 +      { mkmty(Pmty_functor(mkrhs "*" 2, mkmty(Pmty_signature []), $5)) }
    | module_type WITH with_constraints
        { mkmty(Pmty_with($1, List.rev $3)) }
-   | MODULE TYPE OF module_expr
-@@ -679,6 +688,8 @@
+   | MODULE TYPE OF module_expr %prec below_LBRACKETAT
+@@ -725,6 +734,8 @@
        { $2 }
    | LPAREN UIDENT COLON module_type RPAREN module_declaration
        { mkmty(Pmty_functor(mkrhs $2 2, $4, $6)) }

   | With_need_typeconstr ->
       fprintf ppf
         "Only type constructors with identical parameters can be substituted."
@@ -1446,3 +1457,5 @@
         "The type %a in this module cannot be exported.@ " longident lid;
       fprintf ppf
         "Its type contains local dependencies:@ %a" type_expr ty
+  | Apply_impure ->
+      fprintf ppf "This functor is impure. It can only be applied to ()"
Index: typing/typemod.mli
===================================================================
--- typing/typemod.mli	(revision 13286)
+++ typing/typemod.mli	(working copy)
@@ -60,6 +60,7 @@
   | Not_a_packed_module of type_expr
   | Incomplete_packed_module of type_expr
   | Scoping_pack of Longident.t * type_expr
+  | Apply_impure
 
 exception Error of Location.t * error
 
Index: typing/oprint.ml
===================================================================
--- typing/oprint.ml	(revision 13286)
+++ typing/oprint.ml	(working copy)
@@ -343,6 +343,8 @@
 let rec print_out_module_type ppf =
   function
     Omty_abstract -> ()
+  | Omty_functor ("*", _, mty_res) ->
+      fprintf ppf "@[<2>functor@ () ->@ %a@]" print_out_module_type mty_res
   | Omty_functor (name, mty_arg, mty_res) ->
       fprintf ppf "@[<2>functor@ (%s : %a) ->@ %a@]" name
         print_out_module_type mty_arg print_out_module_type mty_res
Index: typing/includemod.ml
===================================================================
--- typing/includemod.ml	(revision 13286)
+++ typing/includemod.ml	(working copy)
@@ -35,6 +35,7 @@
       Ident.t * class_declaration * class_declaration *
       Ctype.class_match_failure list
   | Unbound_modtype_path of Path.t
+  | Impure_functor
 
 type pos =
     Module of Ident.t | Modtype of Ident.t | Arg of Ident.t | Body of Ident.t
@@ -153,6 +154,8 @@
   | (Mty_signature sig1, Mty_signature sig2) ->
       signatures env cxt subst sig1 sig2
   | (Mty_functor(param1, arg1, res1), Mty_functor(param2, arg2, res2)) ->
+      if Ident.name param1 = "*" && Ident.name param2 <> "*" then
+        raise (Error [cxt, Impure_functor]);
       let arg2' = Subst.modtype subst arg2 in
       let cc_arg = modtypes env (Arg param1::cxt) Subst.identity arg2' arg1 in
       let cc_res =
@@ -404,6 +407,8 @@
       Includeclass.report_error reason
   | Unbound_modtype_path path ->
       fprintf ppf "Unbound module type %a" Printtyp.path path
+  | Impure_functor ->
+      fprintf ppf "An impure functor cannot be made applicative"
 
 let rec context ppf = function
     Module id :: rem ->
Index: typing/includemod.mli
===================================================================
--- typing/includemod.mli	(revision 13286)
+++ typing/includemod.mli	(working copy)
@@ -40,6 +40,7 @@
       Ident.t * class_declaration * class_declaration *
       Ctype.class_match_failure list
   | Unbound_modtype_path of Path.t
+  | Impure_functor
 
 type pos =
     Module of Ident.t | Modtype of Ident.t | Arg of Ident.t | Body of Ident.t
Index: typing/mtype.ml
===================================================================
--- typing/mtype.ml	(revision 13286)
+++ typing/mtype.ml	(working copy)
@@ -34,7 +34,8 @@
   match scrape env mty with
     Mty_signature sg ->
       Mty_signature(strengthen_sig env sg p)
-  | Mty_functor(param, arg, res) when !Clflags.applicative_functors ->
+  | Mty_functor(param, arg, res)
+    when !Clflags.applicative_functors && Ident.name param <> "*" ->
       Mty_functor(param, arg, strengthen env res (Papply(p, Pident param)))
   | mty ->
       mty

 ;
 module_rec_declarations:
     module_rec_declaration                              { [$1] }
Index: parsing/pprintast.ml
===================================================================
--- parsing/pprintast.ml	(revision 14285)
+++ parsing/pprintast.ml	(working copy)
@@ -834,6 +834,8 @@
     | Pmty_signature (s) ->
         pp f "@[<hv0>@[<hv2>sig@ %a@]@ end@]" (* "@[<hov>sig@ %a@ end@]" *)
           (self#list self#signature_item  ) s (* FIXME wrong indentation*)
+    | Pmty_functor ({txt="*"}, mt1, mt2) ->
+        pp f "@[<hov2>functor () ->@ %a@]" self#module_type mt2 
     | Pmty_functor (s, mt1, mt2) ->
         pp f "@[<hov2>functor@ (%s@ :@ %a)@ ->@ %a@]" s.txt
           self#module_type mt1  self#module_type mt2
@@ -940,6 +942,8 @@
           self#module_type mt
     | Pmod_ident (li) ->
         pp f "%a" self#longident_loc li;
+    | Pmod_functor ({txt="*"}, mt, me) ->
+        pp f "functor ()@;->@;%a" self#module_expr me
     | Pmod_functor (s, mt, me) ->
         pp f "functor@ (%s@ :@ %a)@;->@;%a"
           s.txt  self#module_type mt  self#module_expr me
@@ -1025,7 +1029,8 @@
     | Pstr_module x ->
         let rec module_helper me = match me.pmod_desc with
         | Pmod_functor(s,mt,me) ->
-            pp f "(%s:%a)"  s.txt  self#module_type mt ;
+            if s.txt = "*" then pp f "()"
+            else pp f "(%s:%a)"  s.txt  self#module_type mt ;
             module_helper me
         | _ -> me in
         pp f "@[<hov2>module %s%a@]"
Index: typing/includemod.ml
===================================================================
--- typing/includemod.ml	(revision 14285)
+++ typing/includemod.ml	(working copy)
@@ -35,6 +35,7 @@
       Ident.t * class_declaration * class_declaration *
       Ctype.class_match_failure list
   | Unbound_modtype_path of Path.t
+  | Impure_functor
 
 type pos =
     Module of Ident.t | Modtype of Ident.t | Arg of Ident.t | Body of Ident.t
@@ -165,6 +166,8 @@
   | (Mty_signature sig1, Mty_signature sig2) ->
       signatures env cxt subst sig1 sig2
   | (Mty_functor(param1, arg1, res1), Mty_functor(param2, arg2, res2)) ->
+      if Ident.name param1 = "*" && Ident.name param2 <> "*" then
+        raise (Error [cxt, env, Impure_functor]);
       let arg2' = Subst.modtype subst arg2 in
       let cc_arg = modtypes env (Arg param1::cxt) Subst.identity arg2' arg1 in
       let cc_res =
@@ -422,6 +425,8 @@
       Includeclass.report_error reason
   | Unbound_modtype_path path ->
       fprintf ppf "Unbound module type %a" Printtyp.path path
+  | Impure_functor ->
+      fprintf ppf "An impure functor cannot be made applicative"
 
 let rec context ppf = function
     Module id :: rem ->
Index: typing/includemod.mli
===================================================================
--- typing/includemod.mli	(revision 14285)
+++ typing/includemod.mli	(working copy)
@@ -40,6 +40,7 @@
       Ident.t * class_declaration * class_declaration *
       Ctype.class_match_failure list
   | Unbound_modtype_path of Path.t
+  | Impure_functor
 
 type pos =
     Module of Ident.t | Modtype of Ident.t | Arg of Ident.t | Body of Ident.t
Index: typing/mtype.ml
===================================================================
--- typing/mtype.ml	(revision 14285)
+++ typing/mtype.ml	(working copy)
@@ -34,7 +34,8 @@
   match scrape env mty with
     Mty_signature sg ->
       Mty_signature(strengthen_sig env sg p)
-  | Mty_functor(param, arg, res) when !Clflags.applicative_functors ->
+  | Mty_functor(param, arg, res)
+    when !Clflags.applicative_functors && Ident.name param <> "*" ->
       Mty_functor(param, arg, strengthen env res (Papply(p, Pident param)))
   | mty ->
       mty
Index: typing/oprint.ml
===================================================================
--- typing/oprint.ml	(revision 14285)
+++ typing/oprint.ml	(working copy)
@@ -344,6 +344,8 @@
 let rec print_out_module_type ppf =
   function
     Omty_abstract -> ()
+  | Omty_functor ("*", _, mty_res) ->
+      fprintf ppf "@[<2>functor@ () ->@ %a@]" print_out_module_type mty_res
   | Omty_functor (name, mty_arg, mty_res) ->
       fprintf ppf "@[<2>functor@ (%s : %a) ->@ %a@]" name
         print_out_module_type mty_arg print_out_module_type mty_res
Index: typing/typemod.ml
===================================================================
--- typing/typemod.ml	(revision 14285)
+++ typing/typemod.ml	(working copy)
@@ -39,6 +39,7 @@
   | Scoping_pack of Longident.t * type_expr
   | Extension of string
   | Recursive_module_require_explicit_type
+  | Apply_impure
 
 exception Error of Location.t * Env.t * error
 
@@ -950,8 +951,10 @@
            mod_loc = smod.pmod_loc }
   | Pmod_functor(name, smty, sbody) ->
       let mty = transl_modtype env smty in
