diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000000..adacf9ebe1
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,80 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    steps:
+      - uses: actions/setup-node@v1.4.2
+        with:
+          node-version: 12
+      - uses: actions/checkout@v2.2.0
+      - name: Install esy
+        run: npm install -g esy
+        
+      - name: Try to restore install cache
+        uses: actions/cache@v2
+        with:
+          path: ~/.esy/source
+          key: source-${{ hashFiles('**/index.json') }}
+
+      - name: Clone submodules
+        run: git submodule update --init
+
+      - name: Install
+        run: esy install
+
+      - name: Print esy cache
+        uses: actions/github-script@v2
+        id: print_esy_cache
+        with:
+          script: |
+            const path = require('path')
+            const scriptPath = path.resolve('.github/workflows/print_esy_cache.js')
+            require(scriptPath)(core)
+
+      - name: Try to restore build cache
+        id: deps-cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.print_esy_cache.outputs.esy_cache }}
+          key: build-${{ matrix.os }}-${{ hashFiles('**/index.json') }}
+          restore-keys: build-${{ matrix.os }}-
+
+      # Here we use a low-level. In real situation you don't have to
+      # but it is useful in CI as it split the log in GitHub UI.
+      # You can see at a glance if it is your projet or your deps that break.
+      #
+      # We also use --release flag to build less.
+      # This allow us to spo syntax/type error more quickly.
+      - name: Build release dependencies
+        if: steps.deps-cache.outputs.cache-hit != 'true'
+        run: esy build-dependencies --release
+
+      - name: Build project in release
+        run: esy build --release
+
+      # Now that our core project build let builds others deps
+      - name: Build  dependencies
+        if: steps.deps-cache.outputs.cache-hit != 'true'
+        run: esy build-dependencies
+
+      - name: Build project
+        run: esy build
+
+      # Here we cleanup if we have a cache fail because we use restore-keys.
+      # restore-keys take the old store even on cache fail.
+      # So, we have deps we don't care anymore. We prune them.
+      - name: Clean global store
+        if: steps.deps-cache.outputs.cache-hit != 'true'
+        run: esy cleanup .
+
+      - name: Test
+        run: esy test
+
+      - name: Build docs
+        run: esy doc
diff --git a/.github/workflows/print_esy_cache.js b/.github/workflows/print_esy_cache.js
new file mode 100644
index 0000000000..a1498fe5db
--- /dev/null
+++ b/.github/workflows/print_esy_cache.js
@@ -0,0 +1,14 @@
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+
+const ESY_FOLDER = process.env.ESY__PREFIX
+  ? process.env.ESY__PREFIX
+  : path.join(os.homedir(), ".esy");
+const esy3 = fs
+  .readdirSync(ESY_FOLDER)
+  .filter(name => name.length > 0 && name[0] === "3")
+  .sort()
+  .pop();
+module.exports = exports = core =>
+    core.setOutput('esy_cache', path.join(ESY_FOLDER, esy3, "i"));
diff --git a/4061.json b/4061.json
deleted file mode 100644
index b5dfd6c8f5..0000000000
--- a/4061.json
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  "source": "./esy.json",
-  "override": {
-    "resolutions": {
-      "ocaml": "ulrikstrid/ocaml:package.json#68e181a3a44f0b6be1b1ab1e585d2c9f2718c37b"
-    }
-  }
-}
diff --git a/esy.json b/esy.json
index 42db6276a1..a1fff09e6d 100644
--- a/esy.json
+++ b/esy.json
@@ -1,6 +1,6 @@
 {
   "name": "bs-platform",
-  "version": "7.2.0",
+  "version": "8.3.0-dev.2",
   "dependencies": {
     "ocaml": "4.6.1000+BS"
   },
@@ -8,13 +8,14 @@
     "ocaml": "4.6.1000+BS"
   },
   "resolutions": {
-    "ocaml": "bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400"
+    "ocaml": "Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57"
   },
   "scripts": {
+    "doc": "echo here we can generate doc for rescript-lang and push",
+    "test": "echo here we can actually test the binary work maybe with bsc -e 'code'",
     "clean": "node ./scripts/ninja.js clean"
   },
   "esy": {
-    "buildsInSource": true,
     "build": [
       ["node", "./scripts/install.js"],
       ["cp", "-r", "-f", "#{self.root / 'bsconfig.json'}", "#{self.install}"],
diff --git a/esy.lock/index.json b/esy.lock/index.json
index f609241030..b485fbb55a 100644
--- a/esy.lock/index.json
+++ b/esy.lock/index.json
@@ -1,17 +1,17 @@
 {
-  "checksum": "3c8b1af980087634890b5cb0aea5b450",
+  "checksum": "8dea6b83c2d82cbe9271b3aa8aa6ca2a",
   "root": "bs-platform@link-dev:./esy.json",
   "node": {
-    "ocaml@github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400@d41d8cd9": {
+    "ocaml@github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57@d41d8cd9": {
       "id":
-        "ocaml@github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400@d41d8cd9",
+        "ocaml@github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57@d41d8cd9",
       "name": "ocaml",
       "version":
-        "github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400",
+        "github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57",
       "source": {
         "type": "install",
         "source": [
-          "github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400"
+          "github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57"
         ]
       },
       "overrides": [],
@@ -25,10 +25,10 @@
       "source": { "type": "link-dev", "path": ".", "manifest": "esy.json" },
       "overrides": [],
       "dependencies": [
-        "ocaml@github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400@d41d8cd9"
+        "ocaml@github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57@d41d8cd9"
       ],
       "devDependencies": [
-        "ocaml@github:bucklescript/ocaml:package.json#bf88fbf88d4e305bab82259def35a4492e475400@d41d8cd9"
+        "ocaml@github:Et7f3/ocaml:package.json#cee7129b58afcb987cc1741acf4a786414502a57@d41d8cd9"
       ]
     }
   }
diff --git a/scripts/ninja.js b/scripts/ninja.js
index bded5701e1..312bbd4d2d 100755
--- a/scripts/ninja.js
+++ b/scripts/ninja.js
@@ -1415,6 +1415,10 @@ build all: phony runtime others $stdlib test
 `
     );
   } else {
+    // ASK: should I change something in the other branch ?
+    // ASK: Do you want a less destructive way by generating a .ninja file to include
+    const snapshot_ninja = fs.readFileSync(path.join(jscompDir, "snapshot.ninja"), "utf8");
+    fs.writeFileSync(path.join(jscompDir, "snapshot.ninja"), snapshot_ninja.replace(/^native_ocaml_path.*/m, "native_ocaml_path = " + (process.env.ESY === "true" ? path.join(process.env.OCAMLLIB, "/../..") : "../ocaml/")), "utf8");
     writeFileAscii(
       path.join(jscompDir, "build.ninja"),
       `