new Index() now accepts a computeHash() callback-ish.

packages/xo-collection/package.json

@@ -21,10 +21,10 @@
   ],
   "dependencies": {
     "babel-runtime": "^5",
-    "lodash.bind": "^3.1.0",
-    "lodash.callback": "^3.1.1",
-    "lodash.foreach": "^3.0.2",
-    "make-error": "^1.0.0"
+    "lodash.bind": "^3",
+    "lodash.callback": "^3",
+    "lodash.foreach": "^3",
+    "make-error": "^1"
   },
   "devDependencies": {
     "babel": "^5",

packages/xo-collection/src/index.js

@@ -1,4 +1,5 @@
 import bind from 'lodash.bind'
+import callback from 'lodash.callback'
 
 import clearObject from './clear-object'
 import isEmpty from './is-empty'
@@ -7,7 +8,11 @@ import NotImplemented from './not-implemented'
 // ===================================================================
 
 export default class Index {
-  constructor () {
+  constructor (computeHash) {
+    if (computeHash) {
+      this.computeHash = callback(computeHash)
+    }
+
     this._itemsByHash = Object.create(null)
     this._keysToHash = Object.create(null)
 

packages/xo-collection/src/index.spec.js

@@ -57,8 +57,7 @@ describe('Index', function () {
       col.add(item)
     })
 
-    byGroup = new Index()
-    byGroup.computeHash = item => item.group
+    byGroup = new Index('group')
 
     col.createIndex('byGroup', byGroup)