Re: [Caml-list] Inter-module dependences [solved]

[Damien Bobillot <damien.bobillot@m4x.org>]

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Le 15 juin 05 à 17:39, Remi Vanicat a écrit :

> 2005/6/15, Damien Bobillot <damien.bobillot@m4x.org>:
>
>> I'm defining a graph structure compatible with the ocamlgraph  
>> library.
>>
>> I want to be able to access all neighbors and edge to neighbors of a
>> vertex in 0(1), so I think I need to store the outgoing edge list of
>> each vertex in the vertex structure. I also need to be able to access
>> the source and destination of an edge in 0(1), so I store these
>> vertex in the edge structure.
>>
>> A standard Caml will be :
>>
>> type vertex = {
>>      label : int;
>>      out_edges : edge list;
>>      ...
>> } and edge = {
>>      label : int;
>>      src : vertex;
>>      dst : vertex;
>>      ...
>> }
>>
>> However, in ocamlgraph, the vertex and edge type must be defined by
>> modules of signatures (and I cannot modify it) :
>>
>> module type VERTEX = sig
>>      type t
>>      type label
>>      val create : label -> t
>>      val label : t -> label
>> end
>> module type EDGE = sig
>>      type t
>>      type label
>>      type vertex
>>      val create : vertex -> label -> vertex -> t
>>      val label : t -> label
>>      val src : t -> vertex
>>      val dst : t -> vertex
>> end
>>
>
> [...]
>
>
>> It works fine, but it doesn't respond to my problem : I want that V
>> use a type from E and at the same time E use a type of V.
>
> Why don't you do something like what follow ?
>
> type vertex = {
>       label : int;
>       out_edges : edge list;
>       ...
>  } and edge = {
>       label : int;
>       src : vertex;
>       dst : vertex;
>       ...
>  }
>
> module MyVertex : (VERTEX with t=vertex and label=int)=
> struct
>   type t=vertex
>    ....
> end
>
> module MyEdge : (EDGE with t=edge ...) =
> struct
>   type t = edge
>   ....
> end
>
> It should work with no problem.

Yes, it works !!!

Modules are powerful, but as every powerful things, it's hard to use  
without a manual... (and I didn't found a good manual on the web, if  
you know one I'll be interested).

Thank you very much

-- 
Damien Bobillot


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