Simplify ast async: add async flag directly where it's needed.

Author: cristianoc

CHANGELOG.md

@@ -24,11 +24,6 @@
 - AST: always put type parameters first in function definitions. https://github.com/rescript-lang/rescript/pull/7233
 - AST cleanup: Remove `@res.async` attribute from the internal representation, and add a flag to untyped and typed ASTs instead. https://github.com/rescript-lang/rescript/pull/7234
 
-#### :house: Internal
-
-- AST cleanup: Prepare for ast async cleanup: Refactor code for "@res.async" payload handling and clean up handling of type and term parameters, so that now each `=>` in a function definition corresponds to a function. https://github.com/rescript-lang/rescript/pull/7223
-
-
 # 12.0.0-alpha.7
 
 #### :bug: Bug fix

compiler/ml/ast_async.ml

@@ -4,18 +4,6 @@ let rec dig_async_payload_from_function (expr : Parsetree.expression) =
   | Pexp_newtype (_, body) -> dig_async_payload_from_function body
   | _ -> false
 
-let add_async_attribute ~async (body : Parsetree.expression) =
-  if async then
-    let rec add_to_fun (exp : Parsetree.expression) =
-      match exp.pexp_desc with
-      | Pexp_newtype (txt, e) ->
-        {exp with pexp_desc = Pexp_newtype (txt, add_to_fun e)}
-      | Pexp_fun f -> {exp with pexp_desc = Pexp_fun {f with async}}
-      | _ -> exp
-    in
-    add_to_fun body
-  else body
-
 let add_promise_type ?(loc = Location.none) ~async
     (result : Parsetree.expression) =
   if async then

compiler/ml/ast_uncurried.ml

@@ -6,11 +6,11 @@ let uncurried_type ~arity (t_arg : Parsetree.core_type) =
     {t_arg with ptyp_desc = Ptyp_arrow (l, t1, t2, Some arity)}
   | _ -> assert false
 
-let uncurried_fun ~arity fun_expr =
+let uncurried_fun ?(async = false) ~arity fun_expr =
   let fun_expr =
     match fun_expr.Parsetree.pexp_desc with
     | Pexp_fun f ->
-      {fun_expr with pexp_desc = Pexp_fun {f with arity = Some arity}}
+      {fun_expr with pexp_desc = Pexp_fun {f with arity = Some arity; async}}
     | _ -> assert false
   in
   fun_expr

compiler/ml/pprintast.ml

@@ -993,17 +993,19 @@ and binding ctxt f {pvb_pat = p; pvb_expr = x; _} =
     if x.pexp_attributes <> [] then pp f "=@;%a" (expression ctxt) x
     else
       match x.pexp_desc with
-      | Pexp_fun {arg_label = label; default = eo; lhs = p; rhs = e; arity} ->
+      | Pexp_fun
+          {arg_label = label; default = eo; lhs = p; rhs = e; arity; async} ->
         let arity_str =
           match arity with
           | None -> ""
           | Some arity -> "[arity:" ^ string_of_int arity ^ "]"
         in
+        let async_str = if async then "async " else "" in
         if label = Nolabel then
-          pp f "%s%a@ %a" arity_str (simple_pattern ctxt) p
+          pp f "%s%s%a@ %a" async_str arity_str (simple_pattern ctxt) p
             pp_print_pexp_function e
         else
-          pp f "%s%a@ %a" arity_str (label_exp ctxt) (label, eo, p)
+          pp f "%s%s%a@ %a" async_str arity_str (label_exp ctxt) (label, eo, p)
             pp_print_pexp_function e
       | Pexp_newtype (str, e) ->
         pp f "(type@ %s)@ %a" str.txt pp_print_pexp_function e

compiler/syntax/src/jsx_v4.ml

@@ -1125,7 +1125,7 @@ let map_binding ~config ~empty_loc ~pstr_loc ~file_name ~rec_flag binding =
       | _ -> Pat.record (List.rev patterns_with_label) Open
     in
     let expression =
-      Exp.fun_ ~arity:(Some 1) Nolabel None
+      Exp.fun_ ~arity:(Some 1) ~async:is_async Nolabel None
         (Pat.constraint_ record_pattern
            (Typ.constr ~loc:empty_loc
               {txt = Lident "props"; loc = empty_loc}
@@ -1140,7 +1140,6 @@ let map_binding ~config ~empty_loc ~pstr_loc ~file_name ~rec_flag binding =
                 | _ -> [Typ.any ()]))))
         expression
     in
-    let expression = Ast_async.add_async_attribute ~async:is_async expression in
     let expression =
       (* Add new tupes (type a,b,c) to make's definition *)
       newtypes

compiler/syntax/src/res_core.ml

@@ -1537,7 +1537,7 @@ and parse_ternary_expr left_operand p =
   | _ -> left_operand
 
 and parse_es6_arrow_expression ?(arrow_attrs = []) ?(arrow_start_pos = None)
-    ?context ?term_parameters p =
+    ?context ?term_parameters ~async p =
   let start_pos = p.Parser.start_pos in
   Parser.leave_breadcrumb p Grammar.Es6ArrowExpr;
   (* Parsing function parameters and attributes:
@@ -1609,7 +1609,9 @@ and parse_es6_arrow_expression ?(arrow_attrs = []) ?(arrow_start_pos = None)
       term_parameters body
   in
   let arrow_expr =
-    Ast_uncurried.uncurried_fun ~arity:(List.length term_parameters) arrow_expr
+    Ast_uncurried.uncurried_fun
+      ~arity:(List.length term_parameters)
+      ~async arrow_expr
   in
   let arrow_expr =
     match type_param_opt with
@@ -2159,7 +2161,7 @@ and parse_operand_expr ~context p =
       then
         let arrow_attrs = !attrs in
         let () = attrs := [] in
-        parse_es6_arrow_expression ~arrow_attrs ~context p
+        parse_es6_arrow_expression ~async:false ~arrow_attrs ~context p
       else parse_unary_expr p
   in
   (* let endPos = p.Parser.prevEndPos in *)
@@ -3000,7 +3002,7 @@ and parse_braced_or_record_expr p =
         let loc = mk_loc start_pos ident_end_pos in
         let ident = Location.mkloc (Longident.last path_ident.txt) loc in
         let a =
-          parse_es6_arrow_expression
+          parse_es6_arrow_expression ~async:false
             ~term_parameters:
               [
                 {
@@ -3303,8 +3305,8 @@ and parse_expr_block ?first p =
 and parse_async_arrow_expression ?(arrow_attrs = []) p =
   let start_pos = p.Parser.start_pos in
   Parser.expect (Lident "async") p;
-  Ast_async.add_async_attribute ~async:true
-    (parse_es6_arrow_expression ~arrow_attrs ~arrow_start_pos:(Some start_pos) p)
+  parse_es6_arrow_expression ~async:true ~arrow_attrs
+    ~arrow_start_pos:(Some start_pos) p
 
 and parse_await_expression p =
   let await_loc = mk_loc p.Parser.start_pos p.end_pos in

tests/syntax_tests/data/parsing/grammar/expressions/expected/async.res.txt

@@ -1,4 +1,4 @@
-let greetUser [arity:1]userId =
+let greetUser async [arity:1]userId =
   ((let name = ((getUserName userId)[@res.await ]) in
     ({js|Hello |js} ^ name) ^ {js|!|js})
   [@res.braces ])
@@ -22,7 +22,7 @@ let f =
     else (async fun [arity:2]c -> fun d -> (c - d : int)))
   [@res.ternary ])
 let foo = async ~a:((34)[@res.namedArgLoc ])
-let bar [arity:1]~a:((a)[@res.namedArgLoc ])  = a + 1
+let bar async [arity:1]~a:((a)[@res.namedArgLoc ])  = a + 1
 let ex1 = ((3)[@res.await ]) + ((4)[@res.await ])
 let ex2 = ((3)[@res.await ]) ** ((4)[@res.await ])
 let ex3 = ((foo |.u (bar ~arg:((arg)[@res.namedArgLoc ])))[@res.await ])