Parser/Printer: unify uncurried functions of arity 0, and of arity 1 taking unit. (#5825)

* Test: don't emit arity zero from the parser.

* Clean up: remove "(u)" encoding for uncurried unariy application.

* Update CHANGELOG.md

* Use `res.uapp` for uncurried app attribute coming from the parser.

* Clean up test.

* rename

* Update CHANGELOG.md

Author: cristianoc

CHANGELOG.md

@@ -20,6 +20,8 @@
 - Add support for partial application of uncurried functions: with uncurried application one can provide a
 subset of the arguments, and return a curried type with the remaining ones https://github.com/rescript-lang/rescript-compiler/pull/5805
 - Add support for uncurried externals https://github.com/rescript-lang/rescript-compiler/pull/5815 https://github.com/rescript-lang/rescript-compiler/pull/5819
+- Parser/Printer: unify uncurried functions of arity 0, and of arity 1 taking unit. There's now only arity 1 in the source language. https://github.com/rescript-lang/rescript-compiler/pull/5825
+
 
 #### :boom: Breaking Change
 
@@ -32,7 +34,6 @@ subset of the arguments, and return a curried type with the remaining ones https
 - Curried after uncurried is not fused anymore: `(. x) => y => 3` is not equivalent to `(. x, y) => 3` anymore. It's instead equivalent to `(. x) => { y => 3 }`.
 Also, `(. int) => string => bool` is not equivalen to `(. int, string) => bool` anymore.
 These are only breaking changes for unformatted code.
-- Distinguish between uncurried type `(. ()) => int`, whch takes 0 arguments, and `(. unit) => int` which takes 1 argument of type `unit` https://github.com/rescript-lang/rescript-compiler/pull/5821
 
 #### :bug: Bug Fix
 

jscomp/frontend/ast_attributes.ml

@@ -305,9 +305,12 @@ let iter_process_bs_string_or_int_as (attrs : Parsetree.attributes) =
                         _;
                       };
                     ]
-                  when Ast_utf8_string_interp.parse_processed_delim delim_ <> None -> (
+                  when Ast_utf8_string_interp.parse_processed_delim delim_
+                       <> None -> (
                     let delim =
-                      match Ast_utf8_string_interp.parse_processed_delim delim_ with
+                      match
+                        Ast_utf8_string_interp.parse_processed_delim delim_
+                      with
                       | None -> assert false
                       | Some delim -> delim
                     in
@@ -338,6 +341,9 @@ let locg = Location.none
 let is_bs (attr : attr) =
   match attr with { Location.txt = "bs"; _ }, _ -> true | _ -> false
 
+let is_res_uapp (attr : attr) =
+  match attr with { Location.txt = "res.uapp"; _ }, _ -> true | _ -> false
+
 let bs_get : attr = ({ txt = "bs.get"; loc = locg }, Ast_payload.empty)
 
 let bs_get_index : attr =

jscomp/frontend/ast_attributes.mli

@@ -72,6 +72,9 @@ val is_bs : attr -> bool
 (* val is_optional : attr -> bool
    val is_bs_as : attr -> bool *)
 
+(* Attribute for uncurried application coming from the ReScript parser *)
+val is_res_uapp : attr -> bool
+
 val bs_get : attr
 
 val bs_get_index : attr

jscomp/frontend/ast_exp_apply.ml

@@ -158,8 +158,9 @@ let app_exp_mapper (e : exp) (self : Bs_ast_mapper.mapper) (fn : exp)
                   })
           | _ -> (
               match
-                ( Ext_list.exclude_with_val f_.pexp_attributes
-                    Ast_attributes.is_bs,
+                ( Ext_list.exclude_with_val f_.pexp_attributes (fun a ->
+                      Ast_attributes.is_bs a
+                      || Ast_attributes.is_res_uapp a),
                   f_.pexp_desc )
               with
               | Some other_attributes, Pexp_apply (fn1, args) ->
@@ -173,8 +174,8 @@ let app_exp_mapper (e : exp) (self : Bs_ast_mapper.mapper) (fn : exp)
                     fn1.pexp_attributes;
                   {
                     pexp_desc =
-                      Ast_uncurry_apply.uncurry_fn_apply e.pexp_loc self fn1
-                        ((Nolabel, a) :: args);
+                      Ast_uncurry_apply.uncurry_fn_apply ~arity0:(op = "|.")
+                        e.pexp_loc self fn1 ((Nolabel, a) :: args);
                     pexp_loc = e.pexp_loc;
                     pexp_attributes = e.pexp_attributes @ other_attributes;
                   }
@@ -183,7 +184,8 @@ let app_exp_mapper (e : exp) (self : Bs_ast_mapper.mapper) (fn : exp)
                      Uncurried unary application *)
                   {
                     pexp_desc =
-                      Ast_uncurry_apply.uncurry_fn_apply e.pexp_loc self f
+                      Ast_uncurry_apply.uncurry_fn_apply ~arity0:false
+                        e.pexp_loc self f
                         [ (Nolabel, a) ];
                     pexp_loc = e.pexp_loc;
                     pexp_attributes = e.pexp_attributes;
@@ -283,11 +285,25 @@ let app_exp_mapper (e : exp) (self : Bs_ast_mapper.mapper) (fn : exp)
           match
             Ext_list.exclude_with_val e.pexp_attributes Ast_attributes.is_bs
           with
-          | None -> default_expr_mapper self e
           | Some pexp_attributes ->
               {
                 e with
                 pexp_desc =
-                  Ast_uncurry_apply.uncurry_fn_apply e.pexp_loc self fn args;
+                  Ast_uncurry_apply.uncurry_fn_apply ~arity0:true e.pexp_loc
+                    self fn args;
                 pexp_attributes;
-              }))
+              }
+          | None -> (
+              match
+                Ext_list.exclude_with_val e.pexp_attributes
+                  Ast_attributes.is_res_uapp
+              with
+              | Some pexp_attributes ->
+                  {
+                    e with
+                    pexp_desc =
+                      Ast_uncurry_apply.uncurry_fn_apply ~arity0:false
+                        e.pexp_loc self fn args;
+                    pexp_attributes;
+                  }
+              | None -> default_expr_mapper self e)))

jscomp/frontend/ast_uncurry_apply.ml

@@ -44,8 +44,9 @@ let opaque_full_apply ~loc (e : exp) : Parsetree.expression_desc =
         [ (Nolabel, e) ],
       Typ.any ~loc () )
 
-let generic_apply loc (self : Bs_ast_mapper.mapper) (obj : Parsetree.expression)
-    (args : Ast_compatible.args) (cb : loc -> exp -> exp) =
+let generic_apply ~arity0 loc (self : Bs_ast_mapper.mapper)
+    (obj : Parsetree.expression) (args : Ast_compatible.args)
+    (cb : loc -> exp -> exp) =
   let obj = self.expr self obj in
   let args =
     Ext_list.map args (fun (lbl, e) ->
@@ -57,7 +58,8 @@ let generic_apply loc (self : Bs_ast_mapper.mapper) (obj : Parsetree.expression)
     match args with
     | [
      (Nolabel, { pexp_desc = Pexp_construct ({ txt = Lident "()" }, None) });
-    ] ->
+    ]
+      when arity0 ->
         []
     | _ -> args
   in
@@ -128,9 +130,9 @@ let method_apply loc (self : Bs_ast_mapper.mapper) (obj : Parsetree.expression)
             ])
          args)
 
-let uncurry_fn_apply loc self fn args =
-  generic_apply loc self fn args (fun _ obj -> obj)
+let uncurry_fn_apply ~arity0 loc self fn args =
+  generic_apply ~arity0 loc self fn args (fun _ obj -> obj)
 
 let property_apply loc self obj name args =
-  generic_apply loc self obj args (fun loc obj ->
+  generic_apply ~arity0:true loc self obj args (fun loc obj ->
       Exp.send ~loc obj { txt = name; loc })

jscomp/frontend/ast_uncurry_apply.mli

@@ -25,6 +25,7 @@
 (* TODO: the interface is not reusable, it depends on too much context *)
 
 val uncurry_fn_apply :
+  arity0:bool ->
   Location.t ->
   Bs_ast_mapper.mapper ->
   Parsetree.expression ->

jscomp/test/UncurriedExternals.js

@@ -32,6 +32,8 @@ var te = (function (prim) {
       RE_EXN_ID: "Not_found"
     });
 
+var tcr = {};
+
 var StandardNotation = {
   dd: dd,
   h: h,
@@ -40,7 +42,8 @@ var StandardNotation = {
   mf: mf,
   tg: tg,
   tc: tc,
-  te: te
+  te: te,
+  tcr: tcr
 };
 
 function dd$1(param) {
@@ -74,6 +77,8 @@ var te$1 = (function (prim) {
       RE_EXN_ID: "Not_found"
     });
 
+var tcr$1 = {};
+
 exports.StandardNotation = StandardNotation;
 exports.dd = dd$1;
 exports.h = h$1;
@@ -83,4 +88,5 @@ exports.mf = mf$1;
 exports.tg = tg$1;
 exports.tc = tc$1;
 exports.te = te$1;
+exports.tcr = tcr$1;
 /* h Not a pure module */

jscomp/test/UncurriedExternals.res

@@ -23,6 +23,9 @@ module StandardNotation = {
 
   external toException: (. exn) => exn = "%identity"
   let te = toException(. Not_found)
+
+  @obj external ccreate : (. unit) => string = ""
+  let tcr = ccreate(.)
 }
 
 @@uncurried
@@ -51,3 +54,6 @@ let tc = copy("abc")
 
 external toException: exn => exn = "%identity"
 let te = toException(Not_found)
+
+@obj external ucreate : unit => string = ""
+let tcr = ucreate()

jscomp/test/reactTestUtils.js

@@ -7,14 +7,14 @@ var Caml_option = require("../../lib/js/caml_option.js");
 var TestUtils = require("react-dom/test-utils");
 
 function act(func) {
-  var reactFunc = function () {
+  var reactFunc = function (param) {
     Curry._1(func, undefined);
   };
   TestUtils.act(reactFunc);
 }
 
 function actAsync(func) {
-  return TestUtils.act(function () {
+  return TestUtils.act(function (param) {
               return Curry._1(func, undefined);
             });
 }

jscomp/test/uncurried_cast.js

@@ -76,7 +76,7 @@ var StandardNotation = {
   anInt: anInt
 };
 
-function testRaise$1() {
+function testRaise$1(param) {
   return raise({
               RE_EXN_ID: E
             });