[Belt] Save allocations by manually inlining

Author: chenglou

jscomp/others/belt_Id.ml

@@ -60,7 +60,9 @@ module MakeComparable (M : sig
 struct
   type identity
   type t = M.t
-  let cmp = (fun[@bs] a b -> M.cmp a b)
+  (* see https://github.com/BuckleScript/bucklescript/pull/2589/files/5ef875b7665ee08cfdc59af368fc52bac1fe9130#r173330825 *)
+  let cmp = 
+    let cmp = M.cmp in fun[@bs] a b -> cmp a b
 end
 
 let comparableU
@@ -73,8 +75,15 @@ let comparableU
     end) in 
   (module N : Comparable with type t = key)
 
-let comparable cmp =
-  comparableU (fun[@bs] a b -> cmp a b)
+let comparable
+  (type key) 
+  cmp   
+  =
+  let module N = MakeComparable(struct
+      type t = key
+      let cmp = cmp
+    end) in 
+  (module N : Comparable with type t = key)
 
 module type Hashable = sig 
   type identity 
@@ -105,8 +114,10 @@ module MakeHashable (M : sig
 struct
   type identity
   type t = M.t
-  let hash = (fun[@bs] a -> M.hash a)
-  let eq = (fun[@bs] a b -> M.eq a b)
+  let hash = 
+    let hash = M.hash in fun[@bs] a -> hash a
+  let eq = 
+    let eq = M.eq in fun[@bs] a b -> eq a b
 end
 
 let hashableU (type key) ~hash ~eq = 
@@ -117,7 +128,10 @@ let hashableU (type key) ~hash ~eq =
   end) in 
   (module N : Hashable with type t = key) 
 
-let hashable ~hash ~eq =
-  hashableU
-    ~hash:(fun [@bs] a -> hash a)
-    ~eq:(fun [@bs] a b -> eq a b)
+let hashable (type key) ~hash ~eq = 
+  let module N = MakeHashable(struct 
+    type t = key 
+    let hash = hash 
+    let eq = eq 
+  end) in 
+  (module N : Hashable with type t = key) 

lib/js/belt_Id.js

@@ -8,19 +8,17 @@ function MakeComparableU(M) {
 }
 
 function MakeComparable(M) {
-  var cmp = function (a, b) {
-    return Curry._2(M[/* cmp */0], a, b);
-  };
-  return /* module */[/* cmp */cmp];
+  var cmp = M[/* cmp */0];
+  var cmp$1 = Curry.__2(cmp);
+  return /* module */[/* cmp */cmp$1];
 }
 
 function comparableU(cmp) {
   return /* module */[/* cmp */cmp];
 }
 
 function comparable(cmp) {
-  var M = /* module */[/* cmp */Curry.__2(cmp)];
-  var cmp$1 = M[/* cmp */0];
+  var cmp$1 = Curry.__2(cmp);
   return /* module */[/* cmp */cmp$1];
 }
 
@@ -34,15 +32,13 @@ function MakeHashableU(M) {
 }
 
 function MakeHashable(M) {
-  var hash = function (a) {
-    return Curry._1(M[/* hash */0], a);
-  };
-  var eq = function (a, b) {
-    return Curry._2(M[/* eq */1], a, b);
-  };
+  var hash = M[/* hash */0];
+  var hash$1 = Curry.__1(hash);
+  var eq = M[/* eq */1];
+  var eq$1 = Curry.__2(eq);
   return /* module */[
-          /* hash */hash,
-          /* eq */eq
+          /* hash */hash$1,
+          /* eq */eq$1
         ];
 }
 
@@ -54,10 +50,8 @@ function hashableU(hash, eq) {
 }
 
 function hashable(hash, eq) {
-  var M_000 = Curry.__1(hash);
-  var M_001 = Curry.__2(eq);
-  var hash$1 = M_000;
-  var eq$1 = M_001;
+  var hash$1 = Curry.__1(hash);
+  var eq$1 = Curry.__2(eq);
   return /* module */[
           /* hash */hash$1,
           /* eq */eq$1