternAction(pat, act) ->
>       T.action act (T.pattern pat data)
>    | PatternActionList(pa1, pa2) ->
>       T.pattern_action pa2 (T.pattern_action pa1 data)
> ....
> end
> 
> 
> Le probleme est maintenant comment l'utiliser ???
> 
> module PostfixTraverse = ????
> struct
> 
>  let pattern_action p data =
>   let output = Av.pattern_action p data
>   in 
>     GenericTraverse.pattern_action p output
> end
> 


	Ce que tu es en train de faire, ca s'appelle des modules
mixins et malheuresement Objective Caml ne le gère pas pour le moment.

	Par contre, est-ce que tu ne voudrais pas faire un truc du style:

	module type TraverseWithoutPatternAction =
	sig
	(* ce qui ne dépend pas de pattern_action *)
	end

	module PostfixTraverse (T : TraverseWithoutPatternAction) (Av: Visitor) =
	struct

	let pattern_action p data =
	(* ... *)

	end

	module type TraverseType =
	sig
	
	val pattern_action : (* .. *)

	end

	module FinalTraverse (T : TraverseType) =
	struct

	(* ce qui dépend de pattern action *)

	end
	

-- 
Yann Régis-Gianas.
-------------------
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Re: [Caml-list] Module/Functor modelisation

[Yann Régis-Gianas]

On Wed, Aug 14, 2002 at 10:32:39AM +0100, Johan Baltié wrote:
> Ce n'est malheureusement pas faisable parce qu'il me faudrait le faire pour
> *tous* les types (à l'exception des types feuilles de mon AST, ce qui m'en fait
> 2 en moins) et comme certains types sont mutuellement recursifs ca coince....

	Alors, je ne vois plus de solution.

> 
> En fait il me manque l'extension de module avec module partiellement defini.

	Tu veux dire des modules avec des valeurs différées ? Ce sont
des modules mixins. Allez hop, regarde ces articles pour te faire une
idée de la chose :

http://pauillac.inria.fr/~xleroy/publi/mixins-cbv-esop2002.pdf
ftp://ftp.disi.unige.it/pub/personÅnconaD/DISI-TR-99-05.ps.gz


> Ou alors il y a un moyen de *simuler* ceci, mais je ne vois pas comment

	Malheuresement non, il n'y a pas moyen car le système de
modules tel qu'il est fait ne supporte que les relations d'importations
qui forment un graphe acyclique. Il va falloir que tu continues avec la
méthode du départ ou bien que tu changes de modélisation.

-- 
Yann Régis-Gianas.
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