diff --git a/benchmarks/array.cjs b/benchmarks/array.cjs
new file mode 100644
index 0000000..26ac275
--- /dev/null
+++ b/benchmarks/array.cjs
@@ -0,0 +1,38 @@
+const { Benchmark } = require('benchmark');
+
+const n = 10000;
+
+function Person(name, age) {
+  this.name = name;
+  this.age = age;
+}
+
+new Benchmark.Suite()
+.add('init by constructor', () => {
+  const arr = new Array(n);
+  for (let i = 0; i < n; i++) {
+    arr[i] = new Person(i.toString(), i);
+  }
+})
+.add('init by apply', () => {
+  const arr = Array(n);
+  for (let i = 0; i < n; i++) {
+    arr[i] = new Person(i.toString(), i);
+  }
+})
+.add('init by literal + push', () => {
+  const arr = [];
+  for (let i = 0; i < n; i++) {
+    arr.push(new Person(i.toString(), i));
+  }
+})
+.add('init by literal + assign', () => {
+  const arr = [];
+  for (let i = 0; i < n; i++) {
+    arr[i] = new Person(i.toString(), i);
+  }
+})
+.on('cycle', event => {
+  console.log(event.target.toString());
+})
+.run();
diff --git a/benchmarks/utf8-decode.js b/benchmarks/utf8-decode.cjs
similarity index 77%
rename from benchmarks/utf8-decode.js
rename to benchmarks/utf8-decode.cjs
index 95c3c22..9772877 100644
--- a/benchmarks/utf8-decode.js
+++ b/benchmarks/utf8-decode.cjs
@@ -2,31 +2,31 @@ const { Benchmark } = require('benchmark');
 
 const textDecoder = new TextDecoder();
 
-const utf8DecodeJs = (function (bytes) {
+const utf8DecodeJs = (bytes) => {
   let offset = 0;
-  const end = bytes.length;
+  let end = bytes.length;
 
-  const units = [];
+  let units = [];
   let result = "";
   while (offset < end) {
-    const byte1 = bytes[offset++];
+    let byte1 = bytes[offset++];
     if ((byte1 & 0x80) === 0) {
       // 1 byte
       units.push(byte1);
     } else if ((byte1 & 0xe0) === 0xc0) {
       // 2 bytes
-      const byte2 = bytes[offset++] & 0x3f;
+      let byte2 = bytes[offset++] & 0x3f;
       units.push(((byte1 & 0x1f) << 6) | byte2);
     } else if ((byte1 & 0xf0) === 0xe0) {
       // 3 bytes
-      const byte2 = bytes[offset++] & 0x3f;
-      const byte3 = bytes[offset++] & 0x3f;
+      let byte2 = bytes[offset++] & 0x3f;
+      let byte3 = bytes[offset++] & 0x3f;
       units.push(((byte1 & 0x1f) << 12) | (byte2 << 6) | byte3);
     } else if ((byte1 & 0xf8) === 0xf0) {
       // 4 bytes
-      const byte2 = bytes[offset++] & 0x3f;
-      const byte3 = bytes[offset++] & 0x3f;
-      const byte4 = bytes[offset++] & 0x3f;
+      let byte2 = bytes[offset++] & 0x3f;
+      let byte3 = bytes[offset++] & 0x3f;
+      let byte4 = bytes[offset++] & 0x3f;
       let unit = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0c) | (byte3 << 0x06) | byte4;
       if (unit > 0xffff) {
         unit -= 0x10000;
@@ -49,7 +49,7 @@ const utf8DecodeJs = (function (bytes) {
   }
 
   return result;
-});
+};
 
 const textEncoded = new Uint8Array([0xac, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21]);
 
diff --git a/benchmarks/utf8-encode.cjs b/benchmarks/utf8-encode.cjs
new file mode 100644
index 0000000..2e74719
--- /dev/null
+++ b/benchmarks/utf8-encode.cjs
@@ -0,0 +1,66 @@
+const { Benchmark } = require('benchmark');
+
+const textEncoder = new TextEncoder();
+
+const utf8EncodeJs = (str) => {
+  let strLength = str.length;
+  let output = [];
+  let offset = 0;
+  let pos = 0;
+  while (pos < strLength) {
+    let value = str.charCodeAt(pos++);
+
+    if ((value & 0xffffff80) === 0) {
+      // 1-byte
+      output[offset++] = value;
+      continue;
+    } else if ((value & 0xfffff800) === 0) {
+      // 2-bytes
+      output[offset++] = ((value >> 6) & 0x1f) | 0xc0;
+    } else {
+      // handle surrogate pair
+      if (value >= 0xd800 && value <= 0xdbff) {
+        // high surrogate
+        if (pos < strLength) {
+          let extra = str.charCodeAt(pos);
+          if ((extra & 0xfc00) === 0xdc00) {
+            ++pos;
+            value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;
+          }
+        }
+      }
+
+      if ((value & 0xffff0000) === 0) {
+        // 3-byte
+        output[offset++] = ((value >> 12) & 0x0f) | 0xe0;
+        output[offset++] = ((value >> 6) & 0x3f) | 0x80;
+      } else {
+        // 4-byte
+        output[offset++] = ((value >> 18) & 0x07) | 0xf0;
+        output[offset++] = ((value >> 12) & 0x3f) | 0x80;
+        output[offset++] = ((value >> 6) & 0x3f) | 0x80;
+      }
+    }
+
+    output[offset++] = (value & 0x3f) | 0x80;
+  }
+
+  return new Uint8Array(output);
+}
+
+const text = '안녕, 세상!';
+
+console.log(textEncoder.encode(text));
+console.log(utf8EncodeJs(text));
+
+new Benchmark.Suite()
+.add('TextEncoder', () => {
+  textEncoder.encode(text);
+})
+.add('utf8EncodeJs', () => {
+  utf8EncodeJs(text);
+})
+.on('cycle', event => {
+  console.log(event.target.toString());
+})
+.run();
diff --git a/packages/msgpack/.gitignore b/packages/msgpack/.gitignore
index 12c18d4..6721fa0 100644
--- a/packages/msgpack/.gitignore
+++ b/packages/msgpack/.gitignore
@@ -1 +1,5 @@
+.merlin
+.bsb.lock
+*.bs.js
+
 /lib/
diff --git a/packages/msgpack/bsconfig.json b/packages/msgpack/bsconfig.json
new file mode 100644
index 0000000..2e158ac
--- /dev/null
+++ b/packages/msgpack/bsconfig.json
@@ -0,0 +1,21 @@
+{
+  "name": "@urlpack/msgpack",
+  "sources": [
+    {
+      "dir": "src",
+      "subdirs": true
+    }
+  ],
+  "package-specs": [
+    {
+      "module": "es6",
+      "in-source": true
+    }
+  ],
+  "suffix": ".bs.js",
+  "bs-dependencies": [
+    "rescript-msgpack"
+  ],
+  "bs-dev-dependencies": [
+  ]
+}
diff --git a/packages/msgpack/package.json b/packages/msgpack/package.json
index b480d60..7fa047b 100644
--- a/packages/msgpack/package.json
+++ b/packages/msgpack/package.json
@@ -26,20 +26,25 @@
     "main": "./lib/index.mjs"
   },
   "files": [
-    "src",
-    "lib"
+    "src/**/*.ts",
+    "src/*.res",
+    "lib/*.mjs",
+    "lib/*.cjs",
+    "lib/*.d.ts",
+    "lib/*.map"
   ],
   "scripts": {
     "prepack": "yarn build",
-    "build": "nanobundle build --standalone",
+    "build": "rescript build && nanobundle build --standalone",
     "test": "uvu -r tsm",
     "test:watch": "yarn test || true && watchlist src tests -- yarn test"
   },
   "devDependencies": {
-    "@rescript/std": "^9.1.3",
     "concurrently": "^6.5.1",
     "esbuild": "^0.14.9",
     "nanobundle": "^0.0.21",
+    "rescript": "^9.1.4",
+    "rescript-msgpack": "workspace:^0.1.0",
     "tsm": "^2.2.1",
     "typescript": "^4.5.4",
     "uvu": "^0.5.2",
diff --git a/packages/msgpack/src/decoder.bs.js b/packages/msgpack/src/decoder.bs.js
deleted file mode 100644
index a859c83..0000000
--- a/packages/msgpack/src/decoder.bs.js
+++ /dev/null
@@ -1,564 +0,0 @@
-// Generated by ReScript, PLEASE EDIT WITH CARE
-
-import * as Js_exn from "@rescript/std/lib/es6/js_exn.js";
-import * as Js_dict from "@rescript/std/lib/es6/js_dict.js";
-import * as Pervasives from "@rescript/std/lib/es6/pervasives.js";
-import { timestampDecoder as timestampExt } from "./ext/TimestampDecoder";
-
-var decode2 = (function (_t, bytes) {
-    let offset = 0;
-    const end = bytes.length;
-
-    const units = [];
-    let result = "";
-    while (offset < end) {
-      const byte1 = bytes[offset++];
-      if ((byte1 & 0x80) === 0) {
-        // 1 byte
-        units.push(byte1);
-      } else if ((byte1 & 0xe0) === 0xc0) {
-        // 2 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        units.push(((byte1 & 0x1f) << 6) | byte2);
-      } else if ((byte1 & 0xf0) === 0xe0) {
-        // 3 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        const byte3 = bytes[offset++] & 0x3f;
-        units.push(((byte1 & 0x1f) << 12) | (byte2 << 6) | byte3);
-      } else if ((byte1 & 0xf8) === 0xf0) {
-        // 4 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        const byte3 = bytes[offset++] & 0x3f;
-        const byte4 = bytes[offset++] & 0x3f;
-        let unit = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0c) | (byte3 << 0x06) | byte4;
-        if (unit > 0xffff) {
-          unit -= 0x10000;
-          units.push(((unit >>> 10) & 0x3ff) | 0xd800);
-          unit = 0xdc00 | (unit & 0x3ff);
-        }
-        units.push(unit);
-      } else {
-        units.push(byte1);
-      }
-
-      if (units.length >= 0x1_000) {
-        result += String.fromCharCode(...units);
-        units.length = 0;
-      }
-    }
-
-    if (units.length > 0) {
-      result += String.fromCharCode(...units);
-    }
-
-    return result;
-  });
-
-var $$TextDecoder = {
-  decode2: decode2
-};
-
-var flip64 = (function(binary) {
-  let carry = 1;
-  for (let i = 7; i >= 0; i--) {
-    const v = (binary[i] ^ 0xff) + carry;
-    binary[i] = v & 0xff;
-    carry = v >> 8;
-  }
-});
-
-function make(extensions) {
-  var textDecoder = new TextDecoder();
-  var extensions$1 = Js_dict.fromArray(extensions);
-  return {
-          textDecoder: textDecoder,
-          extensions: extensions$1
-        };
-}
-
-function decode(t, binary) {
-  var extensions = t.extensions;
-  var textDecoder = t.textDecoder;
-  var binary$1 = binary.slice();
-  var view = new DataView(binary$1.buffer);
-  var decode$1 = function (binary, _state, _cursor) {
-    while(true) {
-      var cursor = _cursor;
-      var state = _state;
-      if (typeof state === "number") {
-        var header = view.getUint8(cursor);
-        var cursor$1 = cursor + 1 | 0;
-        if (header < 128) {
-          _cursor = cursor$1;
-          _state = {
-            TAG: /* Done */5,
-            _0: header
-          };
-          continue ;
-        }
-        if (header < 144) {
-          var len = header & 15;
-          _cursor = cursor$1;
-          _state = {
-            TAG: /* DecodeMap */2,
-            _0: len,
-            _1: {}
-          };
-          continue ;
-        }
-        if (header < 160) {
-          var len$1 = header & 15;
-          _cursor = cursor$1;
-          _state = {
-            TAG: /* DecodeArray */1,
-            _0: len$1,
-            _1: new Array(len$1)
-          };
-          continue ;
-        }
-        if (header < 192) {
-          var len$2 = header & 31;
-          _cursor = cursor$1;
-          _state = {
-            TAG: /* DecodeString */0,
-            _0: len$2
-          };
-          continue ;
-        }
-        switch (header) {
-          case 192 :
-              _cursor = cursor$1;
-              _state = {
-                TAG: /* Done */5,
-                _0: null
-              };
-              continue ;
-          case 193 :
-              break;
-          case 194 :
-              _cursor = cursor$1;
-              _state = {
-                TAG: /* Done */5,
-                _0: false
-              };
-              continue ;
-          case 195 :
-              _cursor = cursor$1;
-              _state = {
-                TAG: /* Done */5,
-                _0: true
-              };
-              continue ;
-          case 196 :
-              var len$3 = view.getUint8(cursor$1);
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeBinary */3,
-                _0: len$3
-              };
-              continue ;
-          case 197 :
-              var len$4 = view.getUint16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeBinary */3,
-                _0: len$4
-              };
-              continue ;
-          case 198 :
-              var len$5 = view.getUint32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* DecodeBinary */3,
-                _0: len$5
-              };
-              continue ;
-          case 199 :
-              var len$6 = view.getUint8(cursor$1);
-              var type_ = view.getInt8(cursor$1 + 1 | 0);
-              if (type_ === timestampExt.type) {
-                _cursor = cursor$1 + 2 | 0;
-                _state = {
-                  TAG: /* DecodeExt */4,
-                  _0: len$6,
-                  _1: timestampExt
-                };
-                continue ;
-              }
-              var ext = Js_dict.get(extensions, String(type_));
-              if (ext === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_));
-              }
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: len$6,
-                _1: ext
-              };
-              continue ;
-          case 200 :
-              var len$7 = view.getUint16(cursor$1);
-              var type_$1 = view.getInt8(cursor$1 + 2 | 0);
-              var ext$1 = Js_dict.get(extensions, String(type_$1));
-              if (ext$1 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$1));
-              }
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: len$7,
-                _1: ext$1
-              };
-              continue ;
-          case 201 :
-              var len$8 = view.getUint32(cursor$1);
-              var type_$2 = view.getInt8(cursor$1 + 4 | 0);
-              var ext$2 = Js_dict.get(extensions, String(type_$2));
-              if (ext$2 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$2));
-              }
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: len$8,
-                _1: ext$2
-              };
-              continue ;
-          case 202 :
-              var num = view.getFloat32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num
-              };
-              continue ;
-          case 203 :
-              var num$1 = view.getFloat64(cursor$1);
-              _cursor = cursor$1 + 8 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$1
-              };
-              continue ;
-          case 204 :
-              var num$2 = view.getUint8(cursor$1);
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$2
-              };
-              continue ;
-          case 205 :
-              var num$3 = view.getUint16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$3
-              };
-              continue ;
-          case 206 :
-              var num$4 = view.getUint32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$4
-              };
-              continue ;
-          case 207 :
-              var hi = view.getUint32(cursor$1);
-              var lo = view.getUint32(cursor$1 + 4 | 0);
-              var num$5 = hi * Math.pow(256.0, 4.0) + lo;
-              _cursor = cursor$1 + 8 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$5
-              };
-              continue ;
-          case 208 :
-              var num$6 = view.getInt8(cursor$1);
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$6
-              };
-              continue ;
-          case 209 :
-              var num$7 = view.getInt16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$7
-              };
-              continue ;
-          case 210 :
-              var num$8 = view.getInt32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: num$8
-              };
-              continue ;
-          case 211 :
-              flip64(binary.subarray(cursor$1, cursor$1 + 9 | 0));
-              var hi$1 = view.getUint32(cursor$1);
-              var lo$1 = view.getUint32(cursor$1 + 4 | 0);
-              var num$9 = hi$1 * Math.pow(256.0, 4.0) + lo$1;
-              _cursor = cursor$1 + 8 | 0;
-              _state = {
-                TAG: /* Done */5,
-                _0: 0.0 - num$9
-              };
-              continue ;
-          case 212 :
-              var type_$3 = view.getInt8(cursor$1);
-              var ext$3 = Js_dict.get(extensions, String(type_$3));
-              if (ext$3 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$3));
-              }
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: 1,
-                _1: ext$3
-              };
-              continue ;
-          case 213 :
-              var type_$4 = view.getInt8(cursor$1);
-              var ext$4 = Js_dict.get(extensions, String(type_$4));
-              if (ext$4 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$4));
-              }
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: 2,
-                _1: ext$4
-              };
-              continue ;
-          case 214 :
-              var type_$5 = view.getInt8(cursor$1);
-              if (type_$5 === timestampExt.type) {
-                _cursor = cursor$1 + 1 | 0;
-                _state = {
-                  TAG: /* DecodeExt */4,
-                  _0: 4,
-                  _1: timestampExt
-                };
-                continue ;
-              }
-              var ext$5 = Js_dict.get(extensions, String(type_$5));
-              if (ext$5 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$5));
-              }
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: 4,
-                _1: ext$5
-              };
-              continue ;
-          case 215 :
-              var type_$6 = view.getInt8(cursor$1);
-              if (type_$6 === timestampExt.type) {
-                _cursor = cursor$1 + 1 | 0;
-                _state = {
-                  TAG: /* DecodeExt */4,
-                  _0: 8,
-                  _1: timestampExt
-                };
-                continue ;
-              }
-              var ext$6 = Js_dict.get(extensions, String(type_$6));
-              if (ext$6 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$6));
-              }
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: 8,
-                _1: ext$6
-              };
-              continue ;
-          case 216 :
-              var type_$7 = view.getInt8(cursor$1);
-              var ext$7 = Js_dict.get(extensions, String(type_$7));
-              if (ext$7 === undefined) {
-                return Js_exn.raiseError("Unknown extension type " + String(type_$7));
-              }
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeExt */4,
-                _0: 16,
-                _1: ext$7
-              };
-              continue ;
-          case 217 :
-              var len$9 = view.getUint8(cursor$1);
-              _cursor = cursor$1 + 1 | 0;
-              _state = {
-                TAG: /* DecodeString */0,
-                _0: len$9
-              };
-              continue ;
-          case 218 :
-              var len$10 = view.getUint16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeString */0,
-                _0: len$10
-              };
-              continue ;
-          case 219 :
-              var len$11 = view.getUint32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* DecodeString */0,
-                _0: len$11
-              };
-              continue ;
-          case 220 :
-              var len$12 = view.getUint16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeArray */1,
-                _0: len$12,
-                _1: new Array(len$12)
-              };
-              continue ;
-          case 221 :
-              var len$13 = view.getUint32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* DecodeArray */1,
-                _0: len$13,
-                _1: new Array(len$13)
-              };
-              continue ;
-          case 222 :
-              var len$14 = view.getUint16(cursor$1);
-              _cursor = cursor$1 + 2 | 0;
-              _state = {
-                TAG: /* DecodeMap */2,
-                _0: len$14,
-                _1: {}
-              };
-              continue ;
-          case 223 :
-              var len$15 = view.getUint32(cursor$1);
-              _cursor = cursor$1 + 4 | 0;
-              _state = {
-                TAG: /* DecodeMap */2,
-                _0: len$15,
-                _1: {}
-              };
-              continue ;
-          default:
-
-        }
-        if (header >= 256) {
-          return Js_exn.raiseError("Unknown header " + String(header));
-        }
-        var num$10 = Pervasives.lnot(header ^ 255);
-        _cursor = cursor$1;
-        _state = {
-          TAG: /* Done */5,
-          _0: num$10
-        };
-        continue ;
-      }
-      switch (state.TAG | 0) {
-        case /* DecodeString */0 :
-            var len$16 = state._0;
-            var view$1 = binary.subarray(cursor, cursor + len$16 | 0);
-            var text = decode2(textDecoder, view$1);
-            _cursor = cursor + len$16 | 0;
-            _state = {
-              TAG: /* Done */5,
-              _0: text
-            };
-            continue ;
-        case /* DecodeArray */1 :
-            var array = state._1;
-            var len$17 = state._0;
-            if (len$17 !== 0) {
-              var match = decode$1(binary, /* ExpectHeader */0, cursor);
-              var index = array.length - len$17 | 0;
-              array[index] = match[0];
-              _cursor = match[1];
-              _state = {
-                TAG: /* DecodeArray */1,
-                _0: len$17 - 1 | 0,
-                _1: array
-              };
-              continue ;
-            }
-            _state = {
-              TAG: /* Done */5,
-              _0: array
-            };
-            continue ;
-        case /* DecodeMap */2 :
-            var map = state._1;
-            var len$18 = state._0;
-            if (len$18 !== 0) {
-              var match$1 = decode$1(binary, /* ExpectHeader */0, cursor);
-              var key = match$1[0];
-              if (typeof key !== "string") {
-                return Js_exn.raiseError("Unexpected key type. Expected string, but got " + typeof key);
-              }
-              var match$2 = decode$1(binary, /* ExpectHeader */0, match$1[1]);
-              map[key] = match$2[0];
-              _cursor = match$2[1];
-              _state = {
-                TAG: /* DecodeMap */2,
-                _0: len$18 - 1 | 0,
-                _1: map
-              };
-              continue ;
-            }
-            _state = {
-              TAG: /* Done */5,
-              _0: map
-            };
-            continue ;
-        case /* DecodeBinary */3 :
-            var len$19 = state._0;
-            var copy = binary.slice(cursor, cursor + len$19 | 0);
-            _cursor = cursor + len$19 | 0;
-            _state = {
-              TAG: /* Done */5,
-              _0: copy
-            };
-            continue ;
-        case /* DecodeExt */4 :
-            var len$20 = state._0;
-            var copy$1 = binary.slice(cursor, cursor + len$20 | 0);
-            _cursor = cursor + len$20 | 0;
-            _state = {
-              TAG: /* Done */5,
-              _0: state._1.decode(copy$1, len$20)
-            };
-            continue ;
-        case /* Done */5 :
-            return [
-                    state._0,
-                    cursor
-                  ];
-
-      }
-    };
-  };
-  var match = decode$1(binary$1, /* ExpectHeader */0, 0);
-  var readLength = match[1];
-  var inputLength = binary$1.length;
-  if (inputLength !== readLength) {
-    Js_exn.raiseError("Invalid input length, expected " + String(inputLength) + ", but got " + String(readLength));
-  }
-  return match[0];
-}
-
-export {
-  make ,
-  decode ,
-
-}
diff --git a/packages/msgpack/src/decoder.res b/packages/msgpack/src/decoder.res
index c8f993c..6112888 100644
--- a/packages/msgpack/src/decoder.res
+++ b/packages/msgpack/src/decoder.res
@@ -1,354 +1 @@
-open Js
-open TypedArray2
-
-module TextDecoder = {
-  type t
-
-  @new external make: unit => t = "TextDecoder"
-  @send external decode: (t, Uint8Array.t) => string = "decode"
-
-  /**
-   * Borrowing from https://github.com/msgpack/msgpack-javascript/blob/c58b7e2/src/utils/utf8.ts#L48-L89
-   *
-   * Note:
-   *   The Node.js builtin TextDecoder is seriously slow.
-   *   This custom decoder is 10~12x faster than the builtin
-   *
-   * See benchmarks/utf8-decode.js
-   */
-  let decode2: (t, Uint8Array.t) => string = %raw(`function (_t, bytes) {
-    let offset = 0;
-    const end = bytes.length;
-
-    const units = [];
-    let result = "";
-    while (offset < end) {
-      const byte1 = bytes[offset++];
-      if ((byte1 & 0x80) === 0) {
-        // 1 byte
-        units.push(byte1);
-      } else if ((byte1 & 0xe0) === 0xc0) {
-        // 2 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        units.push(((byte1 & 0x1f) << 6) | byte2);
-      } else if ((byte1 & 0xf0) === 0xe0) {
-        // 3 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        const byte3 = bytes[offset++] & 0x3f;
-        units.push(((byte1 & 0x1f) << 12) | (byte2 << 6) | byte3);
-      } else if ((byte1 & 0xf8) === 0xf0) {
-        // 4 bytes
-        const byte2 = bytes[offset++] & 0x3f;
-        const byte3 = bytes[offset++] & 0x3f;
-        const byte4 = bytes[offset++] & 0x3f;
-        let unit = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0c) | (byte3 << 0x06) | byte4;
-        if (unit > 0xffff) {
-          unit -= 0x10000;
-          units.push(((unit >>> 10) & 0x3ff) | 0xd800);
-          unit = 0xdc00 | (unit & 0x3ff);
-        }
-        units.push(unit);
-      } else {
-        units.push(byte1);
-      }
-
-      if (units.length >= 0x1_000) {
-        result += String.fromCharCode(...units);
-        units.length = 0;
-      }
-    }
-
-    if (units.length > 0) {
-      result += String.fromCharCode(...units);
-    }
-
-    return result;
-  }`)
-}
-
-type result
-external result: 'a => result = "%identity"
-external toString: result => string = "%identity"
-
-@new external makeSizedArray: int => array<result> = "Array"
-
-let flip64: Uint8Array.t => unit = %raw(`function(binary) {
-  let carry = 1;
-  for (let i = 7; i >= 0; i--) {
-    const v = (binary[i] ^ 0xff) + carry;
-    binary[i] = v & 0xff;
-    carry = v >> 8;
-  }
-}`)
-
-type ext = {
-  \"type": int,
-  decode: (. Uint8Array.t, int) => result,
-}
-
-@module("./ext/TimestampDecoder") external timestampExt: ext = "timestamDecoder"
-
-type t = {
-  textDecoder: TextDecoder.t,
-  extensions: Dict.t<ext>,
-}
-
-let make = (~extensions) => {
-  let textDecoder = TextDecoder.make()
-  let extensions = extensions->Js.Dict.fromArray
-  {
-    textDecoder: textDecoder,
-    extensions: extensions,
-  }
-}
-
-type state =
-  | ExpectHeader
-  | DecodeString(int)
-  | DecodeArray(int, array<result>)
-  | DecodeMap(int, Dict.t<result>)
-  | DecodeBinary(int)
-  | DecodeExt(int, ext)
-  | Done(result)
-
-let decode = (t, binary) => {
-  let {textDecoder, extensions} = t
-  let binary = binary->Uint8Array.copy
-  let view = binary->Uint8Array.buffer->DataView.fromBuffer
-  let rec decode = (binary, ~state, ~cursor) => {
-    switch state {
-    | ExpectHeader => {
-        let header = view->DataView.getUint8(cursor)
-        let cursor = cursor + 1
-        switch header {
-        | header if header < 0x80 => binary->decode(~state=Done(header->result), ~cursor)
-        | header if header < 0x90 => {
-            let len = header->land(0xf)
-            binary->decode(~state=DecodeMap(len, Dict.empty()), ~cursor)
-          }
-        | header if header < 0xa0 => {
-            let len = header->land(0xf)
-            binary->decode(~state=DecodeArray(len, makeSizedArray(len)), ~cursor)
-          }
-        | header if header < 0xc0 => {
-            let len = header->land(0x1f)
-            binary->decode(~state=DecodeString(len), ~cursor)
-          }
-        | 0xc0 => binary->decode(~state=Done(null->result), ~cursor)
-        | 0xc2 => binary->decode(~state=Done(false->result), ~cursor)
-        | 0xc3 => binary->decode(~state=Done(true->result), ~cursor)
-        | 0xc4 => {
-            let len = view->DataView.getUint8(cursor)
-            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 1)
-          }
-        | 0xc5 => {
-            let len = view->DataView.getUint16(cursor)
-            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 2)
-          }
-        | 0xc6 => {
-            let len = view->DataView.getUint32(cursor)
-            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 4)
-          }
-        | 0xc7 => {
-            let len = view->DataView.getUint8(cursor)
-            let type_ = view->DataView.getInt8(cursor + 1)
-            if type_ == timestampExt.\"type" {
-              binary->decode(~state=DecodeExt(len, timestampExt), ~cursor=cursor + 2)
-            } else {
-              switch extensions->Dict.get(type_->Belt.Int.toString) {
-              | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 2)
-              | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-              }
-            }
-          }
-        | 0xc8 => {
-            let len = view->DataView.getUint16(cursor)
-            let type_ = view->DataView.getInt8(cursor + 2)
-            switch extensions->Dict.get(type_->Belt.Int.toString) {
-            | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 2)
-            | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-            }
-          }
-        | 0xc9 => {
-            let len = view->DataView.getUint32(cursor)
-            let type_ = view->DataView.getInt8(cursor + 4)
-            switch extensions->Dict.get(type_->Belt.Int.toString) {
-            | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 4)
-            | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-            }
-          }
-        | 0xca => {
-            let num = view->DataView.getFloat32(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 4)
-          }
-        | 0xcb => {
-            let num = view->DataView.getFloat64(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 8)
-          }
-        | 0xcc => {
-            let num = view->DataView.getUint8(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 1)
-          }
-        | 0xcd => {
-            let num = view->DataView.getUint16(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 2)
-          }
-        | 0xce => {
-            let num = view->DataView.getUint32(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 4)
-          }
-        | 0xcf => {
-            let hi = view->DataView.getUint32(cursor)->Belt.Int.toFloat
-            let lo = view->DataView.getUint32(cursor + 4)->Belt.Int.toFloat
-            let num = hi *. Math.pow_float(~base=256.0, ~exp=4.0) +. lo
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 8)
-          }
-        | 0xd0 => {
-            let num = view->DataView.getInt8(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 1)
-          }
-        | 0xd1 => {
-            let num = view->DataView.getInt16(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 2)
-          }
-        | 0xd2 => {
-            let num = view->DataView.getInt32(cursor)
-            binary->decode(~state=Done(num->result), ~cursor=cursor + 4)
-          }
-        | 0xd3 => {
-            binary->Uint8Array.subarray(~start=cursor, ~end_=cursor + 9)->flip64
-            let hi = view->DataView.getUint32(cursor)->Belt.Int.toFloat
-            let lo = view->DataView.getUint32(cursor + 4)->Belt.Int.toFloat
-            let num = hi *. Math.pow_float(~base=256.0, ~exp=4.0) +. lo
-            binary->decode(~state=Done((0.0 -. num)->result), ~cursor=cursor + 8)
-          }
-        | 0xd4 => {
-            let type_ = view->DataView.getInt8(cursor)
-            switch extensions->Dict.get(type_->Belt.Int.toString) {
-            | Some(ext) => binary->decode(~state=DecodeExt(1, ext), ~cursor=cursor + 1)
-            | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-            }
-          }
-        | 0xd5 => {
-            let type_ = view->DataView.getInt8(cursor)
-            switch extensions->Dict.get(type_->Belt.Int.toString) {
-            | Some(ext) => binary->decode(~state=DecodeExt(2, ext), ~cursor=cursor + 1)
-            | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-            }
-          }
-        | 0xd6 => {
-            let type_ = view->DataView.getInt8(cursor)
-            if type_ == timestampExt.\"type" {
-              binary->decode(~state=DecodeExt(4, timestampExt), ~cursor=cursor + 1)
-            } else {
-              switch extensions->Dict.get(type_->Belt.Int.toString) {
-              | Some(ext) => binary->decode(~state=DecodeExt(4, ext), ~cursor=cursor + 1)
-              | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-              }
-            }
-          }
-        | 0xd7 => {
-            let type_ = view->DataView.getInt8(cursor)
-            if type_ == timestampExt.\"type" {
-              binary->decode(~state=DecodeExt(8, timestampExt), ~cursor=cursor + 1)
-            } else {
-              switch extensions->Dict.get(type_->Belt.Int.toString) {
-              | Some(ext) => binary->decode(~state=DecodeExt(8, ext), ~cursor=cursor + 1)
-              | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-              }
-            }
-          }
-        | 0xd8 => {
-            let type_ = view->DataView.getInt8(cursor)
-            switch extensions->Dict.get(type_->Belt.Int.toString) {
-            | Some(ext) => binary->decode(~state=DecodeExt(16, ext), ~cursor=cursor + 1)
-            | None => Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
-            }
-          }
-        | 0xd9 => {
-            let len = view->DataView.getUint8(cursor)
-            binary->decode(~state=DecodeString(len), ~cursor=cursor + 1)
-          }
-        | 0xda => {
-            let len = view->DataView.getUint16(cursor)
-            binary->decode(~state=DecodeString(len), ~cursor=cursor + 2)
-          }
-        | 0xdb => {
-            let len = view->DataView.getUint32(cursor)
-            binary->decode(~state=DecodeString(len), ~cursor=cursor + 4)
-          }
-        | 0xdc => {
-            let len = view->DataView.getUint16(cursor)
-            binary->decode(~state=DecodeArray(len, makeSizedArray(len)), ~cursor=cursor + 2)
-          }
-        | 0xdd => {
-            let len = view->DataView.getUint32(cursor)
-            binary->decode(~state=DecodeArray(len, makeSizedArray(len)), ~cursor=cursor + 4)
-          }
-        | 0xde => {
-            let len = view->DataView.getUint16(cursor)
-            binary->decode(~state=DecodeMap(len, Dict.empty()), ~cursor=cursor + 2)
-          }
-        | 0xdf => {
-            let len = view->DataView.getUint32(cursor)
-            binary->decode(~state=DecodeMap(len, Dict.empty()), ~cursor=cursor + 4)
-          }
-        | header if header < 0x100 => {
-            let num = header->lxor(255)->lnot
-            binary->decode(~state=Done(num->result), ~cursor)
-          }
-        | header => Exn.raiseError(`Unknown header ${header->Belt.Int.toString}`)
-        }
-      }
-    | DecodeString(len) => {
-        let view = binary->Uint8Array.subarray(~start=cursor, ~end_=cursor + len)
-        let text = textDecoder->TextDecoder.decode2(view)
-        binary->decode(~state=Done(text->result), ~cursor=cursor + len)
-      }
-    | DecodeArray(len, array) =>
-      switch len {
-      | 0 => binary->decode(~state=Done(array->result), ~cursor)
-      | len => {
-          let (item, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
-          let index = array->Array2.length - len
-          array->Array2.unsafe_set(index, item)
-          binary->decode(~state=DecodeArray(len - 1, array), ~cursor)
-        }
-      }
-    | DecodeMap(len, map) =>
-      switch len {
-      | 0 => binary->decode(~state=Done(map->result), ~cursor)
-      | len => {
-          let (key, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
-          if typeof(key) == "string" {
-            let (value, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
-            map->Dict.set(key->toString, value)
-            binary->decode(~state=DecodeMap(len - 1, map), ~cursor)
-          } else {
-            Exn.raiseError(`Unexpected key type. Expected string, but got ${typeof(key)}`)
-          }
-        }
-      }
-    | DecodeBinary(len) => {
-        let copy = binary->Uint8Array.slice(~start=cursor, ~end_=cursor + len)
-        binary->decode(~state=Done(copy->result), ~cursor=cursor + len)
-      }
-    | DecodeExt(len, ext) => {
-        let copy = binary->Uint8Array.slice(~start=cursor, ~end_=cursor + len)
-        binary->decode(~state=Done(ext.decode(. copy, len)), ~cursor=cursor + len)
-      }
-    | Done(result) => (result, cursor)
-    }
-  }
-
-  let (result, readLength) = binary->decode(~state=ExpectHeader, ~cursor=0)
-
-  let inputLength = binary->Uint8Array.length
-  if inputLength != readLength {
-    Exn.raiseError(
-      `Invalid input length, expected ${inputLength->Belt.Int.toString}, but got ${readLength->Belt.Int.toString}`,
-    )
-  }
-
-  result
-}
+include RescriptMsgpack.Decoder
diff --git a/packages/msgpack/src/decoder.ts b/packages/msgpack/src/decoder.ts
index d1cf81b..135890b 100644
--- a/packages/msgpack/src/decoder.ts
+++ b/packages/msgpack/src/decoder.ts
@@ -1,5 +1,4 @@
-import type { Input } from './types';
-import type { DecoderExtension } from './ext/types';
+import type { Input, DecoderExtension } from './types';
 
 // @ts-ignore
 import { make as makeDecoder, decode } from './decoder.bs';
diff --git a/packages/msgpack/src/ext/TimestampDecoder.ts b/packages/msgpack/src/ext/TimestampDecoder.ts
deleted file mode 100644
index e3efe8d..0000000
--- a/packages/msgpack/src/ext/TimestampDecoder.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-import type { DecoderExtension } from './types';
-
-export const timestampDecoder: DecoderExtension<Date> = {
-  type: -1,
-  // almost copy-pated from msgpack5's DateCodec implementation
-  // https://github.com/mcollina/msgpack5/blob/master/lib/codecs/DateCodec.js
-  decode(dataArray, byteLength) {
-    let view = new DataView(dataArray.buffer);
-    switch (byteLength) {
-      case 4: {
-        let seconds = view.getUint32(0, false);
-        let millis = seconds / 1000 | 0;
-        return new Date(millis);
-      }
-      case 8: {
-        let upper = view.getUint32(0);
-        let lower = view.getUint32(4);
-        let nanos = upper / 4;
-        let seconds = ((upper & 3) * (2 ** 32)) + lower;
-        let millis = seconds * 1000 + Math.round(nanos / 1e6);
-        return new Date(millis);
-      }
-      case 12:
-        throw new Error(`timestamp96 is not supported yet`);
-      default:
-        throw new Error(`invalid byteLength ${byteLength}`);
-    }
-  },
-};
diff --git a/packages/msgpack/src/ext/TimestampEncoder.ts b/packages/msgpack/src/ext/TimestampEncoder.ts
index cc1e68d..4be80a8 100644
--- a/packages/msgpack/src/ext/TimestampEncoder.ts
+++ b/packages/msgpack/src/ext/TimestampEncoder.ts
@@ -1,4 +1,4 @@
-import type { EncoderExtension } from './types';
+import type { EncoderExtension } from '../types';
 
 let uint64bound = 0x100000000;
 
diff --git a/packages/msgpack/src/ext/types.ts b/packages/msgpack/src/ext/types.ts
deleted file mode 100644
index 46546c4..0000000
--- a/packages/msgpack/src/ext/types.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-export interface EncoderExtension<T extends object> {
-  type: number;
-  check(input: object): input is T;
-  encode(input: T): Uint8Array;
-}
-
-export interface DecoderExtension<T extends object> {
-  type: number;
-  decode(dataArray: Uint8Array, length: number): T;
-}
diff --git a/packages/msgpack/src/index.ts b/packages/msgpack/src/index.ts
index b3d9c23..7f7621b 100644
--- a/packages/msgpack/src/index.ts
+++ b/packages/msgpack/src/index.ts
@@ -1,4 +1,3 @@
 export * from './encoder';
 export * from './decoder';
-
-export type { EncoderExtension, DecoderExtension } from './ext/types';
+export * from './types';
diff --git a/packages/msgpack/src/types.ts b/packages/msgpack/src/types.ts
index 662a669..43cb992 100644
--- a/packages/msgpack/src/types.ts
+++ b/packages/msgpack/src/types.ts
@@ -11,3 +11,14 @@ export type Input<ExtensionType extends object> = (
   | Date
   | ExtensionType
 );
+
+export interface EncoderExtension<T extends object> {
+  type: number;
+  check(input: object): input is T;
+  encode(input: T): Uint8Array;
+}
+
+export interface DecoderExtension<T extends object> {
+  type: number;
+  decode(dataArray: Uint8Array, length: number): T;
+}
diff --git a/packages/rescript-msgpack/.gitignore b/packages/rescript-msgpack/.gitignore
new file mode 100644
index 0000000..6721fa0
--- /dev/null
+++ b/packages/rescript-msgpack/.gitignore
@@ -0,0 +1,5 @@
+.merlin
+.bsb.lock
+*.bs.js
+
+/lib/
diff --git a/packages/rescript-msgpack/README.md b/packages/rescript-msgpack/README.md
new file mode 100644
index 0000000..47b2dd1
--- /dev/null
+++ b/packages/rescript-msgpack/README.md
@@ -0,0 +1 @@
+# rescript-msgpack
diff --git a/packages/rescript-msgpack/bsconfig.json b/packages/rescript-msgpack/bsconfig.json
new file mode 100644
index 0000000..42e73e0
--- /dev/null
+++ b/packages/rescript-msgpack/bsconfig.json
@@ -0,0 +1,21 @@
+{
+  "name": "rescript-msgpack",
+  "namespace": true,
+  "sources": [
+    {
+      "dir": "src",
+      "subdirs": true
+    }
+  ],
+  "package-specs": [
+    {
+      "module": "es6",
+      "in-source": true
+    }
+  ],
+  "suffix": ".bs.js",
+  "bs-dependencies": [
+  ],
+  "bs-dev-dependencies": [
+  ]
+}
diff --git a/packages/rescript-msgpack/package.json b/packages/rescript-msgpack/package.json
new file mode 100644
index 0000000..83130b3
--- /dev/null
+++ b/packages/rescript-msgpack/package.json
@@ -0,0 +1,20 @@
+{
+  "name": "rescript-msgpack",
+  "version": "0.1.0",
+  "packageManager": "yarn@3.1.1",
+  "type": "module",
+  "files": [
+    "src/**/*.res",
+    "src/**/*.resi",
+    "bsconfig.json"
+  ],
+  "scripts": {
+    "build": "rescript build -with-deps"
+  },
+  "peerDependencies": {
+    "rescript": "^9.0.0"
+  },
+  "devDependencies": {
+    "rescript": "^9.1.4"
+  }
+}
diff --git a/packages/rescript-msgpack/src/Decoder.res b/packages/rescript-msgpack/src/Decoder.res
new file mode 100644
index 0000000..94930f1
--- /dev/null
+++ b/packages/rescript-msgpack/src/Decoder.res
@@ -0,0 +1,290 @@
+open Js.TypedArray2
+open Extension
+
+type t = {
+  textDecoder: TextDecoder.t,
+  extensions: Js.Dict.t<module(DecoderExtension)>,
+}
+
+let make = (~extensions=[], ()) => {
+  let textDecoder = TextDecoder.make()
+  let extensions =
+    extensions
+    ->Js.Array2.map((ext: module(DecoderExtension)) => {
+      let module(DecoderExtension) = ext
+      (DecoderExtension.\"type"->Belt.Int.toString, ext)
+    })
+    ->Js.Dict.fromArray
+  {
+    textDecoder: textDecoder,
+    extensions: extensions,
+  }
+}
+
+let flip64: Uint8Array.t => unit = %raw(`binary => {
+  let carry = 1;
+  for (let i = 7; i >= 0; i--) {
+    let v = (binary[i] ^ 0xff) + carry;
+    binary[i] = v & 0xff;
+    carry = v >> 8;
+  }
+}`)
+
+type state =
+  | ExpectHeader
+  | DecodeString(int)
+  | DecodeArray(int, array<Message.t>)
+  | DecodeMap(int, Js.Dict.t<Message.t>)
+  | DecodeBinary(int)
+  | DecodeExt(int, module(DecoderExtension))
+  | Done(Message.t)
+
+let decode = (t, binary) => {
+  let {textDecoder, extensions} = t
+  let binary = binary->Uint8Array.copy
+  let view = binary->Uint8Array.buffer->DataView.fromBuffer
+  let rec decode = (binary, ~state, ~cursor) => {
+    switch state {
+    | ExpectHeader => {
+        let header = view->DataView.getUint8(cursor)
+        let cursor = cursor + 1
+        switch header {
+        | header if header < 0x80 => binary->decode(~state=Done(header->Message.make), ~cursor)
+        | header if header < 0x90 => {
+            let len = header->land(0xf)
+            binary->decode(~state=DecodeMap(len, Js.Dict.empty()), ~cursor)
+          }
+        | header if header < 0xa0 => {
+            let len = header->land(0xf)
+            binary->decode(~state=DecodeArray(len, Message.makeArray(len)), ~cursor)
+          }
+        | header if header < 0xc0 => {
+            let len = header->land(0x1f)
+            binary->decode(~state=DecodeString(len), ~cursor)
+          }
+        | 0xc0 => binary->decode(~state=Done(Js.null->Message.make), ~cursor)
+        | 0xc2 => binary->decode(~state=Done(false->Message.make), ~cursor)
+        | 0xc3 => binary->decode(~state=Done(true->Message.make), ~cursor)
+        | 0xc4 => {
+            let len = view->DataView.getUint8(cursor)
+            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 1)
+          }
+        | 0xc5 => {
+            let len = view->DataView.getUint16(cursor)
+            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 2)
+          }
+        | 0xc6 => {
+            let len = view->DataView.getUint32(cursor)
+            binary->decode(~state=DecodeBinary(len), ~cursor=cursor + 4)
+          }
+        | 0xc7 => {
+            let len = view->DataView.getUint8(cursor)
+            let type_ = view->DataView.getInt8(cursor + 1)
+            if type_ == TimestampDecoder.\"type" {
+              binary->decode(~state=DecodeExt(len, module(TimestampDecoder)), ~cursor=cursor + 2)
+            } else {
+              switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+              | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 2)
+              | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+              }
+            }
+          }
+        | 0xc8 => {
+            let len = view->DataView.getUint16(cursor)
+            let type_ = view->DataView.getInt8(cursor + 2)
+            if type_ == TimestampDecoder.\"type" {
+              binary->decode(~state=DecodeExt(len, module(TimestampDecoder)), ~cursor=cursor + 2)
+            } else {
+              switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+              | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 2)
+              | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+              }
+            }
+          }
+        | 0xc9 => {
+            let len = view->DataView.getUint32(cursor)
+            let type_ = view->DataView.getInt8(cursor + 4)
+            if type_ == TimestampDecoder.\"type" {
+              binary->decode(~state=DecodeExt(len, module(TimestampDecoder)), ~cursor=cursor + 4)
+            } else {
+              switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+              | Some(ext) => binary->decode(~state=DecodeExt(len, ext), ~cursor=cursor + 4)
+              | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+              }
+            }
+          }
+        | 0xca => {
+            let num = view->DataView.getFloat32(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 4)
+          }
+        | 0xcb => {
+            let num = view->DataView.getFloat64(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 8)
+          }
+        | 0xcc => {
+            let num = view->DataView.getUint8(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 1)
+          }
+        | 0xcd => {
+            let num = view->DataView.getUint16(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 2)
+          }
+        | 0xce => {
+            let num = view->DataView.getUint32(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 4)
+          }
+        | 0xcf => {
+            let hi = view->DataView.getUint32(cursor)->Belt.Int.toFloat
+            let lo = view->DataView.getUint32(cursor + 4)->Belt.Int.toFloat
+            let num = hi *. Js.Math.pow_float(~base=256.0, ~exp=4.0) +. lo
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 8)
+          }
+        | 0xd0 => {
+            let num = view->DataView.getInt8(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 1)
+          }
+        | 0xd1 => {
+            let num = view->DataView.getInt16(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 2)
+          }
+        | 0xd2 => {
+            let num = view->DataView.getInt32(cursor)
+            binary->decode(~state=Done(num->Message.make), ~cursor=cursor + 4)
+          }
+        | 0xd3 => {
+            binary->Uint8Array.subarray(~start=cursor, ~end_=cursor + 9)->flip64
+            let hi = view->DataView.getUint32(cursor)->Belt.Int.toFloat
+            let lo = view->DataView.getUint32(cursor + 4)->Belt.Int.toFloat
+            let num = hi *. Js.Math.pow_float(~base=256.0, ~exp=4.0) +. lo
+            binary->decode(~state=Done((0.0 -. num)->Message.make), ~cursor=cursor + 8)
+          }
+        | 0xd4 => {
+            let type_ = view->DataView.getInt8(cursor)
+            switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+            | Some(ext) => binary->decode(~state=DecodeExt(1, ext), ~cursor=cursor + 1)
+            | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+            }
+          }
+        | 0xd5 => {
+            let type_ = view->DataView.getInt8(cursor)
+            switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+            | Some(ext) => binary->decode(~state=DecodeExt(2, ext), ~cursor=cursor + 1)
+            | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+            }
+          }
+        | 0xd6 => {
+            let type_ = view->DataView.getInt8(cursor)
+            if type_ == TimestampDecoder.\"type" {
+              binary->decode(~state=DecodeExt(4, module(TimestampDecoder)), ~cursor=cursor + 1)
+            } else {
+              switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+              | Some(ext) => binary->decode(~state=DecodeExt(4, ext), ~cursor=cursor + 1)
+              | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+              }
+            }
+          }
+        | 0xd7 => {
+            let type_ = view->DataView.getInt8(cursor)
+            if type_ == TimestampDecoder.\"type" {
+              binary->decode(~state=DecodeExt(8, module(TimestampDecoder)), ~cursor=cursor + 1)
+            } else {
+              switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+              | Some(ext) => binary->decode(~state=DecodeExt(8, ext), ~cursor=cursor + 1)
+              | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+              }
+            }
+          }
+        | 0xd8 => {
+            let type_ = view->DataView.getInt8(cursor)
+            switch extensions->Js.Dict.get(type_->Belt.Int.toString) {
+            | Some(ext) => binary->decode(~state=DecodeExt(16, ext), ~cursor=cursor + 1)
+            | None => Js.Exn.raiseError(`Unknown extension type ${type_->Belt.Int.toString}`)
+            }
+          }
+        | 0xd9 => {
+            let len = view->DataView.getUint8(cursor)
+            binary->decode(~state=DecodeString(len), ~cursor=cursor + 1)
+          }
+        | 0xda => {
+            let len = view->DataView.getUint16(cursor)
+            binary->decode(~state=DecodeString(len), ~cursor=cursor + 2)
+          }
+        | 0xdb => {
+            let len = view->DataView.getUint32(cursor)
+            binary->decode(~state=DecodeString(len), ~cursor=cursor + 4)
+          }
+        | 0xdc => {
+            let len = view->DataView.getUint16(cursor)
+            binary->decode(~state=DecodeArray(len, Message.makeArray(len)), ~cursor=cursor + 2)
+          }
+        | 0xdd => {
+            let len = view->DataView.getUint32(cursor)
+            binary->decode(~state=DecodeArray(len, Message.makeArray(len)), ~cursor=cursor + 4)
+          }
+        | 0xde => {
+            let len = view->DataView.getUint16(cursor)
+            binary->decode(~state=DecodeMap(len, Js.Dict.empty()), ~cursor=cursor + 2)
+          }
+        | 0xdf => {
+            let len = view->DataView.getUint32(cursor)
+            binary->decode(~state=DecodeMap(len, Js.Dict.empty()), ~cursor=cursor + 4)
+          }
+        | header if header < 0x100 => {
+            let num = header->lxor(255)->lnot
+            binary->decode(~state=Done(num->Message.make), ~cursor)
+          }
+        | header => Js.Exn.raiseError(`Unknown header ${header->Belt.Int.toString}`)
+        }
+      }
+    | DecodeString(len) => {
+        let view = binary->Uint8Array.subarray(~start=cursor, ~end_=cursor + len)
+        let text = textDecoder->TextDecoder.decode2(view)
+        binary->decode(~state=Done(text->Message.make), ~cursor=cursor + len)
+      }
+    | DecodeArray(len, array) =>
+      switch len {
+      | 0 => binary->decode(~state=Done(array->Message.make), ~cursor)
+      | len => {
+          let (item, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
+          let index = array->Js.Array2.length - len
+          array->Js.Array2.unsafe_set(index, item)
+          binary->decode(~state=DecodeArray(len - 1, array), ~cursor)
+        }
+      }
+    | DecodeMap(len, map) =>
+      switch len {
+      | 0 => binary->decode(~state=Done(map->Message.make), ~cursor)
+      | len => {
+          let (key, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
+          if Js.typeof(key) == "string" {
+            let (value, cursor) = binary->decode(~state=ExpectHeader, ~cursor)
+            map->Js.Dict.set(key->Message.toString, value)
+            binary->decode(~state=DecodeMap(len - 1, map), ~cursor)
+          } else {
+            Js.Exn.raiseError(`Unexpected key type. Expected string, but got ${Js.typeof(key)}`)
+          }
+        }
+      }
+    | DecodeBinary(len) => {
+        let copy = binary->Uint8Array.slice(~start=cursor, ~end_=cursor + len)
+        binary->decode(~state=Done(copy->Message.make), ~cursor=cursor + len)
+      }
+    | DecodeExt(len, module(DecoderExtension)) => {
+        let copy = binary->Uint8Array.slice(~start=cursor, ~end_=cursor + len)
+        binary->decode(~state=Done(DecoderExtension.decode(copy, len)), ~cursor=cursor + len)
+      }
+    | Done(msg) => (msg, cursor)
+    }
+  }
+
+  let (msg, readLength) = binary->decode(~state=ExpectHeader, ~cursor=0)
+
+  let inputLength = binary->Uint8Array.length
+  if inputLength != readLength {
+    Js.Exn.raiseError(
+      `Invalid input length, expected ${inputLength->Belt.Int.toString}, but got ${readLength->Belt.Int.toString}`,
+    )
+  }
+
+  msg
+}
diff --git a/packages/rescript-msgpack/src/Decoder.resi b/packages/rescript-msgpack/src/Decoder.resi
new file mode 100644
index 0000000..39990f9
--- /dev/null
+++ b/packages/rescript-msgpack/src/Decoder.resi
@@ -0,0 +1,8 @@
+type t = {
+  textDecoder: TextDecoder.t,
+  extensions: Js.Dict.t<module(Extension.DecoderExtension)>,
+}
+
+let make: (~extensions: array<module(Extension.DecoderExtension)>=?, unit) => t
+
+let decode: (t, Js.TypedArray2.Uint8Array.t) => Message.t
diff --git a/packages/rescript-msgpack/src/Encoder.res b/packages/rescript-msgpack/src/Encoder.res
new file mode 100644
index 0000000..13b06da
--- /dev/null
+++ b/packages/rescript-msgpack/src/Encoder.res
@@ -0,0 +1,187 @@
+open Extension
+
+type t = {
+  textEncoder: TextEncoder.t,
+  extensions: Js.Dict.t<module(EncoderExtension)>,
+}
+
+let make = (~extensions=[], ()) => {
+  let textEncoder = TextEncoder.make()
+  let extensions =
+    extensions
+    ->Js.Array2.map((ext: module(EncoderExtension)) => {
+      let module(EncoderExtension) = ext
+      (EncoderExtension.\"type"->Belt.Int.toString, ext)
+    })
+    ->Js.Dict.fromArray
+  {
+    textEncoder: textEncoder,
+    extensions: extensions,
+  }
+}
+
+module Obj = {
+  type t = Js.Types.obj_val
+
+  @scope("Array") @val external isArray: t => bool = "isArray"
+
+  external toArray: t => array<'a> = "%identity"
+
+  external toArrayBuffer: t => Js.TypedArray2.ArrayBuffer.t = "%identity"
+
+  external toUint8Array: t => Js.TypedArray2.Uint8Array.t = "%identity"
+
+  external toDict: t => Js.Dict.t<'a> = "%identity"
+}
+
+module Uint8Array = {
+  include Js.TypedArray2.Uint8Array
+
+  external toArrayLike: t => array<elt> = "%identity"
+
+  @inline
+  let setOffset = (t, offset, elt) => {
+    t->unsafe_set(offset, elt)
+    t
+  }
+
+  @inline
+  let setOffsetA = (t, offset, arr) => {
+    t->setArrayOffset(arr->toArrayLike, offset)
+    t
+  }
+}
+
+type state =
+  | ExpectValue
+  | EncodeInt(int)
+  | EncodeFloat(float)
+  | EncodeString(string)
+  | EncodeBinary(Uint8Array.t)
+  | EncodeArray(int, array<Message.t>)
+  | EncodeMap(int, array<(string, Message.t)>)
+  | Done(Uint8Array.t)
+
+let encode = (t, msg) => {
+  let {textEncoder, extensions} = t
+
+  let rec encode = (msg, ~state) => {
+    open Uint8Array
+
+    switch state {
+    | ExpectValue =>
+      switch msg->Message.toJSON->Js.Types.classify {
+      | JSNull => msg->encode(~state=Done(make([0xc0])))
+      | JSFalse => msg->encode(~state=Done(make([0xc2])))
+      | JSTrue => msg->encode(~state=Done(make([0xc3])))
+      | JSNumber(number) if %raw(`number % 1 > 0`) => msg->encode(~state=EncodeFloat(number))
+      | JSNumber(number) if -2147483648.0 <= number && number <= 2147483647.0 =>
+        msg->encode(~state=EncodeInt(number->Belt.Float.toInt))
+      | JSNumber(_) => Js.Exn.raiseError(`Only support int32 range yet`)
+      | JSString(string) => msg->encode(~state=EncodeString(string))
+      | JSObject(object) if object->Obj.isArray => {
+          let array = object->Obj.toArray
+          let len = array->Belt.Array.length
+          msg->encode(~state=EncodeArray(len, array))
+        }
+      | JSObject(object) if %raw(`object instanceof Uint8Array`) => {
+          let binary = object->Obj.toUint8Array
+          msg->encode(~state=EncodeBinary(binary))
+        }
+      | JSObject(object) if %raw(`object instanceof ArrayBuffer`) => {
+          let binary = object->Obj.toArrayBuffer->Uint8Array.fromBuffer
+          msg->encode(~state=EncodeBinary(binary))
+        }
+      | JSObject(object) if object->TimestampEncoder.check => msg->encode(
+          ~state=Done(object->TimestampEncoder.encode),
+        )
+      | JSObject(object) =>
+        switch extensions->Js.Dict.get(TimestampEncoder.\"type"->Belt.Int.toString) {
+        | Some(module(EncoderExtension)) =>
+          msg->encode(~state=Done(object->EncoderExtension.encode))
+        | None => {
+            let entries = object->Obj.toDict->Js.Dict.entries
+            let len = entries->Belt.Array.length
+            msg->encode(~state=EncodeMap(len, entries))
+          }
+        }
+      | _ => msg->encode(~state=Done(fromLength(0)))
+      }
+    | EncodeInt(value) if value == 0 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if 0 < value && value < 128 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if 128 <= value && value < 256 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if 256 <= value && value < 65536 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if 65536 <= value => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if 0 > value && value >= -32 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if -32 > value && value >= -128 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if -128 > value && value >= -32768 => msg->encode(~state=Done(make([0])))
+    | EncodeInt(value) if -32768 > value => msg->encode(~state=Done(make([0])))
+    | EncodeFloat(value) => {
+        open Js.TypedArray2
+        let is64 = value->Js.Math.fround != value
+        let array = fromLength(is64 ? 9 : 5)
+        let view = DataView.fromBuffer(array->buffer)
+        if is64 {
+          array->unsafe_set(0, 0xcb)
+          view->DataView.setFloat64(1, value)
+        } else {
+          array->unsafe_set(0, 0xca)
+          view->DataView.setFloat32(1, value)
+        }
+        msg->encode(~state=Done(array))
+      }
+    | EncodeString(value) => {
+        let buffer = textEncoder->TextEncoder.encode2(value)
+        let len = buffer->length
+        let binary = switch len {
+        | len if len < 32 =>
+          fromLength(len + 1)->setOffset(0, len->lor(0xa0))->setOffsetA(1, buffer)
+        | len if len < 256 =>
+          fromLength(len + 2)->setOffset(0, 0xd9)->setOffset(1, len)->setOffsetA(2, buffer)
+        | len if len < 65536 =>
+          fromLength(len + 3)
+          ->setOffset(0, 0xda)
+          ->setOffset(1, len->lsr(8)->land(0xff))
+          ->setOffset(2, len->land(0xff))
+          ->setOffsetA(3, buffer)
+        | len if Belt.Int.toFloat(len) < 4294967296.0 =>
+          fromLength(len + 5)
+          ->setOffset(0, 0xdb)
+          ->setOffset(1, len->lsr(24)->land(0xff))
+          ->setOffset(2, len->lsr(16)->land(0xff))
+          ->setOffset(3, len->lsr(8)->land(0xff))
+          ->setOffset(4, len->land(0xff))
+          ->setOffsetA(5, buffer)
+        | _ => fromLength(0)
+        }
+        msg->encode(~state=Done(binary))
+      }
+    | EncodeBinary(value) => {
+        let len = value->Uint8Array.length
+        let binary = switch len {
+        | len if len < 256 =>
+          fromLength(len + 2)->setOffset(0, 0xc4)->setOffset(1, len)->setOffsetA(2, value)
+        | len if len < 65536 =>
+          fromLength(len + 3)
+          ->setOffset(0, 0xc5)
+          ->setOffset(1, len->lsr(8))
+          ->setOffset(2, len->land(0xff))
+          ->setOffsetA(3, value)
+        | len if len->Belt.Int.toFloat < 4294967296.0 =>
+          fromLength(len + 5)
+          ->setOffset(0, 0xc6)
+          ->setOffset(1, len->lsr(24)->land(0xff))
+          ->setOffset(2, len->lsr(16)->land(0xff))
+          ->setOffset(3, len->lsr(8)->land(0xff))
+          ->setOffset(4, len->land(0xff))
+          ->setOffsetA(5, value)
+        | _ => fromLength(0)
+        }
+        msg->encode(~state=Done(binary))
+      }
+    | Done(binary) => binary
+    }
+  }
+
+  msg->encode(~state=ExpectValue)
+}
diff --git a/packages/rescript-msgpack/src/Encoder.resi b/packages/rescript-msgpack/src/Encoder.resi
new file mode 100644
index 0000000..6458b7f
--- /dev/null
+++ b/packages/rescript-msgpack/src/Encoder.resi
@@ -0,0 +1,8 @@
+type t = {
+  textEncoder: TextEncoder.t,
+  extensions: Js.Dict.t<module(Extension.EncoderExtension)>,
+}
+
+let make: (~extensions: array<module(Extension.EncoderExtension)>=?, unit) => t
+
+let encode: (t, Message.t) => Js.TypedArray2.Uint8Array.t
diff --git a/packages/rescript-msgpack/src/Extension.res b/packages/rescript-msgpack/src/Extension.res
new file mode 100644
index 0000000..476ffe9
--- /dev/null
+++ b/packages/rescript-msgpack/src/Extension.res
@@ -0,0 +1,13 @@
+module type EncoderExtension = {
+  let \"type": int
+
+  let check: Js.Types.obj_val => bool
+
+  let encode: Js.Types.obj_val => Js.TypedArray2.Uint8Array.t
+}
+
+module type DecoderExtension = {
+  let \"type": int
+
+  let decode: (Js.TypedArray2.Uint8Array.t, int) => Message.t
+}
diff --git a/packages/rescript-msgpack/src/Message.res b/packages/rescript-msgpack/src/Message.res
new file mode 100644
index 0000000..578eae3
--- /dev/null
+++ b/packages/rescript-msgpack/src/Message.res
@@ -0,0 +1,13 @@
+type t
+
+external make: 'a => t = "%identity"
+
+@val external makeArray: int => array<t> = "Array"
+
+external toString: t => string = "%identity"
+
+external toInt: t => int = "%identity"
+
+external toFloat: t => float = "%identity"
+
+external toJSON: t => Js.Json.t = "%identity"
diff --git a/packages/rescript-msgpack/src/TextDecoder.res b/packages/rescript-msgpack/src/TextDecoder.res
new file mode 100644
index 0000000..a2cbdaf
--- /dev/null
+++ b/packages/rescript-msgpack/src/TextDecoder.res
@@ -0,0 +1,64 @@
+open Js.TypedArray2
+
+type t
+
+@new external make: unit => t = "TextDecoder"
+@send external decode: (t, Uint8Array.t) => string = "decode"
+
+/**
+ * Borrowing from https://github.com/msgpack/msgpack-javascript/blob/c58b7e2/src/utils/utf8.ts#L110-L157
+ *
+ * Note:
+ *   The Node.js builtin TextDecoder is seriously slow.
+ *   This custom decoder is 10~12x faster than the builtin
+ *
+ * See benchmarks/utf8-decode.cjs
+ */
+let decode2: (t, Uint8Array.t) => string = %raw(`(_t, bytes) => {
+  let offset = 0;
+  let end = bytes.length;
+
+  let units = [];
+  let result = "";
+  while (offset < end) {
+    let byte1 = bytes[offset++];
+    if ((byte1 & 0x80) === 0) {
+      // 1 byte
+      units.push(byte1);
+    } else if ((byte1 & 0xe0) === 0xc0) {
+      // 2 bytes
+      let byte2 = bytes[offset++] & 0x3f;
+      units.push(((byte1 & 0x1f) << 6) | byte2);
+    } else if ((byte1 & 0xf0) === 0xe0) {
+      // 3 bytes
+      let byte2 = bytes[offset++] & 0x3f;
+      let byte3 = bytes[offset++] & 0x3f;
+      units.push(((byte1 & 0x1f) << 12) | (byte2 << 6) | byte3);
+    } else if ((byte1 & 0xf8) === 0xf0) {
+      // 4 bytes
+      let byte2 = bytes[offset++] & 0x3f;
+      let byte3 = bytes[offset++] & 0x3f;
+      let byte4 = bytes[offset++] & 0x3f;
+      let unit = ((byte1 & 0x07) << 0x12) | (byte2 << 0x0c) | (byte3 << 0x06) | byte4;
+      if (unit > 0xffff) {
+        unit -= 0x10000;
+        units.push(((unit >>> 10) & 0x3ff) | 0xd800);
+        unit = 0xdc00 | (unit & 0x3ff);
+      }
+      units.push(unit);
+    } else {
+      units.push(byte1);
+    }
+
+    if (units.length >= 0x1_000) {
+      result += String.fromCharCode(...units);
+      units.length = 0;
+    }
+  }
+
+  if (units.length > 0) {
+    result += String.fromCharCode(...units);
+  }
+
+  return result;
+}`)
diff --git a/packages/rescript-msgpack/src/TextEncoder.res b/packages/rescript-msgpack/src/TextEncoder.res
new file mode 100644
index 0000000..08831e2
--- /dev/null
+++ b/packages/rescript-msgpack/src/TextEncoder.res
@@ -0,0 +1,61 @@
+open Js.TypedArray2
+
+type t
+
+@new external make: unit => t = "TextEncoder"
+@send external encode: (t, string) => Uint8Array.t = "encode"
+
+/**
+ * Borrowing from https://github.com/msgpack/msgpack-javascript/blob/c58b7e2/src/utils/utf8.ts#L48-L89
+ *
+ * Note:
+ *   The Node.js builtin TextEncoder is seriously slow.
+ *   This custom decoder is ~5x faster than the builtin
+ *
+ * See benchmarks/utf8-encode.cjs
+ */
+let encode2: (t, string) => Uint8Array.t = %raw(`(_t, str) => {
+  let strLength = str.length;
+  let output = [];
+  let offset = 0;
+  let pos = 0;
+  while (pos < strLength) {
+    let value = str.charCodeAt(pos++);
+
+    if ((value & 0xffffff80) === 0) {
+      // 1-byte
+      output[offset++] = value;
+      continue;
+    } else if ((value & 0xfffff800) === 0) {
+      // 2-bytes
+      output[offset++] = ((value >> 6) & 0x1f) | 0xc0;
+    } else {
+      // handle surrogate pair
+      if (value >= 0xd800 && value <= 0xdbff) {
+        // high surrogate
+        if (pos < strLength) {
+          let extra = str.charCodeAt(pos);
+          if ((extra & 0xfc00) === 0xdc00) {
+            ++pos;
+            value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;
+          }
+        }
+      }
+
+      if ((value & 0xffff0000) === 0) {
+        // 3-byte
+        output[offset++] = ((value >> 12) & 0x0f) | 0xe0;
+        output[offset++] = ((value >> 6) & 0x3f) | 0x80;
+      } else {
+        // 4-byte
+        output[offset++] = ((value >> 18) & 0x07) | 0xf0;
+        output[offset++] = ((value >> 12) & 0x3f) | 0x80;
+        output[offset++] = ((value >> 6) & 0x3f) | 0x80;
+      }
+    }
+
+    output[offset++] = (value & 0x3f) | 0x80;
+  }
+
+  return new Uint8Array(output);
+}`)
diff --git a/packages/rescript-msgpack/src/TimestampDecoder.res b/packages/rescript-msgpack/src/TimestampDecoder.res
new file mode 100644
index 0000000..19cc2f4
--- /dev/null
+++ b/packages/rescript-msgpack/src/TimestampDecoder.res
@@ -0,0 +1,26 @@
+let \"type" = -1
+
+// almost copy-pated from msgpack5's DateCodec implementation
+// https://github.com/mcollina/msgpack5/blob/master/lib/codecs/DateCodec.js
+let decode: (Js.TypedArray2.Uint8Array.t, int) => Message.t = %raw(`(array, byteLength) => {
+  let view = new DataView(array.buffer);
+  switch (byteLength) {
+    case 4: {
+      let seconds = view.getUint32(0, false);
+      let millis = seconds / 1000 | 0;
+      return new Date(millis);
+    }
+    case 8: {
+      let upper = view.getUint32(0);
+      let lower = view.getUint32(4);
+      let nanos = upper / 4;
+      let seconds = ((upper & 3) * (2 ** 32)) + lower;
+      let millis = seconds * 1000 + Math.round(nanos / 1e6);
+      return new Date(millis);
+    }
+    case 12:
+      throw new Error('timestamp96 is not supported yet');
+    default:
+      throw new Error('invalid byteLength ' + byteLength);
+  }
+}`)
diff --git a/packages/rescript-msgpack/src/TimestampEncoder.res b/packages/rescript-msgpack/src/TimestampEncoder.res
new file mode 100644
index 0000000..c2b08b2
--- /dev/null
+++ b/packages/rescript-msgpack/src/TimestampEncoder.res
@@ -0,0 +1,33 @@
+let \"type" = -1
+
+let check: Js.Types.obj_val => bool = %raw(`x => x instanceof Date`)
+
+let encode: Js.Types.obj_val => Js.TypedArray2.Uint8Array.t = %raw(`obj => {
+  let uint64bound = 0x100000000;
+
+  let millis = obj.getTime();
+  let seconds = millis / 1000 | 0;
+  let nanos = (millis - (seconds * 1000)) * 1e6;
+  let bound = uint64bound - 1;
+
+  if (nanos || seconds > bound) {
+    let array = new Uint8Array(10);
+    let view = new DataView(array.buffer);
+    let upperNanos = nanos * 4;
+    let upperSeconds = seconds / uint64bound;
+    let upper = (upperNanos + upperSeconds) & bound;
+    let lower = seconds & bound;
+    view.setUint8(0, 0xd7);
+    view.setInt8(1, -1);
+    view.setUint32(2, upper, false);
+    view.setUint32(6, lower, false);
+    return array;
+  } else {
+    let array = new Uint8Array(6);
+    let view = new DataView(array.buffer);
+    view.setUint8(0, 0xd6);
+    view.setInt8(1, -1);
+    view.setUint32(2, millis / 1000 | 0, false);
+    return array;
+  }
+}`)
diff --git a/yarn.lock b/yarn.lock
index 81ebd96..9789f1b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -345,13 +345,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@rescript/std@npm:^9.1.3":
-  version: 9.1.3
-  resolution: "@rescript/std@npm:9.1.3"
-  checksum: 100055c97210c4dcdef7606807f7d5f4e305f0ec6d2da74111d9993653d43fc5322318fec9a57be668f9770c42af139bf6347f870d95daa3a46cdf37b34aae8d
-  languageName: node
-  linkType: hard
-
 "@tootallnate/once@npm:1":
   version: 1.1.2
   resolution: "@tootallnate/once@npm:1.1.2"
@@ -458,10 +451,11 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@urlpack/msgpack@workspace:packages/msgpack"
   dependencies:
-    "@rescript/std": ^9.1.3
     concurrently: ^6.5.1
     esbuild: ^0.14.9
     nanobundle: ^0.0.21
+    rescript: ^9.1.4
+    rescript-msgpack: "workspace:^0.1.0"
     tsm: ^2.2.1
     typescript: ^4.5.4
     uvu: ^0.5.2
@@ -2823,6 +2817,28 @@ __metadata:
   languageName: node
   linkType: hard
 
+"rescript-msgpack@workspace:^0.1.0, rescript-msgpack@workspace:packages/rescript-msgpack":
+  version: 0.0.0-use.local
+  resolution: "rescript-msgpack@workspace:packages/rescript-msgpack"
+  dependencies:
+    rescript: ^9.1.4
+  peerDependencies:
+    rescript: ^9.0.0
+  languageName: unknown
+  linkType: soft
+
+"rescript@npm:^9.1.4":
+  version: 9.1.4
+  resolution: "rescript@npm:9.1.4"
+  bin:
+    bsc: bsc
+    bsrefmt: bsrefmt
+    bstracing: lib/bstracing
+    rescript: rescript
+  checksum: 3c503580f968b4d4409830093c57f85b5590f7372250345427b3a7c1f5ccb08009e1edd89b4a3dcbb3ee95ee4dcad9c337ece4d1f8fdaa10e22ed04b8a7495c0
+  languageName: node
+  linkType: hard
+
 "resolve-from@npm:^5.0.0":
   version: 5.0.0
   resolution: "resolve-from@npm:5.0.0"