Support yarn workspaces

.yarnrc

@@ -0,0 +1 @@
+workspaces-experimental true

lerna.json

@@ -1,7 +1,8 @@
 {
-  "lerna": "2.0.0-beta.32",
-  "packages": [
-    "packages/*"
-  ],
-  "version": "independent"
-}
+  "lerna": "2.9.0",
+  "packages": ["packages/*"],
+  "npmClient": "yarn",
+  "useWorkspaces": true,
+  "version": "independent",
+  "registry": "https://registry.npmjs.org/"
+}

package.json

@@ -4,17 +4,17 @@
   "devDependencies": {
     "coveralls": "^2.11.2",
     "jest": "^18.1.0",
-    "lerna": "2.0.0-beta.32",
+    "lerna": "2.9.0",
     "prettier": "^1.3.1"
   },
   "repository": {
     "type": "git",
     "url": "https://github.com/pugjs/pug.git"
   },
   "scripts": {
+    "bootstrap": "lerna bootstrap",
     "clean": "lerna clean",
     "release": "lerna publish",
-    "postinstall": "lerna bootstrap",
     "pretest": "lerna run pretest",
     "test": "jest",
     "coverage": "jest --coverage",
@@ -28,5 +28,6 @@
       "./scripts/prettier-javascript-serializer.js"
     ]
   },
-  "license": "MIT"
+  "license": "MIT",
+  "workspaces": ["packages/*"]
 }