[Caml-list] Re: Type unification problem

[Richard Jones <rich@annexia.org>]

On Wed, Jun 30, 2004 at 01:16:25PM +0100, rich wrote:
> Why this error (below)?  I can "fix" it by adding quite a lot of
> explicit types (I need one on every function which uses the
> Dbi.connection parameter).  Is there a simpler way to fix it?

[Sorry, there was an actual error in the last posting.  This is the
real error:]

File "contact.ml", line 81, characters 25-28:
This expression has type
  Apache.Request.t ->
  Cgi.cgi ->
  (< prepare_cached : string ->
                      (< execute : Dbi.sql_t list -> unit;
                         map : ([> `String of 'c ] list -> 'c) -> string list;
                         .. >
                       as 'b);
     .. >
   as 'a) ->
  int -> string -> 'd -> unit
but is here used with type
  Apache.Request.t ->
  Cgi.cgi -> Dbi.connection -> int -> string -> Ewp.login_t -> unit
Type 'a is not compatible with type
  Dbi.connection =
    < close : unit -> unit; closed : bool; commit : unit -> unit;
      database : string; database_type : string; debug : bool;
      ex : string -> Dbi.sql_t list -> Dbi.statement; host : string option;
      id : int; password : string option; ping : unit -> bool;
      port : string option; prepare : string -> Dbi.statement;
      prepare_cached : string -> Dbi.statement;
      register_postrollback : (unit -> unit) -> Dbi.postrollback_handle;
      register_precommit : (unit -> unit) -> Dbi.precommit_handle;
      rollback : unit -> unit; set_debug : bool -> unit;
      unregister_postrollback : Dbi.postrollback_handle -> unit;
      unregister_precommit : Dbi.precommit_handle -> unit;
      user : string option > 
Type 'b is not compatible with type
  Dbi.statement =
    < connection : Dbi.connection; execute : Dbi.sql_t list -> unit;
      fetch1 : unit -> Dbi.sql_t list;
      fetch1hash : unit -> (string * Dbi.sql_t) list;
      fetch1int : unit -> int; fetch1string : unit -> string;
      fetchall : unit -> Dbi.sql_t list list; finish : unit -> unit;
      fold_left : 'e. ('e -> Dbi.sql_t list -> 'e) -> 'e -> 'e;
      fold_right : 'f. (Dbi.sql_t list -> 'f -> 'f) -> 'f -> 'f;
      iter : (Dbi.sql_t list -> unit) -> unit;
      map : 'g. (Dbi.sql_t list -> 'g) -> 'g list; names : string list;
      serial : string -> int > 
make: *** [contact.cmo] Error 2


-- 
Richard Jones. http://www.annexia.org/ http://www.j-london.com/
Merjis Ltd. http://www.merjis.com/ - improving website return on investment
Learning Objective CAML for C, C++, Perl and Java programmers:
http://www.merjis.com/richj/computers/ocaml/tutorial/

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