From bca424832dea17759a63c977d41da2de450617a3 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sat, 9 Nov 2024 09:17:05 +0900
Subject: [PATCH 1/9] Upgrade exponentiation to unified operator

Also make its output to use ES7 exponentiation (`**`) operator.

`**` is more concise, faster than `Math.pow()`,
works well with all numeric types include bigint.

We were already using it for bigint, now for int and float too.
---
 compiler/core/js_exp_make.ml                       |  7 +++++++
 compiler/core/js_exp_make.mli                      |  4 ++++
 compiler/core/js_op.ml                             |  3 ++-
 compiler/core/js_op_util.ml                        |  5 ++++-
 compiler/core/lam_analysis.ml                      |  9 +++++----
 compiler/core/lam_compile_primitive.ml             |  8 ++++++++
 compiler/core/lam_convert.ml                       |  2 ++
 compiler/core/lam_primitive.ml                     | 10 ++++++----
 compiler/core/lam_primitive.mli                    |  2 ++
 compiler/core/lam_print.ml                         |  2 ++
 compiler/ext/ext_int.ml                            |  8 ++++++++
 compiler/ext/ext_int.mli                           |  2 ++
 compiler/ml/lambda.ml                              |  2 ++
 compiler/ml/lambda.mli                             |  2 ++
 compiler/ml/printlambda.ml                         |  2 ++
 compiler/ml/unified_ops.ml                         | 13 +++++++++++++
 compiler/syntax/src/res_parens.ml                  | 12 +++++++-----
 compiler/syntax/src/res_parsetree_viewer.mli       |  1 +
 runtime/Pervasives.res                             |  4 +---
 runtime/Pervasives_mini.res                        |  1 +
 tests/tests/src/b.mjs                              |  2 +-
 tests/tests/src/exponentiation_precedence_test.mjs | 10 +++++-----
 tests/tests/src/test_pervasive.mjs                 |  2 +-
 tests/tests/src/unified_ops_test.mjs               |  9 +++++++++
 tests/tests/src/unified_ops_test.res               |  4 ++++
 tests/tests/src/variantsMatching.mjs               |  4 ++--
 26 files changed, 103 insertions(+), 27 deletions(-)

diff --git a/compiler/core/js_exp_make.ml b/compiler/core/js_exp_make.ml
index cc8d357043..c9238007c0 100644
--- a/compiler/core/js_exp_make.ml
+++ b/compiler/core/js_exp_make.ml
@@ -1533,6 +1533,7 @@ let unchecked_int32_minus ?comment e1 e2 : J.expression =
   float_minus ?comment e1 e2
 
 let float_div ?comment e1 e2 = bin ?comment Div e1 e2
+let float_pow ?comment e1 e2 = bin ?comment Pow e1 e2
 let float_notequal ?comment e1 e2 = bin ?comment NotEqEq e1 e2
 
 let int32_asr ?comment e1 e2 : J.expression =
@@ -1604,6 +1605,12 @@ let int32_mul ?comment (e1 : J.expression) (e2 : J.expression) : J.expression =
 let unchecked_int32_mul ?comment e1 e2 : J.expression =
   {comment; expression_desc = Bin (Mul, e1, e2)}
 
+let int32_pow ?comment (e1 : t) (e2 : t) : J.expression =
+  match (e1.expression_desc, e2.expression_desc) with
+  | Number (Int {i = i1}), Number (Int {i = i2}) ->
+    int ?comment (Ext_int.int32_pow i1 i2)
+  | _ -> {comment; expression_desc = Bin (Pow, e1, e2)}
+
 let rec int32_bxor ?comment (e1 : t) (e2 : t) : J.expression =
   match (e1.expression_desc, e2.expression_desc) with
   | Number (Int {i = i1}), Number (Int {i = i2}) ->
diff --git a/compiler/core/js_exp_make.mli b/compiler/core/js_exp_make.mli
index e890e4c6aa..e1fe0a5d3a 100644
--- a/compiler/core/js_exp_make.mli
+++ b/compiler/core/js_exp_make.mli
@@ -251,6 +251,8 @@ val int32_div : checked:bool -> ?comment:string -> t -> t -> t
 
 val int32_mod : checked:bool -> ?comment:string -> t -> t -> t
 
+val int32_pow : ?comment:string -> t -> t -> t
+
 val int32_lsl : ?comment:string -> t -> t -> t
 
 val int32_lsr : ?comment:string -> t -> t -> t
@@ -275,6 +277,8 @@ val float_notequal : ?comment:string -> t -> t -> t
 
 val float_mod : ?comment:string -> t -> t -> t
 
+val float_pow : ?comment:string -> t -> t -> t
+
 val int_comp : Lam_compat.comparison -> ?comment:string -> t -> t -> t
 
 val bool_comp : Lam_compat.comparison -> ?comment:string -> t -> t -> t
diff --git a/compiler/core/js_op.ml b/compiler/core/js_op.ml
index 15f9944b27..0d7558e7ad 100644
--- a/compiler/core/js_op.ml
+++ b/compiler/core/js_op.ml
@@ -105,7 +105,8 @@ type int_op =
   | Div
   (* x / y | 0 *)
   | Mod
-(* x  % y *)
+  (* x  % y *)
+  | Pow
 
 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Bitwise_operators
    {[
diff --git a/compiler/core/js_op_util.ml b/compiler/core/js_op_util.ml
index af6f3c5dcb..439c4463cf 100644
--- a/compiler/core/js_op_util.ml
+++ b/compiler/core/js_op_util.ml
@@ -40,7 +40,8 @@ let op_prec (op : Js_op.binop) =
   | Band -> (7, 7, 7)
   | Lsl | Lsr | Asr -> (10, 10, 11)
   | Plus | Minus -> (11, 11, 12)
-  | Mul | Div | Mod | Pow -> (12, 12, 13)
+  | Mul | Div | Mod -> (12, 12, 13)
+  | Pow -> (12, 14, 12)
 
 let op_int_prec (op : Js_op.int_op) =
   match op with
@@ -50,6 +51,7 @@ let op_int_prec (op : Js_op.int_op) =
   | Lsl | Lsr | Asr -> (10, 10, 11)
   | Plus | Minus -> (11, 11, 12)
   | Mul | Div | Mod -> (12, 12, 13)
+  | Pow -> (12, 14, 12)
 
 let op_str (op : Js_op.binop) =
   match op with
@@ -89,6 +91,7 @@ let op_int_str (op : Js_op.int_op) =
   | Mul -> "*"
   | Div -> "/"
   | Mod -> "%"
+  | Pow -> "**"
 
 let str_of_used_stats x =
   match (x : Js_op.used_stats) with
diff --git a/compiler/core/lam_analysis.ml b/compiler/core/lam_analysis.ml
index a95b382ca2..d99c83afe5 100644
--- a/compiler/core/lam_analysis.ml
+++ b/compiler/core/lam_analysis.ml
@@ -59,12 +59,13 @@ let rec no_side_effects (lam : Lam.t) : bool =
     (* bool primitives *)
     | Psequand | Psequor | Pnot | Pboolcomp _ | Pboolorder | Pboolmin | Pboolmax
     (* int primitives *)
-    | Pnegint | Paddint | Psubint | Pmulint | Pandint | Porint | Pxorint
-    | Plslint | Plsrint | Pasrint | Pintcomp _ | Pintorder | Pintmin | Pintmax
+    | Pnegint | Paddint | Psubint | Pmulint | Ppowint | Pandint | Porint
+    | Pxorint | Plslint | Plsrint | Pasrint | Pintcomp _ | Pintorder | Pintmin
+    | Pintmax
     (* float primitives *)
     | Pintoffloat | Pfloatofint | Pnegfloat | Paddfloat | Psubfloat | Pmulfloat
-    | Pdivfloat | Pmodfloat | Pfloatcomp _ | Pjscomp _ | Pfloatorder | Pfloatmin
-    | Pfloatmax
+    | Ppowfloat | Pdivfloat | Pmodfloat | Pfloatcomp _ | Pjscomp _ | Pfloatorder
+    | Pfloatmin | Pfloatmax
     (* bigint primitives *)
     | Pnegbigint | Paddbigint | Psubbigint | Pmulbigint | Ppowbigint
     | Pandbigint | Porbigint | Pxorbigint | Plslbigint | Pasrbigint
diff --git a/compiler/core/lam_compile_primitive.ml b/compiler/core/lam_compile_primitive.ml
index efea6c977b..58d488bb3b 100644
--- a/compiler/core/lam_compile_primitive.ml
+++ b/compiler/core/lam_compile_primitive.ml
@@ -250,6 +250,14 @@ let translate output_prefix loc (cxt : Lam_compile_context.t)
     match args with
     | [e1; e2] -> E.bigint_mod ~checked:!Js_config.check_div_by_zero e1 e2
     | _ -> assert false)
+  | Ppowint -> (
+    match args with
+    | [e1; e2] -> E.int32_pow e1 e2
+    | _ -> assert false)
+  | Ppowfloat -> (
+    match args with
+    | [e1; e2] -> E.float_pow e1 e2
+    | _ -> assert false)
   | Ppowbigint -> (
     match args with
     | [e1; e2] -> E.bigint_op Pow e1 e2
diff --git a/compiler/core/lam_convert.ml b/compiler/core/lam_convert.ml
index 74131236ab..ad74ba176b 100644
--- a/compiler/core/lam_convert.ml
+++ b/compiler/core/lam_convert.ml
@@ -251,6 +251,7 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
   | Pmulint -> prim ~primitive:Pmulint ~args loc
   | Pdivint _is_safe (*FIXME*) -> prim ~primitive:Pdivint ~args loc
   | Pmodint _is_safe (*FIXME*) -> prim ~primitive:Pmodint ~args loc
+  | Ppowint -> prim ~primitive:Ppowint ~args loc
   | Pandint -> prim ~primitive:Pandint ~args loc
   | Porint -> prim ~primitive:Porint ~args loc
   | Pxorint -> prim ~primitive:Pxorint ~args loc
@@ -283,6 +284,7 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
   | Pmulfloat -> prim ~primitive:Pmulfloat ~args loc
   | Pdivfloat -> prim ~primitive:Pdivfloat ~args loc
   | Pmodfloat -> prim ~primitive:Pmodfloat ~args loc
+  | Ppowfloat -> prim ~primitive:Ppowfloat ~args loc
   | Pfloatorder -> prim ~primitive:Pfloatorder ~args loc
   | Pfloatmin -> prim ~primitive:Pfloatmin ~args loc
   | Pfloatmax -> prim ~primitive:Pfloatmax ~args loc
diff --git a/compiler/core/lam_primitive.ml b/compiler/core/lam_primitive.ml
index 21cedb23e5..51ba970839 100644
--- a/compiler/core/lam_primitive.ml
+++ b/compiler/core/lam_primitive.ml
@@ -75,6 +75,7 @@ type t =
   | Pmulint
   | Pdivint
   | Pmodint
+  | Ppowint
   | Pandint
   | Porint
   | Pxorint
@@ -96,6 +97,7 @@ type t =
   | Pmulfloat
   | Pdivfloat
   | Pmodfloat
+  | Ppowfloat
   | Pfloatcomp of Lam_compat.comparison
   | Pfloatorder
   | Pfloatmin
@@ -199,12 +201,12 @@ let eq_primitive_approx (lhs : t) (rhs : t) =
   (* bool primitives *)
   | Psequand | Psequor | Pnot | Pboolcomp _ | Pboolorder | Pboolmin | Pboolmax
   (* int primitives *)
-  | Pisint | Pnegint | Paddint | Psubint | Pmulint | Pdivint | Pmodint | Pandint
-  | Porint | Pxorint | Plslint | Plsrint | Pasrint | Pintorder | Pintmin
-  | Pintmax
+  | Pisint | Pnegint | Paddint | Psubint | Pmulint | Pdivint | Pmodint | Ppowint
+  | Pandint | Porint | Pxorint | Plslint | Plsrint | Pasrint | Pintorder
+  | Pintmin | Pintmax
   (* float primitives *)
   | Pintoffloat | Pfloatofint | Pnegfloat | Paddfloat | Psubfloat | Pmulfloat
-  | Pdivfloat | Pmodfloat | Pfloatorder | Pfloatmin | Pfloatmax
+  | Pdivfloat | Pmodfloat | Ppowfloat | Pfloatorder | Pfloatmin | Pfloatmax
   (* bigint primitives *)
   | Pnegbigint | Paddbigint | Psubbigint | Pmulbigint | Pdivbigint | Pmodbigint
   | Ppowbigint | Pandbigint | Porbigint | Pxorbigint | Plslbigint | Pasrbigint
diff --git a/compiler/core/lam_primitive.mli b/compiler/core/lam_primitive.mli
index 4f358b525a..c7283ca927 100644
--- a/compiler/core/lam_primitive.mli
+++ b/compiler/core/lam_primitive.mli
@@ -69,6 +69,7 @@ type t =
   | Pmulint
   | Pdivint
   | Pmodint
+  | Ppowint
   | Pandint
   | Porint
   | Pxorint
@@ -90,6 +91,7 @@ type t =
   | Pmulfloat
   | Pdivfloat
   | Pmodfloat
+  | Ppowfloat
   | Pfloatcomp of Lam_compat.comparison
   | Pfloatorder
   | Pfloatmin
diff --git a/compiler/core/lam_print.ml b/compiler/core/lam_print.ml
index 17c18d6108..8f3fdabd53 100644
--- a/compiler/core/lam_print.ml
+++ b/compiler/core/lam_print.ml
@@ -116,6 +116,7 @@ let primitive ppf (prim : Lam_primitive.t) =
   | Pmulint -> fprintf ppf "*"
   | Pdivint -> fprintf ppf "/"
   | Pmodint -> fprintf ppf "mod"
+  | Ppowint -> fprintf ppf "**"
   | Pandint -> fprintf ppf "and"
   | Porint -> fprintf ppf "or"
   | Pxorint -> fprintf ppf "xor"
@@ -141,6 +142,7 @@ let primitive ppf (prim : Lam_primitive.t) =
   | Pmulfloat -> fprintf ppf "*."
   | Pdivfloat -> fprintf ppf "/."
   | Pmodfloat -> fprintf ppf "mod"
+  | Ppowfloat -> fprintf ppf "**"
   | Pfloatcomp Ceq -> fprintf ppf "==."
   | Pfloatcomp Cneq -> fprintf ppf "!=."
   | Pfloatcomp Clt -> fprintf ppf "<."
diff --git a/compiler/ext/ext_int.ml b/compiler/ext/ext_int.ml
index f31d4251de..92d292508f 100644
--- a/compiler/ext/ext_int.ml
+++ b/compiler/ext/ext_int.ml
@@ -34,3 +34,11 @@ let move = 0x1_0000_0000
 let int32_unsigned_to_int (n : int32) : int =
   let i = Int32.to_int n in
   if i < 0 then i + move else i
+
+let rec int32_pow (a : int32) = function
+  | 0l -> 1l
+  | 1l -> a
+  | n ->
+    let b = int32_pow a (Int32.div n 2l) in
+    let b = Int32.mul b b in
+    Int32.mul b (if Int32.rem n 2l = 0l then 1l else a)
diff --git a/compiler/ext/ext_int.mli b/compiler/ext/ext_int.mli
index acfc7af2ed..0c61810009 100644
--- a/compiler/ext/ext_int.mli
+++ b/compiler/ext/ext_int.mli
@@ -33,3 +33,5 @@ val int32_unsigned_to_int : int32 -> int
    works on 64 bit platform only
    given input as an uint32 and convert it io int64
 *)
+
+val int32_pow : int32 -> int32 -> int32
diff --git a/compiler/ml/lambda.ml b/compiler/ml/lambda.ml
index fcd1dc86ca..db163360c2 100644
--- a/compiler/ml/lambda.ml
+++ b/compiler/ml/lambda.ml
@@ -220,6 +220,7 @@ type primitive =
   | Pmulint
   | Pdivint of is_safe
   | Pmodint of is_safe
+  | Ppowint
   | Pandint
   | Porint
   | Pxorint
@@ -242,6 +243,7 @@ type primitive =
   | Psubfloat
   | Pmulfloat
   | Pdivfloat
+  | Ppowfloat
   | Pfloatcomp of comparison
   | Pfloatorder
   | Pfloatmin
diff --git a/compiler/ml/lambda.mli b/compiler/ml/lambda.mli
index 7f506ac62d..cb929d864a 100644
--- a/compiler/ml/lambda.mli
+++ b/compiler/ml/lambda.mli
@@ -183,6 +183,7 @@ type primitive =
   | Pmulint
   | Pdivint of is_safe
   | Pmodint of is_safe
+  | Ppowint
   | Pandint
   | Porint
   | Pxorint
@@ -205,6 +206,7 @@ type primitive =
   | Psubfloat
   | Pmulfloat
   | Pdivfloat
+  | Ppowfloat
   | Pfloatcomp of comparison
   | Pfloatorder
   | Pfloatmin
diff --git a/compiler/ml/printlambda.ml b/compiler/ml/printlambda.ml
index 4512355c34..9018c0c889 100644
--- a/compiler/ml/printlambda.ml
+++ b/compiler/ml/printlambda.ml
@@ -156,6 +156,7 @@ let primitive ppf = function
   | Pdivint Unsafe -> fprintf ppf "/u"
   | Pmodint Safe -> fprintf ppf "mod"
   | Pmodint Unsafe -> fprintf ppf "mod_unsafe"
+  | Ppowint -> fprintf ppf "**"
   | Pandint -> fprintf ppf "and"
   | Porint -> fprintf ppf "or"
   | Pxorint -> fprintf ppf "xor"
@@ -182,6 +183,7 @@ let primitive ppf = function
   | Pmulfloat -> fprintf ppf "*."
   | Pdivfloat -> fprintf ppf "/."
   | Pmodfloat -> fprintf ppf "mod"
+  | Ppowfloat -> fprintf ppf "**"
   | Pfloatcomp Ceq -> fprintf ppf "==."
   | Pfloatcomp Cneq -> fprintf ppf "!=."
   | Pfloatcomp Clt -> fprintf ppf "<."
diff --git a/compiler/ml/unified_ops.ml b/compiler/ml/unified_ops.ml
index c57c14bce0..5b3fea3ca1 100644
--- a/compiler/ml/unified_ops.ml
+++ b/compiler/ml/unified_ops.ml
@@ -161,6 +161,19 @@ let entries =
           string = None;
         };
     };
+    {
+      path = builtin "**";
+      name = "%pow";
+      form = Binary;
+      specialization =
+        {
+          int = Ppowint;
+          bool = None;
+          float = Some Ppowfloat;
+          bigint = Some Ppowbigint;
+          string = None;
+        };
+    };
   |]
 
 let index_by_path =
diff --git a/compiler/syntax/src/res_parens.ml b/compiler/syntax/src/res_parens.ml
index 336af9f77f..c0878e78f2 100644
--- a/compiler/syntax/src/res_parens.ml
+++ b/compiler/syntax/src/res_parens.ml
@@ -148,12 +148,14 @@ let binary_expr_operand ~is_lhs expr =
       else Nothing)
 
 let sub_binary_expr_operand parent_operator child_operator =
-  let prec_parent = ParsetreeViewer.operator_precedence parent_operator in
-  let prec_child = ParsetreeViewer.operator_precedence child_operator in
+  let open ParsetreeViewer in
+  let prec_parent = operator_precedence parent_operator in
+  let prec_child = operator_precedence child_operator in
+  Printf.eprintf "parent %s, %d; child %s, %d" parent_operator prec_parent
+    child_operator prec_child;
   prec_parent > prec_child
-  || prec_parent == prec_child
-     && not
-          (ParsetreeViewer.flattenable_operators parent_operator child_operator)
+  || is_equality_operator parent_operator
+     && is_equality_operator child_operator
   || (* a && b || c, add parens to (a && b) for readability, who knows the difference by heart… *)
   (parent_operator = "||" && child_operator = "&&")
 
diff --git a/compiler/syntax/src/res_parsetree_viewer.mli b/compiler/syntax/src/res_parsetree_viewer.mli
index 56e68a307b..610c78bb46 100644
--- a/compiler/syntax/src/res_parsetree_viewer.mli
+++ b/compiler/syntax/src/res_parsetree_viewer.mli
@@ -81,6 +81,7 @@ val is_unary_expression : Parsetree.expression -> bool
 val is_binary_operator : string -> bool
 val is_binary_expression : Parsetree.expression -> bool
 val is_rhs_binary_operator : string -> bool
+val is_equality_operator : string -> bool
 
 val flattenable_operators : string -> string -> bool
 
diff --git a/runtime/Pervasives.res b/runtime/Pervasives.res
index a19348538d..168bde7ab2 100644
--- a/runtime/Pervasives.res
+++ b/runtime/Pervasives.res
@@ -51,6 +51,7 @@ external \"*": ('a, 'a) => 'a = "%mul"
 external \"/": ('a, 'a) => 'a = "%div"
 external \"%": ('a, 'a) => 'a = "%mod"
 external mod: ('a, 'a) => 'a = "%mod"
+external \"**": ('a, 'a) => 'a = "%pow"
 
 /* Comparisons */
 /* Note: Later comparisons will be converted to unified operations too */
@@ -114,9 +115,6 @@ external \"-.": (float, float) => float = "%subfloat"
 external \"*.": (float, float) => float = "%mulfloat"
 external \"/.": (float, float) => float = "%divfloat"
 
-@deprecated("Use Core instead. This will be removed in v13") @val @scope("Math")
-external \"**": (float, float) => float = "pow"
-
 @deprecated("Use Core instead. This will be removed in v13") @val @scope("Math")
 external exp: float => float = "exp"
 
diff --git a/runtime/Pervasives_mini.res b/runtime/Pervasives_mini.res
index 9cf3cd90e4..eedba6fe6e 100644
--- a/runtime/Pervasives_mini.res
+++ b/runtime/Pervasives_mini.res
@@ -30,6 +30,7 @@ external \"*": (int, int) => int = "%mulint"
 external \"/": (int, int) => int = "%divint"
 external \"%": (int, int) => int = "%modint"
 external mod: (int, int) => int = "%modint"
+external \"**": (int, int) => int = "%powint"
 
 /* Comparisons */
 /* Note: Later comparisons will be converted to unified operations too */
diff --git a/tests/tests/src/b.mjs b/tests/tests/src/b.mjs
index 1738e2ec25..2d888ec7ee 100644
--- a/tests/tests/src/b.mjs
+++ b/tests/tests/src/b.mjs
@@ -4,7 +4,7 @@
 function f(point) {
   let y = point.y;
   let x = point.x;
-  return Math.pow(x * x + y * y, 2);
+  return (x * x + y * y) ** 2;
 }
 
 export {
diff --git a/tests/tests/src/exponentiation_precedence_test.mjs b/tests/tests/src/exponentiation_precedence_test.mjs
index 1f84a4ec3c..4d88b12de0 100644
--- a/tests/tests/src/exponentiation_precedence_test.mjs
+++ b/tests/tests/src/exponentiation_precedence_test.mjs
@@ -1,13 +1,13 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
 
-let a = Math.pow(2, Math.pow(3, 2));
+let a = 2 ** 3 ** 2;
 
-let b = Math.pow(2, Math.pow(-3, 2));
+let b = 2 ** (-3) ** 2;
 
-let c = Math.pow(Math.pow(2, 3), 2);
+let c = (2 ** 3) ** 2;
 
-let d = Math.pow(-2, 2);
+let d = (-2) ** 2;
 
 export {
   a,
@@ -15,4 +15,4 @@ export {
   c,
   d,
 }
-/* a Not a pure module */
+/* No side effect */
diff --git a/tests/tests/src/test_pervasive.mjs b/tests/tests/src/test_pervasive.mjs
index 0653322903..df9af152dc 100644
--- a/tests/tests/src/test_pervasive.mjs
+++ b/tests/tests/src/test_pervasive.mjs
@@ -187,7 +187,7 @@ function a17(prim) {
 }
 
 function a18(prim0, prim1) {
-  return Math.pow(prim0, prim1);
+  return prim0 ** prim1;
 }
 
 let f = Pervasives.$at;
diff --git a/tests/tests/src/unified_ops_test.mjs b/tests/tests/src/unified_ops_test.mjs
index c9635201cc..bb6cdd7683 100644
--- a/tests/tests/src/unified_ops_test.mjs
+++ b/tests/tests/src/unified_ops_test.mjs
@@ -59,6 +59,12 @@ function odd(n) {
   return n % 2 === 1;
 }
 
+let pow1 = 4;
+
+let pow2 = 2 ** 2;
+
+let pow3 = 2n ** 2n;
+
 let int = 3;
 
 export {
@@ -79,5 +85,8 @@ export {
   case2,
   even,
   odd,
+  pow1,
+  pow2,
+  pow3,
 }
 /* No side effect */
diff --git a/tests/tests/src/unified_ops_test.res b/tests/tests/src/unified_ops_test.res
index c35588167f..434f8e0651 100644
--- a/tests/tests/src/unified_ops_test.res
+++ b/tests/tests/src/unified_ops_test.res
@@ -20,3 +20,7 @@ let case2 = (a, b) => a + "test" + b
 
 let even = n => n % 2 == 0
 let odd = n => n % 2 == 1
+
+let pow1 = 2 ** 2
+let pow2 = 2. ** 2.
+let pow3 = 2n ** 2n
diff --git a/tests/tests/src/variantsMatching.mjs b/tests/tests/src/variantsMatching.mjs
index e4b281726f..dbf14100ae 100644
--- a/tests/tests/src/variantsMatching.mjs
+++ b/tests/tests/src/variantsMatching.mjs
@@ -333,9 +333,9 @@ let MyNullableExtended = {
 function area(shape) {
   switch (shape.kind) {
     case 1 :
-      return Math.PI * Math.pow(shape.radius, 2);
+      return Math.PI * (shape.radius ** 2);
     case "square" :
-      return Math.pow(shape.sideLength, 2);
+      return shape.sideLength ** 2;
     case "rectangle" :
       return shape.width * shape.height;
   }

From 79a85270248cbc0387b1c3182a5dbb2b2a1781b5 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sat, 9 Nov 2024 09:37:52 +0900
Subject: [PATCH 2/9] remove debug log

---
 compiler/syntax/src/res_parens.ml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/compiler/syntax/src/res_parens.ml b/compiler/syntax/src/res_parens.ml
index c0878e78f2..e42a6a6c9f 100644
--- a/compiler/syntax/src/res_parens.ml
+++ b/compiler/syntax/src/res_parens.ml
@@ -151,8 +151,6 @@ let sub_binary_expr_operand parent_operator child_operator =
   let open ParsetreeViewer in
   let prec_parent = operator_precedence parent_operator in
   let prec_child = operator_precedence child_operator in
-  Printf.eprintf "parent %s, %d; child %s, %d" parent_operator prec_parent
-    child_operator prec_child;
   prec_parent > prec_child
   || is_equality_operator parent_operator
      && is_equality_operator child_operator

From 54c750bbf25c0bb9b20166ef8c74fad080e8837f Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sat, 9 Nov 2024 09:48:15 +0900
Subject: [PATCH 3/9] adjust parens

---
 compiler/core/js_op_util.ml          | 4 ++--
 tests/tests/src/variantsMatching.mjs | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/compiler/core/js_op_util.ml b/compiler/core/js_op_util.ml
index 439c4463cf..373657adfb 100644
--- a/compiler/core/js_op_util.ml
+++ b/compiler/core/js_op_util.ml
@@ -41,7 +41,7 @@ let op_prec (op : Js_op.binop) =
   | Lsl | Lsr | Asr -> (10, 10, 11)
   | Plus | Minus -> (11, 11, 12)
   | Mul | Div | Mod -> (12, 12, 13)
-  | Pow -> (12, 14, 12)
+  | Pow -> (13, 14, 12)
 
 let op_int_prec (op : Js_op.int_op) =
   match op with
@@ -51,7 +51,7 @@ let op_int_prec (op : Js_op.int_op) =
   | Lsl | Lsr | Asr -> (10, 10, 11)
   | Plus | Minus -> (11, 11, 12)
   | Mul | Div | Mod -> (12, 12, 13)
-  | Pow -> (12, 14, 12)
+  | Pow -> (13, 14, 12)
 
 let op_str (op : Js_op.binop) =
   match op with
diff --git a/tests/tests/src/variantsMatching.mjs b/tests/tests/src/variantsMatching.mjs
index dbf14100ae..0485b35dc4 100644
--- a/tests/tests/src/variantsMatching.mjs
+++ b/tests/tests/src/variantsMatching.mjs
@@ -333,7 +333,7 @@ let MyNullableExtended = {
 function area(shape) {
   switch (shape.kind) {
     case 1 :
-      return Math.PI * (shape.radius ** 2);
+      return Math.PI * shape.radius ** 2;
     case "square" :
       return shape.sideLength ** 2;
     case "rectangle" :

From a64a2c0a195187b68efc7df8f1123b2ca5433428 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 03:43:47 +0900
Subject: [PATCH 4/9] result into int32

---
 compiler/core/js_exp_make.ml | 2 +-
 compiler/core/js_op.ml       | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/core/js_exp_make.ml b/compiler/core/js_exp_make.ml
index c9238007c0..0849460290 100644
--- a/compiler/core/js_exp_make.ml
+++ b/compiler/core/js_exp_make.ml
@@ -1608,7 +1608,7 @@ let unchecked_int32_mul ?comment e1 e2 : J.expression =
 let int32_pow ?comment (e1 : t) (e2 : t) : J.expression =
   match (e1.expression_desc, e2.expression_desc) with
   | Number (Int {i = i1}), Number (Int {i = i2}) ->
-    int ?comment (Ext_int.int32_pow i1 i2)
+    to_int32 (int ?comment (Ext_int.int32_pow i1 i2))
   | _ -> {comment; expression_desc = Bin (Pow, e1, e2)}
 
 let rec int32_bxor ?comment (e1 : t) (e2 : t) : J.expression =
diff --git a/compiler/core/js_op.ml b/compiler/core/js_op.ml
index 0d7558e7ad..9bbe3b50a2 100644
--- a/compiler/core/js_op.ml
+++ b/compiler/core/js_op.ml
@@ -106,7 +106,7 @@ type int_op =
   (* x / y | 0 *)
   | Mod
   (* x  % y *)
-  | Pow
+  | Pow (* x ** y | 0 *)
 
 (* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Bitwise_operators
    {[

From 9b90cc15dcf0ffe2b705ed2b9af852ad01bcb010 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 03:45:03 +0900
Subject: [PATCH 5/9] more exponentiation tests

---
 .../src/exponentiation_precedence_test.mjs    | 18 --------
 .../src/exponentiation_precedence_test.res    |  4 --
 tests/tests/src/exponentiation_test.mjs       | 45 +++++++++++++++++++
 tests/tests/src/exponentiation_test.res       | 22 +++++++++
 4 files changed, 67 insertions(+), 22 deletions(-)
 delete mode 100644 tests/tests/src/exponentiation_precedence_test.mjs
 delete mode 100644 tests/tests/src/exponentiation_precedence_test.res
 create mode 100644 tests/tests/src/exponentiation_test.mjs
 create mode 100644 tests/tests/src/exponentiation_test.res

diff --git a/tests/tests/src/exponentiation_precedence_test.mjs b/tests/tests/src/exponentiation_precedence_test.mjs
deleted file mode 100644
index 4d88b12de0..0000000000
--- a/tests/tests/src/exponentiation_precedence_test.mjs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Generated by ReScript, PLEASE EDIT WITH CARE
-
-
-let a = 2 ** 3 ** 2;
-
-let b = 2 ** (-3) ** 2;
-
-let c = (2 ** 3) ** 2;
-
-let d = (-2) ** 2;
-
-export {
-  a,
-  b,
-  c,
-  d,
-}
-/* No side effect */
diff --git a/tests/tests/src/exponentiation_precedence_test.res b/tests/tests/src/exponentiation_precedence_test.res
deleted file mode 100644
index 97c300005a..0000000000
--- a/tests/tests/src/exponentiation_precedence_test.res
+++ /dev/null
@@ -1,4 +0,0 @@
-let a = 2. ** 3. ** 2.
-let b = 2. ** -3. ** 2.
-let c = (2. ** 3.) ** 2.
-let d = -2. ** 2.
diff --git a/tests/tests/src/exponentiation_test.mjs b/tests/tests/src/exponentiation_test.mjs
new file mode 100644
index 0000000000..a3c9bb71de
--- /dev/null
+++ b/tests/tests/src/exponentiation_test.mjs
@@ -0,0 +1,45 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Mt from "./mt.mjs";
+
+let suites = {
+  contents: /* [] */0
+};
+
+let test_id = {
+  contents: 0
+};
+
+function eq(loc, x, y) {
+  Mt.eq_suites(test_id, suites, loc, x, y);
+}
+
+let intPow = ((a, b) => Math.pow(a, b) | 0);
+
+eq("File \"exponentiation_test.res\", line 10, characters 5-12", 2 ** 3 ** 2, Math.pow(2, Math.pow(3, 2)));
+
+eq("File \"exponentiation_test.res\", line 11, characters 5-12", 2 ** (-3) ** 2, Math.pow(2, Math.pow(-3, 2)));
+
+eq("File \"exponentiation_test.res\", line 12, characters 5-12", (2 ** 3) ** 2, Math.pow(Math.pow(2, 3), 2));
+
+eq("File \"exponentiation_test.res\", line 13, characters 5-12", (-2) ** 2, Math.pow(-2, 2));
+
+eq("File \"exponentiation_test.res\", line 15, characters 5-12", 512, intPow(2, intPow(3, 2)));
+
+eq("File \"exponentiation_test.res\", line 16, characters 5-12", 512, intPow(2, intPow(-3, 2)));
+
+eq("File \"exponentiation_test.res\", line 17, characters 5-12", 64, intPow(intPow(2, 3), 2));
+
+eq("File \"exponentiation_test.res\", line 18, characters 5-12", -2147483648, intPow(-2, 31));
+
+eq("File \"exponentiation_test.res\", line 19, characters 5-12", 0, intPow(2, 32));
+
+Mt.from_pair_suites("Exponentiation_test", suites.contents);
+
+export {
+  suites,
+  test_id,
+  eq,
+  intPow,
+}
+/*  Not a pure module */
diff --git a/tests/tests/src/exponentiation_test.res b/tests/tests/src/exponentiation_test.res
new file mode 100644
index 0000000000..cb4a54aef2
--- /dev/null
+++ b/tests/tests/src/exponentiation_test.res
@@ -0,0 +1,22 @@
+let suites: ref<Mt.pair_suites> = ref(list{})
+let test_id = ref(0)
+let eq = (loc, x, y) => Mt.eq_suites(~test_id, ~suites, loc, x, y)
+
+external jsPow: (float, float) => float = "Math.pow"
+
+let intPow: (int, int) => int = %raw(`(a, b) => Math.pow(a, b) | 0`)
+
+let () = {
+  eq(__LOC__, 2. ** 3. ** 2., jsPow(2., jsPow(3., 2.)))
+  eq(__LOC__, 2. ** -3. ** 2., jsPow(2., jsPow(-3., 2.)))
+  eq(__LOC__, (2. ** 3.) ** 2., jsPow(jsPow(2., 3.), 2.))
+  eq(__LOC__, -2. ** 2., jsPow(-2., 2.))
+
+  eq(__LOC__, 2 ** 3 ** 2, intPow(2, intPow(3, 2)))
+  eq(__LOC__, 2 ** -3 ** 2, intPow(2, intPow(-3, 2)))
+  eq(__LOC__, (2 ** 3) ** 2, intPow(intPow(2, 3), 2))
+  eq(__LOC__, -2 ** 31, intPow(-2, 31))
+  eq(__LOC__, 2 ** 32, intPow(2, 32))
+}
+
+let () = Mt.from_pair_suites(__MODULE__, suites.contents)

From 0add4e356e6c9d45d37cf0ce5e68a00cc196431b Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 04:03:33 +0900
Subject: [PATCH 6/9] make sure it is int32

---
 compiler/core/js_exp_make.ml       | 2 +-
 tests/tests/src/test_pervasive.mjs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/core/js_exp_make.ml b/compiler/core/js_exp_make.ml
index 0849460290..c43bd4d244 100644
--- a/compiler/core/js_exp_make.ml
+++ b/compiler/core/js_exp_make.ml
@@ -1609,7 +1609,7 @@ let int32_pow ?comment (e1 : t) (e2 : t) : J.expression =
   match (e1.expression_desc, e2.expression_desc) with
   | Number (Int {i = i1}), Number (Int {i = i2}) ->
     to_int32 (int ?comment (Ext_int.int32_pow i1 i2))
-  | _ -> {comment; expression_desc = Bin (Pow, e1, e2)}
+  | _ -> to_int32 (float_pow ?comment e1 e2)
 
 let rec int32_bxor ?comment (e1 : t) (e2 : t) : J.expression =
   match (e1.expression_desc, e2.expression_desc) with
diff --git a/tests/tests/src/test_pervasive.mjs b/tests/tests/src/test_pervasive.mjs
index df9af152dc..0771c48e88 100644
--- a/tests/tests/src/test_pervasive.mjs
+++ b/tests/tests/src/test_pervasive.mjs
@@ -187,7 +187,7 @@ function a17(prim) {
 }
 
 function a18(prim0, prim1) {
-  return prim0 ** prim1;
+  return prim0 ** prim1 | 0;
 }
 
 let f = Pervasives.$at;

From c3dc1a068445b368552dc5fc300e2b5908051600 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 04:05:33 +0900
Subject: [PATCH 7/9] remove unnecessary guard for constants

---
 compiler/core/js_exp_make.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/core/js_exp_make.ml b/compiler/core/js_exp_make.ml
index c43bd4d244..c0ec1eecb1 100644
--- a/compiler/core/js_exp_make.ml
+++ b/compiler/core/js_exp_make.ml
@@ -1608,7 +1608,7 @@ let unchecked_int32_mul ?comment e1 e2 : J.expression =
 let int32_pow ?comment (e1 : t) (e2 : t) : J.expression =
   match (e1.expression_desc, e2.expression_desc) with
   | Number (Int {i = i1}), Number (Int {i = i2}) ->
-    to_int32 (int ?comment (Ext_int.int32_pow i1 i2))
+    int ?comment (Ext_int.int32_pow i1 i2)
   | _ -> to_int32 (float_pow ?comment e1 e2)
 
 let rec int32_bxor ?comment (e1 : t) (e2 : t) : J.expression =

From 73dedfb14093097ab1916f462be9e1e2686dff0f Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 09:53:15 +0900
Subject: [PATCH 8/9] add changelog

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dde3c2e946..4ae435e261 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@
 
 - Introduce "Unified operators" for arithmetic operators (`+`, `-`, `*`, `/`, `mod`). https://github.com/rescript-lang/rescript-compiler/pull/7057
 - Add remainder (`%`, aka modulus) operator. https://github.com/rescript-lang/rescript-compiler/pull/7152
+- Allow exponentiation (`**`) operator for `int` and `float`, using ES7 `**`. https://github.com/rescript-lang/rescript-compiler/pull/7153
 
 # 12.0.0-alpha.4
 

From 6a077e283599b6fff187c768aa697c8aa125e8c5 Mon Sep 17 00:00:00 2001
From: Hyeseong Kim <hey@hyeseong.kim>
Date: Sun, 10 Nov 2024 09:58:42 +0900
Subject: [PATCH 9/9] add a test

---
 tests/tests/src/exponentiation_test.mjs | 23 ++++++++++++++---------
 tests/tests/src/exponentiation_test.res |  3 +++
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/tests/tests/src/exponentiation_test.mjs b/tests/tests/src/exponentiation_test.mjs
index a3c9bb71de..cd1b851151 100644
--- a/tests/tests/src/exponentiation_test.mjs
+++ b/tests/tests/src/exponentiation_test.mjs
@@ -16,23 +16,27 @@ function eq(loc, x, y) {
 
 let intPow = ((a, b) => Math.pow(a, b) | 0);
 
-eq("File \"exponentiation_test.res\", line 10, characters 5-12", 2 ** 3 ** 2, Math.pow(2, Math.pow(3, 2)));
+let four = 4;
 
-eq("File \"exponentiation_test.res\", line 11, characters 5-12", 2 ** (-3) ** 2, Math.pow(2, Math.pow(-3, 2)));
+eq("File \"exponentiation_test.res\", line 11, characters 5-12", 2 ** 3 ** 2, Math.pow(2, Math.pow(3, 2)));
 
-eq("File \"exponentiation_test.res\", line 12, characters 5-12", (2 ** 3) ** 2, Math.pow(Math.pow(2, 3), 2));
+eq("File \"exponentiation_test.res\", line 12, characters 5-12", 2 ** (-3) ** 2, Math.pow(2, Math.pow(-3, 2)));
 
-eq("File \"exponentiation_test.res\", line 13, characters 5-12", (-2) ** 2, Math.pow(-2, 2));
+eq("File \"exponentiation_test.res\", line 13, characters 5-12", (2 ** 3) ** 2, Math.pow(Math.pow(2, 3), 2));
 
-eq("File \"exponentiation_test.res\", line 15, characters 5-12", 512, intPow(2, intPow(3, 2)));
+eq("File \"exponentiation_test.res\", line 14, characters 5-12", (-2) ** 2, Math.pow(-2, 2));
 
-eq("File \"exponentiation_test.res\", line 16, characters 5-12", 512, intPow(2, intPow(-3, 2)));
+eq("File \"exponentiation_test.res\", line 16, characters 5-12", 512, intPow(2, intPow(3, 2)));
 
-eq("File \"exponentiation_test.res\", line 17, characters 5-12", 64, intPow(intPow(2, 3), 2));
+eq("File \"exponentiation_test.res\", line 17, characters 5-12", 512, intPow(2, intPow(-3, 2)));
 
-eq("File \"exponentiation_test.res\", line 18, characters 5-12", -2147483648, intPow(-2, 31));
+eq("File \"exponentiation_test.res\", line 18, characters 5-12", 64, intPow(intPow(2, 3), 2));
 
-eq("File \"exponentiation_test.res\", line 19, characters 5-12", 0, intPow(2, 32));
+eq("File \"exponentiation_test.res\", line 19, characters 5-12", -2147483648, intPow(-2, 31));
+
+eq("File \"exponentiation_test.res\", line 20, characters 5-12", 0, intPow(2, 32));
+
+eq("File \"exponentiation_test.res\", line 22, characters 5-12", 256, four ** four | 0);
 
 Mt.from_pair_suites("Exponentiation_test", suites.contents);
 
@@ -41,5 +45,6 @@ export {
   test_id,
   eq,
   intPow,
+  four,
 }
 /*  Not a pure module */
diff --git a/tests/tests/src/exponentiation_test.res b/tests/tests/src/exponentiation_test.res
index cb4a54aef2..0d0caa7b21 100644
--- a/tests/tests/src/exponentiation_test.res
+++ b/tests/tests/src/exponentiation_test.res
@@ -5,6 +5,7 @@ let eq = (loc, x, y) => Mt.eq_suites(~test_id, ~suites, loc, x, y)
 external jsPow: (float, float) => float = "Math.pow"
 
 let intPow: (int, int) => int = %raw(`(a, b) => Math.pow(a, b) | 0`)
+let four: int = %raw(`4`)
 
 let () = {
   eq(__LOC__, 2. ** 3. ** 2., jsPow(2., jsPow(3., 2.)))
@@ -17,6 +18,8 @@ let () = {
   eq(__LOC__, (2 ** 3) ** 2, intPow(intPow(2, 3), 2))
   eq(__LOC__, -2 ** 31, intPow(-2, 31))
   eq(__LOC__, 2 ** 32, intPow(2, 32))
+
+  eq(__LOC__, 4 ** 4, four ** four)
 }
 
 let () = Mt.from_pair_suites(__MODULE__, suites.contents)