Remove function$ entirely.

Author: cristianoc

compiler/frontend/ast_core_type.ml

@@ -156,7 +156,7 @@ let mk_fn_type (new_arg_types_ty : param_type list) (result : t) : t =
 let list_of_arrow (ty : t) : t * param_type list =
   let rec aux (ty : t) acc =
     match ty.ptyp_desc with
-    | Ptyp_arrow (label, t1, t2, _) ->
+    | Ptyp_arrow (label, t1, t2, arity) when arity = None || acc = [] ->
       aux t2
         (({label; ty = t1; attr = ty.ptyp_attributes; loc = ty.ptyp_loc}
            : param_type)

compiler/frontend/ast_derive_js_mapper.ml

@@ -130,7 +130,7 @@ let app1 = Ast_compatible.app1
 let app2 = Ast_compatible.app2
 
 let ( ->~ ) a b =
-  Ast_uncurried.uncurried_type ~loc:Location.none ~arity:1
+  Ast_uncurried.uncurried_type ~arity:1
     (Ast_compatible.arrow ~arity:(Some 1) a b)
 
 let raise_when_not_found_ident =
@@ -295,7 +295,7 @@ let init () =
               let pat_from_js = {Asttypes.loc; txt = from_js} in
               let to_js_type result =
                 Ast_comb.single_non_rec_val pat_to_js
-                  (Ast_uncurried.uncurried_type ~loc:Location.none ~arity:1
+                  (Ast_uncurried.uncurried_type ~arity:1
                      (Ast_compatible.arrow ~arity:(Some 1) core_type result))
               in
               let new_type, new_tdcl =

compiler/frontend/ast_derive_projector.ml

@@ -120,9 +120,8 @@ let init () =
             Ext_list.flat_map tdcls handle_tdcl);
         signature_gen =
           (fun (tdcls : Parsetree.type_declaration list) _explict_nonrec ->
-            let handle_uncurried_type_tranform ~loc ~arity t =
-              if arity > 0 then Ast_uncurried.uncurried_type ~loc ~arity t
-              else t
+            let handle_uncurried_type_tranform ~arity t =
+              if arity > 0 then Ast_uncurried.uncurried_type ~arity t else t
             in
             let handle_tdcl tdcl =
               let core_type =
@@ -142,8 +141,7 @@ let init () =
                     Ast_comb.single_non_rec_val ?attrs:gentype_attrs pld_name
                       (Ast_compatible.arrow ~arity:None core_type pld_type
                       (*arity will alwys be 1 since these are single param functions*)
-                      |> handle_uncurried_type_tranform ~arity:1
-                           ~loc:pld_name.loc))
+                      |> handle_uncurried_type_tranform ~arity:1))
               | Ptype_variant constructor_declarations ->
                 Ext_list.map constructor_declarations
                   (fun
@@ -170,7 +168,7 @@ let init () =
                       {loc; txt = Ext_string.uncapitalize_ascii con_name}
                       (Ext_list.fold_right pcd_args annotate_type (fun x acc ->
                            Ast_compatible.arrow ~arity:None x acc)
-                      |> handle_uncurried_type_tranform ~arity ~loc))
+                      |> handle_uncurried_type_tranform ~arity))
               | Ptype_open | Ptype_abstract ->
                 Ast_derive_util.not_applicable tdcl.ptype_loc deriving_name;
                 []

compiler/frontend/ast_exp_handle_external.ml

@@ -133,7 +133,7 @@ let handle_ffi ~loc ~payload =
       match !is_function with
       | Some arity ->
         let type_ =
-          Ast_uncurried.uncurried_type ~loc
+          Ast_uncurried.uncurried_type
             ~arity:(if arity = 0 then 1 else arity)
             (arrow ~arity)
         in

compiler/frontend/ast_external_process.ml

@@ -938,7 +938,7 @@ let handle_attributes (loc : Bs_loc.t) (type_annotation : Parsetree.core_type)
     | {ptyp_desc = Ptyp_arrow (_, _, _, Some _); _} as t ->
       ( t,
         fun ~arity (x : Parsetree.core_type) ->
-          Ast_uncurried.uncurried_type ~loc ~arity x )
+          Ast_uncurried.uncurried_type ~arity x )
     | _ -> (type_annotation, fun ~arity:_ x -> x)
   in
   let result_type, arg_types_ty =

compiler/frontend/ast_typ_uncurry.ml

@@ -66,5 +66,5 @@ let to_uncurry_type loc (mapper : Bs_ast_mapper.mapper)
     | _ -> assert false
   in
   match arity with
-  | Some arity -> Ast_uncurried.uncurried_type ~loc ~arity fn_type
+  | Some arity -> Ast_uncurried.uncurried_type ~arity fn_type
   | None -> assert false

compiler/gentype/TranslateCoreType.ml

@@ -52,7 +52,8 @@ let rec translate_arrow_type ~config ~type_vars_gen
     ~no_function_return_dependencies ~type_env ~rev_arg_deps ~rev_args
     (core_type : Typedtree.core_type) =
   match core_type.ctyp_desc with
-  | Ttyp_arrow (Nolabel, core_type1, core_type2, _) ->
+  | Ttyp_arrow (Nolabel, core_type1, core_type2, arity)
+    when arity = None || rev_args = [] ->
     let {dependencies; type_} =
       core_type1 |> fun __x ->
       translateCoreType_ ~config ~type_vars_gen ~type_env __x
@@ -63,7 +64,8 @@ let rec translate_arrow_type ~config ~type_vars_gen
          ~no_function_return_dependencies ~type_env ~rev_arg_deps:next_rev_deps
          ~rev_args:((Nolabel, type_) :: rev_args)
   | Ttyp_arrow
-      (((Labelled lbl | Optional lbl) as label), core_type1, core_type2, _) -> (
+      (((Labelled lbl | Optional lbl) as label), core_type1, core_type2, arity)
+    when arity = None || rev_args = [] -> (
     let as_label =
       match core_type.ctyp_attributes |> Annotation.get_gentype_as_renaming with
       | Some s -> s

compiler/gentype/TranslateTypeExprFromTypes.ml

@@ -268,7 +268,8 @@ let rec translate_arrow_type ~config ~type_vars_gen ~type_env ~rev_arg_deps
   | Tlink t ->
     translate_arrow_type ~config ~type_vars_gen ~type_env ~rev_arg_deps
       ~rev_args t
-  | Tarrow (Nolabel, type_expr1, type_expr2, _, _) ->
+  | Tarrow (Nolabel, type_expr1, type_expr2, _, arity)
+    when arity = None || rev_args = [] ->
     let {dependencies; type_} =
       type_expr1 |> fun __x ->
       translateTypeExprFromTypes_ ~config ~type_vars_gen ~type_env __x
@@ -279,8 +280,12 @@ let rec translate_arrow_type ~config ~type_vars_gen ~type_env ~rev_arg_deps
          ~rev_arg_deps:next_rev_deps
          ~rev_args:((Nolabel, type_) :: rev_args)
   | Tarrow
-      (((Labelled lbl | Optional lbl) as label), type_expr1, type_expr2, _, _)
-    -> (
+      ( ((Labelled lbl | Optional lbl) as label),
+        type_expr1,
+        type_expr2,
+        _,
+        arity )
+    when arity = None || rev_args = [] -> (
     match type_expr1 |> remove_option ~label with
     | None ->
       let {dependencies; type_ = type1} =

compiler/ml/ast_mapper_from0.ml

@@ -120,10 +120,7 @@ module T = struct
           | _ -> assert false
         in
         let arity = arity_from_type t_arity in
-        let fun_t =
-          {fun_t with ptyp_desc = Ptyp_arrow (lbl, t1, t2, Some arity)}
-        in
-        {typ0 with ptyp_desc = Ptyp_constr (lid, [fun_t])}
+        {fun_t with ptyp_desc = Ptyp_arrow (lbl, t1, t2, Some arity)}
       | _ -> typ0)
     | Ptyp_object (l, o) ->
       object_ ~loc ~attrs (List.map (object_field sub) l) o

compiler/ml/ast_mapper_to0.ml

@@ -98,20 +98,21 @@ module T = struct
     match desc with
     | Ptyp_any -> any ~loc ~attrs ()
     | Ptyp_var s -> var ~loc ~attrs s
-    | Ptyp_arrow (lab, t1, t2, _) ->
-      arrow ~loc ~attrs lab (sub.typ sub t1) (sub.typ sub t2)
+    | Ptyp_arrow (lab, t1, t2, arity) -> (
+      let typ0 = arrow ~loc ~attrs lab (sub.typ sub t1) (sub.typ sub t2) in
+      match arity with
+      | None -> typ0
+      | Some arity ->
+        let arity_string = "Has_arity" ^ string_of_int arity in
+        let arity_type =
+          Ast_helper0.Typ.variant ~loc
+            [Rtag (Location.mknoloc arity_string, [], true, [])]
+            Closed None
+        in
+        Ast_helper0.Typ.constr ~loc
+          {txt = Lident "function$"; loc}
+          [typ0; arity_type])
     | Ptyp_tuple tyl -> tuple ~loc ~attrs (List.map (sub.typ sub) tyl)
-    | Ptyp_constr
-        ( ({txt = Lident "function$"} as lid),
-          [({ptyp_desc = Ptyp_arrow (_, _, _, Some arity)} as t_arg)] ) ->
-      let encode_arity_string arity = "Has_arity" ^ string_of_int arity in
-      let arity_type ~loc arity =
-        Ast_helper0.Typ.variant ~loc
-          [Rtag ({txt = encode_arity_string arity; loc}, [], true, [])]
-          Closed None
-      in
-      constr ~loc ~attrs (map_loc sub lid)
-        [sub.typ sub t_arg; arity_type ~loc:Location.none arity]
     | Ptyp_constr (lid, tl) ->
       constr ~loc ~attrs (map_loc sub lid) (List.map (sub.typ sub) tl)
     | Ptyp_object (l, o) ->