Add support for |> in uncurried mode by desugaring it

Desugar the semantics of `|>` in uncurried mode so existing curried code still compiles. But the code will stop using `|>` after formatting.

For example: `3 |> add3(1,2)` would not compile when `add3` has 3 arguments. But after desugaring, the third argument is added.

Author: cristianoc

CHANGELOG.md

@@ -72,6 +72,7 @@ These are only breaking changes for unformatted code.
 - Treat uncurried application of primitives like curried application, which produces better output https://github.com/rescript-lang/rescript-compiler/pull/5851
 - New internal representation for uncurried functions using built-in type `function$<fun_type, arity>` this avoids having to declare all the possible arities ahead of time https://github.com/rescript-lang/rescript-compiler/pull/5870
 - PPX V3: allow uncurried `make` function and treat it like a curried one https://github.com/rescript-lang/rescript-compiler/pull/6081
+- Add support for `|>` in uncurried mode by desugaring it https://github.com/rescript-lang/rescript-compiler/pull/6083
 
 # 10.1.4
 

res_syntax/src/res_core.ml

@@ -2204,9 +2204,16 @@ and parseBinaryExpr ?(context = OrdinaryExpr) ?a p prec =
       let b = parseBinaryExpr ~context p tokenPrec in
       let loc = mkLoc a.Parsetree.pexp_loc.loc_start b.pexp_loc.loc_end in
       let expr =
-        Ast_helper.Exp.apply ~loc
-          (makeInfixOperator p token startPos endPos)
-          [(Nolabel, a); (Nolabel, b)]
+        match (token, b.pexp_desc) with
+        | BarGreater, Pexp_apply (funExpr, args)
+          when p.uncurried_config = Uncurried ->
+          {b with pexp_desc = Pexp_apply (funExpr, args @ [(Nolabel, a)])}
+        | BarGreater, _ when p.uncurried_config = Uncurried ->
+          Ast_helper.Exp.apply ~loc b [(Nolabel, a)]
+        | _ ->
+          Ast_helper.Exp.apply ~loc
+            (makeInfixOperator p token startPos endPos)
+            [(Nolabel, a); (Nolabel, b)]
       in
       Parser.eatBreadcrumb p;
       loop expr)

res_syntax/tests/printer/expr/Uncurried.res

@@ -0,0 +1,7 @@
+@@uncurried
+
+let add3 = (x,y,z) => x+y+z
+
+let triangle = 3 |> add3(1,2) |> add3(4,5)
+
+let () = 3 |> ignore

res_syntax/tests/printer/expr/expected/Uncurried.res.txt

@@ -0,0 +1,7 @@
+@@uncurried
+
+let add3 = (x, y, z) => x + y + z
+
+let triangle = add3(4, 5, add3(1, 2, 3))
+
+let () = ignore(3)