Bump to v3.7.0.

README.md

@@ -1,4 +1,4 @@
-# lodash v3.5.0
+# lodash v3.7.0
 
 The [modern build](https://github.com/lodash/lodash/wiki/Build-Differences) of [lodash](https://lodash.com/) exported as [Node.js](http://nodejs.org/)/[io.js](https://iojs.org/) modules.
 
@@ -28,7 +28,7 @@ var array = require('lodash/array');
 var chunk = require('lodash/array/chunk');
 ```
 
-See the [package source](https://github.com/lodash/lodash/tree/3.5.0-npm) for more details.
+See the [package source](https://github.com/lodash/lodash/tree/3.7.0-npm) for more details.
 
 **Note:**<br>
 Don’t assign values to the [special variable](http://nodejs.org/api/repl.html#repl_repl_features) `_` when in the REPL.<br>
@@ -39,8 +39,8 @@ Install [n_](https://www.npmjs.com/package/n_) for a REPL that includes lodash b
 lodash is also available in a variety of other builds & module formats.
 
  * npm packages for [modern](https://www.npmjs.com/package/lodash), [compatibility](https://www.npmjs.com/package/lodash-compat), & [per method](https://www.npmjs.com/browse/keyword/lodash-modularized) builds
- * AMD modules for [modern](https://github.com/lodash/lodash/tree/3.5.0-amd) & [compatibility](https://github.com/lodash/lodash-compat/tree/3.5.0-amd) builds
- * ES modules for the [modern](https://github.com/lodash/lodash/tree/3.5.0-es) build
+ * AMD modules for [modern](https://github.com/lodash/lodash/tree/3.7.0-amd) & [compatibility](https://github.com/lodash/lodash-compat/tree/3.7.0-amd) builds
+ * ES modules for the [modern](https://github.com/lodash/lodash/tree/3.7.0-es) build
 
 ## Further Reading
 
@@ -51,7 +51,7 @@ lodash is also available in a variety of other builds & module formats.
   * [Roadmap](https://github.com/lodash/lodash/wiki/Roadmap)
   * [More Resources](https://github.com/lodash/lodash/wiki/Resources)
 
-## Features *not* in Underscore
+## Features
 
  * ~100% [code coverage](https://coveralls.io/r/lodash)
  * Follows [semantic versioning](http://semver.org/) for releases
@@ -75,20 +75,22 @@ lodash is also available in a variety of other builds & module formats.
  * [_.forEach](https://lodash.com/docs#forEach) supports exiting early
  * [_.forIn](https://lodash.com/docs#forIn) for iterating all enumerable properties
  * [_.forOwn](https://lodash.com/docs#forOwn) for iterating own properties
+ * [_.get](https://lodash.com/docs#get) & [_.set](https://lodash.com/docs#set) for deep property getting & setting
  * [_.inRange](https://lodash.com/docs#inRange) for checking whether a number is within a given range
  * [_.isNative](https://lodash.com/docs#isNative) to check for native functions
  * [_.isPlainObject](https://lodash.com/docs#isPlainObject) & [_.toPlainObject](https://lodash.com/docs#toPlainObject) to check for & convert to `Object` objects
  * [_.isTypedArray](https://lodash.com/docs#isTypedArray) to check for typed arrays
  * [_.matches](https://lodash.com/docs#matches) supports deep object comparisons
  * [_.matchesProperty](https://lodash.com/docs#matchesProperty) to complement [_.matches](https://lodash.com/docs#matches) & [_.property](https://lodash.com/docs#property)
+ * [_.method](https://lodash.com/docs#method) & [_.methodOf](https://lodash.com/docs#methodOf) to create functions that invoke methods
  * [_.merge](https://lodash.com/docs#merge) for a deep [_.extend](https://lodash.com/docs#extend)
  * [_.parseInt](https://lodash.com/docs#parseInt) for consistent cross-environment behavior
  * [_.pull](https://lodash.com/docs#pull), [_.pullAt](https://lodash.com/docs#pullAt), & [_.remove](https://lodash.com/docs#remove) for mutating arrays
  * [_.random](https://lodash.com/docs#random) supports returning floating-point numbers
+ * [_.restParam](https://lodash.com/docs#restParam) & [_.spread](https://lodash.com/docs#spread) for applying rest parameters & spreading arguments to functions
  * [_.runInContext](https://lodash.com/docs#runInContext) for collisionless mixins & easier mocking
  * [_.slice](https://lodash.com/docs#slice) for creating subsets of array-like values
  * [_.sortByAll](https://lodash.com/docs#sortByAll) & [_.sortByOrder](https://lodash.com/docs#sortByOrder) for sorting by multiple properties & orders
- * [_.spread](https://lodash.com/docs#spread) for creating a function to spread an array of arguments to another
  * [_.sum](https://lodash.com/docs#sum) to get the sum of values
  * [_.support](https://lodash.com/docs#support) for flagging environment features
  * [_.template](https://lodash.com/docs#template) supports [*“imports”*](https://lodash.com/docs#templateSettings-imports) options & [ES template delimiters](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-template-literal-lexical-components)
@@ -112,5 +114,5 @@ lodash is also available in a variety of other builds & module formats.
 
 ## Support
 
-Tested in Chrome 40-41, Firefox 35-36, IE 6-11, Opera 26-27, Safari 5-8, io.js 1.5.0, Node.js 0.8.28, 0.10.36, & 0.12.0, PhantomJS 1.9.8, RingoJS 0.11, & Rhino 1.7RC5.
+Tested in Chrome 41-42, Firefox 36-37, IE 6-11, Opera 27-28, Safari 5-8, io.js 1.7.1, Node.js 0.8.28, 0.10.38, & 0.12.2, PhantomJS 1.9.8, RingoJS 0.11, & Rhino 1.7RC5.
 Automated [browser](https://saucelabs.com/u/lodash) & [CI](https://travis-ci.org/lodash/lodash/) test runs are available. Special thanks to [Sauce Labs](https://saucelabs.com/) for providing automated browser testing.

array/difference.js

@@ -1,16 +1,16 @@
 var baseDifference = require('../internal/baseDifference'),
     baseFlatten = require('../internal/baseFlatten'),
     isArguments = require('../lang/isArguments'),
-    isArray = require('../lang/isArray');
+    isArray = require('../lang/isArray'),
+    restParam = require('../function/restParam');
 
 /**
  * Creates an array excluding all values of the provided arrays using
  * `SameValueZero` for equality comparisons.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -23,18 +23,10 @@ var baseDifference = require('../internal/baseDifference'),
  * _.difference([1, 2, 3], [4, 2]);
  * // => [1, 3]
  */
-function difference() {
-  var args = arguments,
-      index = -1,
-      length = args.length;
-
-  while (++index < length) {
-    var value = args[index];
-    if (isArray(value) || isArguments(value)) {
-      break;
-    }
-  }
-  return baseDifference(value, baseFlatten(args, false, true, ++index));
-}
+var difference = restParam(function(array, values) {
+  return (isArray(array) || isArguments(array))
+    ? baseDifference(array, baseFlatten(values, false, true))
+    : [];
+});
 
 module.exports = difference;

array/dropRightWhile.js

@@ -1,10 +1,10 @@
 var baseCallback = require('../internal/baseCallback'),
-    baseSlice = require('../internal/baseSlice');
+    baseWhile = require('../internal/baseWhile');
 
 /**
  * Creates a slice of `array` excluding elements dropped from the end.
  * Elements are dropped until `predicate` returns falsey. The predicate is
- * bound to `thisArg` and invoked with three arguments; (value, index, array).
+ * bound to `thisArg` and invoked with three arguments: (value, index, array).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -51,13 +51,9 @@ var baseCallback = require('../internal/baseCallback'),
  * // => ['barney', 'fred', 'pebbles']
  */
 function dropRightWhile(array, predicate, thisArg) {
-  var length = array ? array.length : 0;
-  if (!length) {
-    return [];
-  }
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (length-- && predicate(array[length], length, array)) {}
-  return baseSlice(array, 0, length + 1);
+  return (array && array.length)
+    ? baseWhile(array, baseCallback(predicate, thisArg, 3), true, true)
+    : [];
 }
 
 module.exports = dropRightWhile;

array/dropWhile.js

@@ -1,10 +1,10 @@
 var baseCallback = require('../internal/baseCallback'),
-    baseSlice = require('../internal/baseSlice');
+    baseWhile = require('../internal/baseWhile');
 
 /**
  * Creates a slice of `array` excluding elements dropped from the beginning.
  * Elements are dropped until `predicate` returns falsey. The predicate is
- * bound to `thisArg` and invoked with three arguments; (value, index, array).
+ * bound to `thisArg` and invoked with three arguments: (value, index, array).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -51,14 +51,9 @@ var baseCallback = require('../internal/baseCallback'),
  * // => ['barney', 'fred', 'pebbles']
  */
 function dropWhile(array, predicate, thisArg) {
-  var length = array ? array.length : 0;
-  if (!length) {
-    return [];
-  }
-  var index = -1;
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (++index < length && predicate(array[index], index, array)) {}
-  return baseSlice(array, index);
+  return (array && array.length)
+    ? baseWhile(array, baseCallback(predicate, thisArg, 3), true)
+    : [];
 }
 
 module.exports = dropWhile;

array/fill.js

@@ -15,6 +15,19 @@ var baseFill = require('../internal/baseFill'),
  * @param {number} [start=0] The start position.
  * @param {number} [end=array.length] The end position.
  * @returns {Array} Returns `array`.
+ * @example
+ *
+ * var array = [1, 2, 3];
+ *
+ * _.fill(array, 'a');
+ * console.log(array);
+ * // => ['a', 'a', 'a']
+ *
+ * _.fill(Array(3), 2);
+ * // => [2, 2, 2]
+ *
+ * _.fill([4, 6, 8], '*', 1, 2);
+ * // => [4, '*', 8]
  */
 function fill(array, value, start, end) {
   var length = array ? array.length : 0;

array/findIndex.js

@@ -1,8 +1,8 @@
-var baseCallback = require('../internal/baseCallback');
+var createFindIndex = require('../internal/createFindIndex');
 
 /**
  * This method is like `_.find` except that it returns the index of the first
- * element `predicate` returns truthy for, instead of the element itself.
+ * element `predicate` returns truthy for instead of the element itself.
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -48,17 +48,6 @@ var baseCallback = require('../internal/baseCallback');
  * _.findIndex(users, 'active');
  * // => 2
  */
-function findIndex(array, predicate, thisArg) {
-  var index = -1,
-      length = array ? array.length : 0;
-
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (++index < length) {
-    if (predicate(array[index], index, array)) {
-      return index;
-    }
-  }
-  return -1;
-}
+var findIndex = createFindIndex();
 
 module.exports = findIndex;

array/findLastIndex.js

@@ -1,4 +1,4 @@
-var baseCallback = require('../internal/baseCallback');
+var createFindIndex = require('../internal/createFindIndex');
 
 /**
  * This method is like `_.findIndex` except that it iterates over elements
@@ -48,15 +48,6 @@ var baseCallback = require('../internal/baseCallback');
  * _.findLastIndex(users, 'active');
  * // => 0
  */
-function findLastIndex(array, predicate, thisArg) {
-  var length = array ? array.length : 0;
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (length--) {
-    if (predicate(array[length], length, array)) {
-      return length;
-    }
-  }
-  return -1;
-}
+var findLastIndex = createFindIndex(true);
 
 module.exports = findLastIndex;

array/flatten.js

@@ -15,18 +15,18 @@ var baseFlatten = require('../internal/baseFlatten'),
  * @example
  *
  * _.flatten([1, [2, 3, [4]]]);
- * // => [1, 2, 3, [4]];
+ * // => [1, 2, 3, [4]]
  *
  * // using `isDeep`
  * _.flatten([1, [2, 3, [4]]], true);
- * // => [1, 2, 3, 4];
+ * // => [1, 2, 3, 4]
  */
 function flatten(array, isDeep, guard) {
   var length = array ? array.length : 0;
   if (guard && isIterateeCall(array, isDeep, guard)) {
     isDeep = false;
   }
-  return length ? baseFlatten(array, isDeep, false, 0) : [];
+  return length ? baseFlatten(array, isDeep) : [];
 }
 
 module.exports = flatten;

array/flattenDeep.js

@@ -11,11 +11,11 @@ var baseFlatten = require('../internal/baseFlatten');
  * @example
  *
  * _.flattenDeep([1, [2, 3, [4]]]);
- * // => [1, 2, 3, 4];
+ * // => [1, 2, 3, 4]
  */
 function flattenDeep(array) {
   var length = array ? array.length : 0;
-  return length ? baseFlatten(array, true, false, 0) : [];
+  return length ? baseFlatten(array, true) : [];
 }
 
 module.exports = flattenDeep;

array/indexOf.js

@@ -10,10 +10,9 @@ var nativeMax = Math.max;
  * it is used as the offset from the end of `array`. If `array` is sorted
  * providing `true` for `fromIndex` performs a faster binary search.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _

array/intersection.js

@@ -8,10 +8,9 @@ var baseIndexOf = require('../internal/baseIndexOf'),
  * Creates an array of unique values in all provided arrays using `SameValueZero`
  * for equality comparisons.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -28,7 +27,8 @@ function intersection() {
       argsLength = arguments.length,
       caches = [],
       indexOf = baseIndexOf,
-      isCommon = true;
+      isCommon = true,
+      result = [];
 
   while (++argsIndex < argsLength) {
     var value = arguments[argsIndex];
@@ -38,10 +38,12 @@ function intersection() {
     }
   }
   argsLength = args.length;
+  if (argsLength < 2) {
+    return result;
+  }
   var array = args[0],
       index = -1,
       length = array ? array.length : 0,
-      result = [],
       seen = caches[0];
 
   outer:

array/pull.js

@@ -11,10 +11,10 @@ var splice = arrayProto.splice;
  * comparisons.
  *
  * **Notes:**
- *  - Unlike `_.without`, this method mutates `array`.
- *  - `SameValueZero` comparisons are like strict equality comparisons, e.g. `===`,
- *    except that `NaN` matches `NaN`. See the [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- *    for more details.
+ *  - Unlike `_.without`, this method mutates `array`
+ *  - [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ *    comparisons are like strict equality comparisons, e.g. `===`, except
+ *    that `NaN` matches `NaN`
  *
  * @static
  * @memberOf _

array/pullAt.js

@@ -1,5 +1,8 @@
-var baseFlatten = require('../internal/baseFlatten'),
-    basePullAt = require('../internal/basePullAt');
+var baseAt = require('../internal/baseAt'),
+    baseCompareAscending = require('../internal/baseCompareAscending'),
+    baseFlatten = require('../internal/baseFlatten'),
+    basePullAt = require('../internal/basePullAt'),
+    restParam = require('../function/restParam');
 
 /**
  * Removes elements from `array` corresponding to the given indexes and returns
@@ -26,8 +29,13 @@ var baseFlatten = require('../internal/baseFlatten'),
  * console.log(evens);
  * // => [10, 20]
  */
-function pullAt(array) {
-  return basePullAt(array || [], baseFlatten(arguments, false, false, 1));
-}
+var pullAt = restParam(function(array, indexes) {
+  array || (array = []);
+  indexes = baseFlatten(indexes);
+
+  var result = baseAt(array, indexes);
+  basePullAt(array, indexes.sort(baseCompareAscending));
+  return result;
+});
 
 module.exports = pullAt;

array/remove.js

@@ -1,15 +1,10 @@
-var baseCallback = require('../internal/baseCallback');
-
-/** Used for native method references. */
-var arrayProto = Array.prototype;
-
-/** Native method references. */
-var splice = arrayProto.splice;
+var baseCallback = require('../internal/baseCallback'),
+    basePullAt = require('../internal/basePullAt');
 
 /**
  * Removes all elements from `array` that `predicate` returns truthy for
  * and returns an array of the removed elements. The predicate is bound to
- * `thisArg` and invoked with three arguments; (value, index, array).
+ * `thisArg` and invoked with three arguments: (value, index, array).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -46,19 +41,23 @@ var splice = arrayProto.splice;
  * // => [2, 4]
  */
 function remove(array, predicate, thisArg) {
+  var result = [];
+  if (!(array && array.length)) {
+    return result;
+  }
   var index = -1,
-      length = array ? array.length : 0,
-      result = [];
+      indexes = [],
+      length = array.length;
 
   predicate = baseCallback(predicate, thisArg, 3);
   while (++index < length) {
     var value = array[index];
     if (predicate(value, index, array)) {
       result.push(value);
-      splice.call(array, index--, 1);
-      length--;
+      indexes.push(index);
     }
   }
+  basePullAt(array, indexes);
   return result;
 }
 

array/slice.js

@@ -4,7 +4,7 @@ var baseSlice = require('../internal/baseSlice'),
 /**
  * Creates a slice of `array` from `start` up to, but not including, `end`.
  *
- * **Note:** This function is used instead of `Array#slice` to support node
+ * **Note:** This method is used instead of `Array#slice` to support node
  * lists in IE < 9 and to ensure dense arrays are returned.
  *
  * @static

array/sortedIndex.js

@@ -1,6 +1,4 @@
-var baseCallback = require('../internal/baseCallback'),
-    binaryIndex = require('../internal/binaryIndex'),
-    binaryIndexBy = require('../internal/binaryIndexBy');
+var createSortedIndex = require('../internal/createSortedIndex');
 
 /**
  * Uses a binary search to determine the lowest index at which `value` should
@@ -9,14 +7,14 @@ var baseCallback = require('../internal/baseCallback'),
  * to compute their sort ranking. The iteratee is bound to `thisArg` and
  * invoked with one argument; (value).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *
@@ -50,10 +48,6 @@ var baseCallback = require('../internal/baseCallback'),
  * _.sortedIndex([{ 'x': 30 }, { 'x': 50 }], { 'x': 40 }, 'x');
  * // => 1
  */
-function sortedIndex(array, value, iteratee, thisArg) {
-  return iteratee == null
-    ? binaryIndex(array, value)
-    : binaryIndexBy(array, value, baseCallback(iteratee, thisArg, 1));
-}
+var sortedIndex = createSortedIndex();
 
 module.exports = sortedIndex;

array/sortedLastIndex.js

@@ -1,6 +1,4 @@
-var baseCallback = require('../internal/baseCallback'),
-    binaryIndex = require('../internal/binaryIndex'),
-    binaryIndexBy = require('../internal/binaryIndexBy');
+var createSortedIndex = require('../internal/createSortedIndex');
 
 /**
  * This method is like `_.sortedIndex` except that it returns the highest
@@ -22,10 +20,6 @@ var baseCallback = require('../internal/baseCallback'),
  * _.sortedLastIndex([4, 4, 5, 5], 5);
  * // => 4
  */
-function sortedLastIndex(array, value, iteratee, thisArg) {
-  return iteratee == null
-    ? binaryIndex(array, value, true)
-    : binaryIndexBy(array, value, baseCallback(iteratee, thisArg, 1), true);
-}
+var sortedLastIndex = createSortedIndex(true);
 
 module.exports = sortedLastIndex;

array/takeRightWhile.js

@@ -1,10 +1,10 @@
 var baseCallback = require('../internal/baseCallback'),
-    baseSlice = require('../internal/baseSlice');
+    baseWhile = require('../internal/baseWhile');
 
 /**
  * Creates a slice of `array` with elements taken from the end. Elements are
  * taken until `predicate` returns falsey. The predicate is bound to `thisArg`
- * and invoked with three arguments; (value, index, array).
+ * and invoked with three arguments: (value, index, array).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -51,13 +51,9 @@ var baseCallback = require('../internal/baseCallback'),
  * // => []
  */
 function takeRightWhile(array, predicate, thisArg) {
-  var length = array ? array.length : 0;
-  if (!length) {
-    return [];
-  }
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (length-- && predicate(array[length], length, array)) {}
-  return baseSlice(array, length + 1);
+  return (array && array.length)
+    ? baseWhile(array, baseCallback(predicate, thisArg, 3), false, true)
+    : [];
 }
 
 module.exports = takeRightWhile;

array/takeWhile.js

@@ -1,10 +1,10 @@
 var baseCallback = require('../internal/baseCallback'),
-    baseSlice = require('../internal/baseSlice');
+    baseWhile = require('../internal/baseWhile');
 
 /**
  * Creates a slice of `array` with elements taken from the beginning. Elements
  * are taken until `predicate` returns falsey. The predicate is bound to
- * `thisArg` and invoked with three arguments; (value, index, array).
+ * `thisArg` and invoked with three arguments: (value, index, array).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -51,14 +51,9 @@ var baseCallback = require('../internal/baseCallback'),
  * // => []
  */
 function takeWhile(array, predicate, thisArg) {
-  var length = array ? array.length : 0;
-  if (!length) {
-    return [];
-  }
-  var index = -1;
-  predicate = baseCallback(predicate, thisArg, 3);
-  while (++index < length && predicate(array[index], index, array)) {}
-  return baseSlice(array, 0, index);
+  return (array && array.length)
+    ? baseWhile(array, baseCallback(predicate, thisArg, 3))
+    : [];
 }
 
 module.exports = takeWhile;

array/union.js

@@ -1,14 +1,14 @@
 var baseFlatten = require('../internal/baseFlatten'),
-    baseUniq = require('../internal/baseUniq');
+    baseUniq = require('../internal/baseUniq'),
+    restParam = require('../function/restParam');
 
 /**
  * Creates an array of unique values, in order, of the provided arrays using
  * `SameValueZero` for equality comparisons.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -20,8 +20,8 @@ var baseFlatten = require('../internal/baseFlatten'),
  * _.union([1, 2], [4, 2], [2, 1]);
  * // => [1, 2, 4]
  */
-function union() {
-  return baseUniq(baseFlatten(arguments, false, true, 0));
-}
+var union = restParam(function(arrays) {
+  return baseUniq(baseFlatten(arrays, false, true));
+});
 
 module.exports = union;

array/uniq.js

@@ -4,28 +4,28 @@ var baseCallback = require('../internal/baseCallback'),
     sortedUniq = require('../internal/sortedUniq');
 
 /**
- * Creates a duplicate-value-free version of an array using `SameValueZero`
- * for equality comparisons. Providing `true` for `isSorted` performs a faster
- * search algorithm for sorted arrays. If an iteratee function is provided it
- * is invoked for each value in the array to generate the criterion by which
- * uniqueness is computed. The `iteratee` is bound to `thisArg` and invoked
- * with three arguments; (value, index, array).
+ * Creates a duplicate-free version of an array, using `SameValueZero` for
+ * equality comparisons, in which only the first occurence of each element
+ * is kept. Providing `true` for `isSorted` performs a faster search algorithm
+ * for sorted arrays. If an iteratee function is provided it is invoked for
+ * each element in the array to generate the criterion by which uniqueness
+ * is computed. The `iteratee` is bound to `thisArg` and invoked with three
+ * arguments: (value, index, array).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -38,8 +38,8 @@ var baseCallback = require('../internal/baseCallback'),
  * @returns {Array} Returns the new duplicate-value-free array.
  * @example
  *
- * _.uniq([1, 2, 1]);
- * // => [1, 2]
+ * _.uniq([2, 1, 2]);
+ * // => [2, 1]
  *
  * // using `isSorted`
  * _.uniq([1, 1, 2], true);

array/unzip.js

@@ -1,9 +1,7 @@
 var arrayMap = require('../internal/arrayMap'),
     arrayMax = require('../internal/arrayMax'),
-    baseProperty = require('../internal/baseProperty');
-
-/** Used to the length of n-tuples for `_.unzip`. */
-var getLength = baseProperty('length');
+    baseProperty = require('../internal/baseProperty'),
+    getLength = require('../internal/getLength');
 
 /**
  * This method is like `_.zip` except that it accepts an array of grouped

array/without.js

@@ -1,14 +1,15 @@
 var baseDifference = require('../internal/baseDifference'),
-    baseSlice = require('../internal/baseSlice');
+    isArguments = require('../lang/isArguments'),
+    isArray = require('../lang/isArray'),
+    restParam = require('../function/restParam');
 
 /**
  * Creates an array excluding all provided values using `SameValueZero` for
  * equality comparisons.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -21,8 +22,10 @@ var baseDifference = require('../internal/baseDifference'),
  * _.without([1, 2, 1, 3], 1, 2);
  * // => [3]
  */
-function without(array) {
-  return baseDifference(array, baseSlice(arguments, 1));
-}
+var without = restParam(function(array, values) {
+  return (isArray(array) || isArguments(array))
+    ? baseDifference(array, values)
+    : [];
+});
 
 module.exports = without;

array/xor.js

@@ -4,9 +4,8 @@ var baseDifference = require('../internal/baseDifference'),
     isArray = require('../lang/isArray');
 
 /**
- * Creates an array that is the symmetric difference of the provided arrays.
- * See [Wikipedia](https://en.wikipedia.org/wiki/Symmetric_difference) for
- * more details.
+ * Creates an array that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference)
+ * of the provided arrays.
  *
  * @static
  * @memberOf _

array/zip.js

@@ -1,4 +1,5 @@
-var unzip = require('./unzip');
+var restParam = require('../function/restParam'),
+    unzip = require('./unzip');
 
 /**
  * Creates an array of grouped elements, the first of which contains the first
@@ -15,14 +16,6 @@ var unzip = require('./unzip');
  * _.zip(['fred', 'barney'], [30, 40], [true, false]);
  * // => [['fred', 30, true], ['barney', 40, false]]
  */
-function zip() {
-  var length = arguments.length,
-      array = Array(length);
-
-  while (length--) {
-    array[length] = arguments[length];
-  }
-  return unzip(array);
-}
+var zip = restParam(unzip);
 
 module.exports = zip;

array/zipObject.js

@@ -1,9 +1,10 @@
 var isArray = require('../lang/isArray');
 
 /**
- * Creates an object composed from arrays of property names and values. Provide
- * either a single two dimensional array, e.g. `[[key1, value1], [key2, value2]]`
- * or two arrays, one of property names and one of corresponding values.
+ * The inverse of `_.pairs`; this method returns an object composed from arrays
+ * of property names and values. Provide either a single two dimensional array,
+ * e.g. `[[key1, value1], [key2, value2]]` or two arrays, one of property names
+ * and one of corresponding values.
  *
  * @static
  * @memberOf _
@@ -14,6 +15,9 @@ var isArray = require('../lang/isArray');
  * @returns {Object} Returns the new object.
  * @example
  *
+ * _.zipObject([['fred', 30], ['barney', 40]]);
+ * // => { 'fred': 30, 'barney': 40 }
+ *
  * _.zipObject(['fred', 'barney'], [30, 40]);
  * // => { 'fred': 30, 'barney': 40 }
  */

chain/lodash.js

@@ -50,8 +50,8 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * `filter`, `flatten`, `flattenDeep`, `flow`, `flowRight`, `forEach`,
  * `forEachRight`, `forIn`, `forInRight`, `forOwn`, `forOwnRight`, `functions`,
  * `groupBy`, `indexBy`, `initial`, `intersection`, `invert`, `invoke`, `keys`,
- * `keysIn`, `map`, `mapValues`, `matches`, `matchesProperty`, `memoize`, `merge`,
- * `mixin`, `negate`, `noop`, `omit`, `once`, `pairs`, `partial`, `partialRight`,
+ * `keysIn`, `map`, `mapValues`, `matches`, `matchesProperty`, `memoize`,
+ * `merge`, `mixin`, `negate`, `omit`, `once`, `pairs`, `partial`, `partialRight`,
  * `partition`, `pick`, `plant`, `pluck`, `property`, `propertyOf`, `pull`,
  * `pullAt`, `push`, `range`, `rearg`, `reject`, `remove`, `rest`, `reverse`,
  * `shuffle`, `slice`, `sort`, `sortBy`, `sortByAll`, `sortByOrder`, `splice`,
@@ -65,15 +65,15 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * `endsWith`, `escape`, `escapeRegExp`, `every`, `find`, `findIndex`, `findKey`,
  * `findLast`, `findLastIndex`, `findLastKey`, `findWhere`, `first`, `has`,
  * `identity`, `includes`, `indexOf`, `inRange`, `isArguments`, `isArray`,
- * `isBoolean`, `isDate`, `isElement`, `isEmpty`, `isEqual`, `isError`,
- * `isFinite`,`isFunction`, `isMatch`, `isNative`, `isNaN`, `isNull`, `isNumber`,
- * `isObject`, `isPlainObject`, `isRegExp`, `isString`, `isUndefined`,
- * `isTypedArray`, `join`, `kebabCase`, `last`, `lastIndexOf`, `max`, `min`,
- * `noConflict`, `now`, `pad`, `padLeft`, `padRight`, `parseInt`, `pop`,
- * `random`, `reduce`, `reduceRight`, `repeat`, `result`, `runInContext`,
- * `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedLastIndex`,
- * `startCase`, `startsWith`, `sum`, `template`, `trim`, `trimLeft`,
- * `trimRight`, `trunc`, `unescape`, `uniqueId`, `value`, and `words`
+ * `isBoolean`, `isDate`, `isElement`, `isEmpty`, `isEqual`, `isError`, `isFinite`
+ * `isFunction`, `isMatch`, `isNative`, `isNaN`, `isNull`, `isNumber`, `isObject`,
+ * `isPlainObject`, `isRegExp`, `isString`, `isUndefined`, `isTypedArray`,
+ * `join`, `kebabCase`, `last`, `lastIndexOf`, `max`, `min`, `noConflict`,
+ * `noop`, `now`, `pad`, `padLeft`, `padRight`, `parseInt`, `pop`, `random`,
+ * `reduce`, `reduceRight`, `repeat`, `result`, `runInContext`, `shift`, `size`,
+ * `snakeCase`, `some`, `sortedIndex`, `sortedLastIndex`, `startCase`, `startsWith`,
+ * `sum`, `template`, `trim`, `trimLeft`, `trimRight`, `trunc`, `unescape`,
+ * `uniqueId`, `value`, and `words`
  *
  * The wrapper method `sample` will return a wrapped value when `n` is provided,
  * otherwise an unwrapped value is returned.
@@ -88,8 +88,8 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * var wrapped = _([1, 2, 3]);
  *
  * // returns an unwrapped value
- * wrapped.reduce(function(sum, n) {
- *   return sum + n;
+ * wrapped.reduce(function(total, n) {
+ *   return total + n;
  * });
  * // => 6
  *

chain/thru.js

@@ -10,13 +10,14 @@
  * @returns {*} Returns the result of `interceptor`.
  * @example
  *
- * _([1, 2, 3])
- *  .last()
+ * _('  abc  ')
+ *  .chain()
+ *  .trim()
  *  .thru(function(value) {
  *    return [value];
  *  })
  *  .value();
- * // => [3]
+ * // => ['abc']
  */
 function thru(value, interceptor, thisArg) {
   return interceptor.call(thisArg, value);

collection/at.js

@@ -1,6 +1,8 @@
 var baseAt = require('../internal/baseAt'),
     baseFlatten = require('../internal/baseFlatten'),
+    getLength = require('../internal/getLength'),
     isLength = require('../internal/isLength'),
+    restParam = require('../function/restParam'),
     toIterable = require('../internal/toIterable');
 
 /**
@@ -20,15 +22,15 @@ var baseAt = require('../internal/baseAt'),
  * _.at(['a', 'b', 'c'], [0, 2]);
  * // => ['a', 'c']
  *
- * _.at(['fred', 'barney', 'pebbles'], 0, 2);
- * // => ['fred', 'pebbles']
+ * _.at(['barney', 'fred', 'pebbles'], 0, 2);
+ * // => ['barney', 'pebbles']
  */
-function at(collection) {
-  var length = collection ? collection.length : 0;
+var at = restParam(function(collection, props) {
+  var length = collection ? getLength(collection) : 0;
   if (isLength(length)) {
     collection = toIterable(collection);
   }
-  return baseAt(collection, baseFlatten(arguments, false, false, 1));
-}
+  return baseAt(collection, baseFlatten(props));
+});
 
 module.exports = at;

collection/countBy.js

@@ -10,17 +10,17 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * Creates an object composed of keys generated from the results of running
  * each element of `collection` through `iteratee`. The corresponding value
  * of each key is the number of times the key was returned by `iteratee`.
- * The `iteratee` is bound to `thisArg` and invoked with three arguments;
+ * The `iteratee` is bound to `thisArg` and invoked with three arguments:
  * (value, index|key, collection).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *

collection/every.js

@@ -1,11 +1,12 @@
 var arrayEvery = require('../internal/arrayEvery'),
     baseCallback = require('../internal/baseCallback'),
     baseEvery = require('../internal/baseEvery'),
-    isArray = require('../lang/isArray');
+    isArray = require('../lang/isArray'),
+    isIterateeCall = require('../internal/isIterateeCall');
 
 /**
  * Checks if `predicate` returns truthy for **all** elements of `collection`.
- * The predicate is bound to `thisArg` and invoked with three arguments;
+ * The predicate is bound to `thisArg` and invoked with three arguments:
  * (value, index|key, collection).
  *
  * If a property name is provided for `predicate` the created `_.property`
@@ -53,7 +54,10 @@ var arrayEvery = require('../internal/arrayEvery'),
  */
 function every(collection, predicate, thisArg) {
   var func = isArray(collection) ? arrayEvery : baseEvery;
-  if (typeof predicate != 'function' || typeof thisArg != 'undefined') {
+  if (thisArg && isIterateeCall(collection, predicate, thisArg)) {
+    predicate = null;
+  }
+  if (typeof predicate != 'function' || thisArg !== undefined) {
     predicate = baseCallback(predicate, thisArg, 3);
   }
   return func(collection, predicate);

collection/filter.js

@@ -6,7 +6,7 @@ var arrayFilter = require('../internal/arrayFilter'),
 /**
  * Iterates over elements of `collection`, returning an array of all elements
  * `predicate` returns truthy for. The predicate is bound to `thisArg` and
- * invoked with three arguments; (value, index|key, collection).
+ * invoked with three arguments: (value, index|key, collection).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.

collection/find.js

@@ -1,13 +1,10 @@
-var baseCallback = require('../internal/baseCallback'),
-    baseEach = require('../internal/baseEach'),
-    baseFind = require('../internal/baseFind'),
-    findIndex = require('../array/findIndex'),
-    isArray = require('../lang/isArray');
+var baseEach = require('../internal/baseEach'),
+    createFind = require('../internal/createFind');
 
 /**
  * Iterates over elements of `collection`, returning the first element
  * `predicate` returns truthy for. The predicate is bound to `thisArg` and
- * invoked with three arguments; (value, index|key, collection).
+ * invoked with three arguments: (value, index|key, collection).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -54,13 +51,6 @@ var baseCallback = require('../internal/baseCallback'),
  * _.result(_.find(users, 'active'), 'user');
  * // => 'barney'
  */
-function find(collection, predicate, thisArg) {
-  if (isArray(collection)) {
-    var index = findIndex(collection, predicate, thisArg);
-    return index > -1 ? collection[index] : undefined;
-  }
-  predicate = baseCallback(predicate, thisArg, 3);
-  return baseFind(collection, predicate, baseEach);
-}
+var find = createFind(baseEach);
 
 module.exports = find;

collection/findLast.js

@@ -1,6 +1,5 @@
-var baseCallback = require('../internal/baseCallback'),
-    baseEachRight = require('../internal/baseEachRight'),
-    baseFind = require('../internal/baseFind');
+var baseEachRight = require('../internal/baseEachRight'),
+    createFind = require('../internal/createFind');
 
 /**
  * This method is like `_.find` except that it iterates over elements of
@@ -21,9 +20,6 @@ var baseCallback = require('../internal/baseCallback'),
  * });
  * // => 3
  */
-function findLast(collection, predicate, thisArg) {
-  predicate = baseCallback(predicate, thisArg, 3);
-  return baseFind(collection, predicate, baseEachRight);
-}
+var findLast = createFind(baseEachRight, true);
 
 module.exports = findLast;

collection/forEach.js

@@ -1,15 +1,14 @@
 var arrayEach = require('../internal/arrayEach'),
     baseEach = require('../internal/baseEach'),
-    bindCallback = require('../internal/bindCallback'),
-    isArray = require('../lang/isArray');
+    createForEach = require('../internal/createForEach');
 
 /**
  * Iterates over elements of `collection` invoking `iteratee` for each element.
- * The `iteratee` is bound to `thisArg` and invoked with three arguments;
- * (value, index|key, collection). Iterator functions may exit iteration early
+ * The `iteratee` is bound to `thisArg` and invoked with three arguments:
+ * (value, index|key, collection). Iteratee functions may exit iteration early
  * by explicitly returning `false`.
  *
- * **Note:** As with other "Collections" methods, objects with a `length` property
+ * **Note:** As with other "Collections" methods, objects with a "length" property
  * are iterated like arrays. To avoid this behavior `_.forIn` or `_.forOwn`
  * may be used for object iteration.
  *
@@ -33,10 +32,6 @@ var arrayEach = require('../internal/arrayEach'),
  * });
  * // => logs each value-key pair and returns the object (iteration order is not guaranteed)
  */
-function forEach(collection, iteratee, thisArg) {
-  return (typeof iteratee == 'function' && typeof thisArg == 'undefined' && isArray(collection))
-    ? arrayEach(collection, iteratee)
-    : baseEach(collection, bindCallback(iteratee, thisArg, 3));
-}
+var forEach = createForEach(arrayEach, baseEach);
 
 module.exports = forEach;

collection/forEachRight.js

@@ -1,7 +1,6 @@
 var arrayEachRight = require('../internal/arrayEachRight'),
     baseEachRight = require('../internal/baseEachRight'),
-    bindCallback = require('../internal/bindCallback'),
-    isArray = require('../lang/isArray');
+    createForEach = require('../internal/createForEach');
 
 /**
  * This method is like `_.forEach` except that it iterates over elements of
@@ -19,13 +18,9 @@ var arrayEachRight = require('../internal/arrayEachRight'),
  *
  * _([1, 2]).forEachRight(function(n) {
  *   console.log(n);
- * }).join(',');
+ * }).value();
  * // => logs each value from right to left and returns the array
  */
-function forEachRight(collection, iteratee, thisArg) {
-  return (typeof iteratee == 'function' && typeof thisArg == 'undefined' && isArray(collection))
-    ? arrayEachRight(collection, iteratee)
-    : baseEachRight(collection, bindCallback(iteratee, thisArg, 3));
-}
+var forEachRight = createForEach(arrayEachRight, baseEachRight);
 
 module.exports = forEachRight;

collection/groupBy.js

@@ -10,17 +10,17 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * Creates an object composed of keys generated from the results of running
  * each element of `collection` through `iteratee`. The corresponding value
  * of each key is an array of the elements responsible for generating the key.
- * The `iteratee` is bound to `thisArg` and invoked with three arguments;
+ * The `iteratee` is bound to `thisArg` and invoked with three arguments:
  * (value, index|key, collection).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *

collection/includes.js

@@ -1,5 +1,7 @@
 var baseIndexOf = require('../internal/baseIndexOf'),
+    getLength = require('../internal/getLength'),
     isArray = require('../lang/isArray'),
+    isIterateeCall = require('../internal/isIterateeCall'),
     isLength = require('../internal/isLength'),
     isString = require('../lang/isString'),
     values = require('../object/values');
@@ -12,10 +14,9 @@ var nativeMax = Math.max;
  * comparisons. If `fromIndex` is negative, it is used as the offset from
  * the end of `collection`.
  *
- * **Note:** `SameValueZero` comparisons are like strict equality comparisons,
- * e.g. `===`, except that `NaN` matches `NaN`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
- * for more details.
+ * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+ * comparisons are like strict equality comparisons, e.g. `===`, except that
+ * `NaN` matches `NaN`.
  *
  * @static
  * @memberOf _
@@ -24,6 +25,7 @@ var nativeMax = Math.max;
  * @param {Array|Object|string} collection The collection to search.
  * @param {*} target The value to search for.
  * @param {number} [fromIndex=0] The index to search from.
+ * @param- {Object} [guard] Enables use as a callback for functions like `_.reduce`.
  * @returns {boolean} Returns `true` if a matching element is found, else `false`.
  * @example
  *
@@ -39,8 +41,8 @@ var nativeMax = Math.max;
  * _.includes('pebbles', 'eb');
  * // => true
  */
-function includes(collection, target, fromIndex) {
-  var length = collection ? collection.length : 0;
+function includes(collection, target, fromIndex, guard) {
+  var length = collection ? getLength(collection) : 0;
   if (!isLength(length)) {
     collection = values(collection);
     length = collection.length;
@@ -48,10 +50,10 @@ function includes(collection, target, fromIndex) {
   if (!length) {
     return false;
   }
-  if (typeof fromIndex == 'number') {
-    fromIndex = fromIndex < 0 ? nativeMax(length + fromIndex, 0) : (fromIndex || 0);
-  } else {
+  if (typeof fromIndex != 'number' || (guard && isIterateeCall(target, fromIndex, guard))) {
     fromIndex = 0;
+  } else {
+    fromIndex = fromIndex < 0 ? nativeMax(length + fromIndex, 0) : (fromIndex || 0);
   }
   return (typeof collection == 'string' || !isArray(collection) && isString(collection))
     ? (fromIndex < length && collection.indexOf(target, fromIndex) > -1)

collection/indexBy.js

@@ -4,17 +4,17 @@ var createAggregator = require('../internal/createAggregator');
  * Creates an object composed of keys generated from the results of running
  * each element of `collection` through `iteratee`. The corresponding value
  * of each key is the last element responsible for generating the key. The
- * iteratee function is bound to `thisArg` and invoked with three arguments;
+ * iteratee function is bound to `thisArg` and invoked with three arguments:
  * (value, index|key, collection).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *

collection/invoke.js

@@ -1,17 +1,21 @@
-var baseInvoke = require('../internal/baseInvoke'),
-    baseSlice = require('../internal/baseSlice');
+var baseEach = require('../internal/baseEach'),
+    getLength = require('../internal/getLength'),
+    invokePath = require('../internal/invokePath'),
+    isKey = require('../internal/isKey'),
+    isLength = require('../internal/isLength'),
+    restParam = require('../function/restParam');
 
 /**
- * Invokes the method named by `methodName` on each element in `collection`,
- * returning an array of the results of each invoked method. Any additional
- * arguments are provided to each invoked method. If `methodName` is a function
- * it is invoked for, and `this` bound to, each element in `collection`.
+ * Invokes the method at `path` on each element in `collection`, returning
+ * an array of the results of each invoked method. Any additional arguments
+ * are provided to each invoked method. If `methodName` is a function it is
+ * invoked for, and `this` bound to, each element in `collection`.
  *
  * @static
  * @memberOf _
  * @category Collection
  * @param {Array|Object|string} collection The collection to iterate over.
- * @param {Function|string} methodName The name of the method to invoke or
+ * @param {Array|Function|string} path The path of the method to invoke or
  *  the function invoked per iteration.
  * @param {...*} [args] The arguments to invoke the method with.
  * @returns {Array} Returns the array of results.
@@ -23,8 +27,18 @@ var baseInvoke = require('../internal/baseInvoke'),
  * _.invoke([123, 456], String.prototype.split, '');
  * // => [['1', '2', '3'], ['4', '5', '6']]
  */
-function invoke(collection, methodName) {
-  return baseInvoke(collection, methodName, baseSlice(arguments, 2));
-}
+var invoke = restParam(function(collection, path, args) {
+  var index = -1,
+      isFunc = typeof path == 'function',
+      isProp = isKey(path),
+      length = getLength(collection),
+      result = isLength(length) ? Array(length) : [];
+
+  baseEach(collection, function(value) {
+    var func = isFunc ? path : (isProp && value != null && value[path]);
+    result[++index] = func ? func.apply(value, args) : invokePath(value, path, args);
+  });
+  return result;
+});
 
 module.exports = invoke;

collection/map.js

@@ -6,16 +6,16 @@ var arrayMap = require('../internal/arrayMap'),
 /**
  * Creates an array of values by running each element in `collection` through
  * `iteratee`. The `iteratee` is bound to `thisArg` and invoked with three
- * arguments; (value, index|key, collection).
+ * arguments: (value, index|key, collection).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *
@@ -24,9 +24,9 @@ var arrayMap = require('../internal/arrayMap'),
  *
  * The guarded methods are:
  * `ary`, `callback`, `chunk`, `clone`, `create`, `curry`, `curryRight`, `drop`,
- * `dropRight`, `fill`, `flatten`, `invert`, `max`, `min`, `parseInt`, `slice`,
- * `sortBy`, `take`, `takeRight`, `template`, `trim`, `trimLeft`, `trimRight`,
- * `trunc`, `random`, `range`, `sample`, `uniq`, and `words`
+ * `dropRight`, `every`, `fill`, `flatten`, `invert`, `max`, `min`, `parseInt`,
+ * `slice`, `sortBy`, `take`, `takeRight`, `template`, `trim`, `trimLeft`,
+ * `trimRight`, `trunc`, `random`, `range`, `sample`, `some`, `uniq`, and `words`
  *
  * @static
  * @memberOf _
@@ -35,7 +35,6 @@ var arrayMap = require('../internal/arrayMap'),
  * @param {Array|Object|string} collection The collection to iterate over.
  * @param {Function|Object|string} [iteratee=_.identity] The function invoked
  *  per iteration.
- *  create a `_.property` or `_.matches` style callback respectively.
  * @param {*} [thisArg] The `this` binding of `iteratee`.
  * @returns {Array} Returns the new mapped array.
  * @example

collection/partition.js

@@ -4,7 +4,7 @@ var createAggregator = require('../internal/createAggregator');
  * Creates an array of elements split into two groups, the first of which
  * contains elements `predicate` returns truthy for, while the second of which
  * contains elements `predicate` returns falsey for. The predicate is bound
- * to `thisArg` and invoked with three arguments; (value, index|key, collection).
+ * to `thisArg` and invoked with three arguments: (value, index|key, collection).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.

collection/pluck.js

@@ -1,14 +1,14 @@
-var baseProperty = require('../internal/baseProperty'),
-    map = require('./map');
+var map = require('./map'),
+    property = require('../utility/property');
 
 /**
- * Gets the value of `key` from all elements in `collection`.
+ * Gets the property value of `path` from all elements in `collection`.
  *
  * @static
  * @memberOf _
  * @category Collection
  * @param {Array|Object|string} collection The collection to iterate over.
- * @param {string} key The key of the property to pluck.
+ * @param {Array|string} path The path of the property to pluck.
  * @returns {Array} Returns the property values.
  * @example
  *
@@ -24,8 +24,8 @@ var baseProperty = require('../internal/baseProperty'),
  * _.pluck(userIndex, 'age');
  * // => [36, 40] (iteration order is not guaranteed)
  */
-function pluck(collection, key) {
-  return map(collection, baseProperty(key));
+function pluck(collection, path) {
+  return map(collection, property(path));
 }
 
 module.exports = pluck;

collection/reduce.js

@@ -1,22 +1,20 @@
 var arrayReduce = require('../internal/arrayReduce'),
-    baseCallback = require('../internal/baseCallback'),
     baseEach = require('../internal/baseEach'),
-    baseReduce = require('../internal/baseReduce'),
-    isArray = require('../lang/isArray');
+    createReduce = require('../internal/createReduce');
 
 /**
  * Reduces `collection` to a value which is the accumulated result of running
  * each element in `collection` through `iteratee`, where each successive
  * invocation is supplied the return value of the previous. If `accumulator`
  * is not provided the first element of `collection` is used as the initial
- * value. The `iteratee` is bound to `thisArg`and invoked with four arguments;
+ * value. The `iteratee` is bound to `thisArg` and invoked with four arguments:
  * (accumulator, value, index|key, collection).
  *
  * Many lodash methods are guarded to work as interatees for methods like
  * `_.reduce`, `_.reduceRight`, and `_.transform`.
  *
  * The guarded methods are:
- * `assign`, `defaults`, `merge`, and `sortAllBy`
+ * `assign`, `defaults`, `includes`, `merge`, `sortByAll`, and `sortByOrder`
  *
  * @static
  * @memberOf _
@@ -29,8 +27,8 @@ var arrayReduce = require('../internal/arrayReduce'),
  * @returns {*} Returns the accumulated value.
  * @example
  *
- * _.reduce([1, 2], function(sum, n) {
- *   return sum + n;
+ * _.reduce([1, 2], function(total, n) {
+ *   return total + n;
  * });
  * // => 3
  *
@@ -40,9 +38,6 @@ var arrayReduce = require('../internal/arrayReduce'),
  * }, {});
  * // => { 'a': 3, 'b': 6 } (iteration order is not guaranteed)
  */
-function reduce(collection, iteratee, accumulator, thisArg) {
-  var func = isArray(collection) ? arrayReduce : baseReduce;
-  return func(collection, baseCallback(iteratee, thisArg, 4), accumulator, arguments.length < 3, baseEach);
-}
+var reduce = createReduce(arrayReduce, baseEach);
 
 module.exports = reduce;

collection/reduceRight.js

@@ -1,8 +1,6 @@
 var arrayReduceRight = require('../internal/arrayReduceRight'),
-    baseCallback = require('../internal/baseCallback'),
     baseEachRight = require('../internal/baseEachRight'),
-    baseReduce = require('../internal/baseReduce'),
-    isArray = require('../lang/isArray');
+    createReduce = require('../internal/createReduce');
 
 /**
  * This method is like `_.reduce` except that it iterates over elements of
@@ -26,9 +24,6 @@ var arrayReduceRight = require('../internal/arrayReduceRight'),
  * }, []);
  * // => [4, 5, 2, 3, 0, 1]
  */
-function reduceRight(collection, iteratee, accumulator, thisArg) {
-  var func = isArray(collection) ? arrayReduceRight : baseReduce;
-  return func(collection, baseCallback(iteratee, thisArg, 4), accumulator, arguments.length < 3, baseEachRight);
-}
+var reduceRight =  createReduce(arrayReduceRight, baseEachRight);
 
 module.exports = reduceRight;

collection/shuffle.js

@@ -2,9 +2,8 @@ var baseRandom = require('../internal/baseRandom'),
     toIterable = require('../internal/toIterable');
 
 /**
- * Creates an array of shuffled values, using a version of the Fisher-Yates
- * shuffle. See [Wikipedia](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle)
- * for more details.
+ * Creates an array of shuffled values, using a version of the
+ * [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
  *
  * @static
  * @memberOf _

collection/size.js

@@ -1,4 +1,5 @@
-var isLength = require('../internal/isLength'),
+var getLength = require('../internal/getLength'),
+    isLength = require('../internal/isLength'),
     keys = require('../object/keys');
 
 /**
@@ -22,7 +23,7 @@ var isLength = require('../internal/isLength'),
  * // => 7
  */
 function size(collection) {
-  var length = collection ? collection.length : 0;
+  var length = collection ? getLength(collection) : 0;
   return isLength(length) ? length : keys(collection).length;
 }
 

collection/some.js

@@ -1,13 +1,14 @@
 var arraySome = require('../internal/arraySome'),
     baseCallback = require('../internal/baseCallback'),
     baseSome = require('../internal/baseSome'),
-    isArray = require('../lang/isArray');
+    isArray = require('../lang/isArray'),
+    isIterateeCall = require('../internal/isIterateeCall');
 
 /**
  * Checks if `predicate` returns truthy for **any** element of `collection`.
  * The function returns as soon as it finds a passing value and does not iterate
  * over the entire collection. The predicate is bound to `thisArg` and invoked
- * with three arguments; (value, index|key, collection).
+ * with three arguments: (value, index|key, collection).
  *
  * If a property name is provided for `predicate` the created `_.property`
  * style callback returns the property value of the given element.
@@ -54,7 +55,10 @@ var arraySome = require('../internal/arraySome'),
  */
 function some(collection, predicate, thisArg) {
   var func = isArray(collection) ? arraySome : baseSome;
-  if (typeof predicate != 'function' || typeof thisArg != 'undefined') {
+  if (thisArg && isIterateeCall(collection, predicate, thisArg)) {
+    predicate = null;
+  }
+  if (typeof predicate != 'function' || thisArg !== undefined) {
     predicate = baseCallback(predicate, thisArg, 3);
   }
   return func(collection, predicate);

collection/sortBy.js

@@ -1,25 +1,24 @@
 var baseCallback = require('../internal/baseCallback'),
-    baseEach = require('../internal/baseEach'),
+    baseMap = require('../internal/baseMap'),
     baseSortBy = require('../internal/baseSortBy'),
     compareAscending = require('../internal/compareAscending'),
-    isIterateeCall = require('../internal/isIterateeCall'),
-    isLength = require('../internal/isLength');
+    isIterateeCall = require('../internal/isIterateeCall');
 
 /**
  * Creates an array of elements, sorted in ascending order by the results of
  * running each element in a collection through `iteratee`. This method performs
  * a stable sort, that is, it preserves the original sort order of equal elements.
- * The `iteratee` is bound to `thisArg` and invoked with three arguments;
+ * The `iteratee` is bound to `thisArg` and invoked with three arguments:
  * (value, index|key, collection).
  *
- * If a property name is provided for `predicate` the created `_.property`
+ * If a property name is provided for `iteratee` the created `_.property`
  * style callback returns the property value of the given element.
  *
  * If a value is also provided for `thisArg` the created `_.matchesProperty`
  * style callback returns `true` for elements that have a matching property
  * value, else `false`.
  *
- * If an object is provided for `predicate` the created `_.matches` style
+ * If an object is provided for `iteratee` the created `_.matches` style
  * callback returns `true` for elements that have the properties of the given
  * object, else `false`.
  *
@@ -27,9 +26,8 @@ var baseCallback = require('../internal/baseCallback'),
  * @memberOf _
  * @category Collection
  * @param {Array|Object|string} collection The collection to iterate over.
- * @param {Array|Function|Object|string} [iteratee=_.identity] The function
- *  invoked per iteration. If a property name or an object is provided it is
- *  used to create a `_.property` or `_.matches` style callback respectively.
+ * @param {Function|Object|string} [iteratee=_.identity] The function invoked
+ *  per iteration.
  * @param {*} [thisArg] The `this` binding of `iteratee`.
  * @returns {Array} Returns the new sorted array.
  * @example
@@ -58,16 +56,14 @@ function sortBy(collection, iteratee, thisArg) {
   if (collection == null) {
     return [];
   }
-  var index = -1,
-      length = collection.length,
-      result = isLength(length) ? Array(length) : [];
-
   if (thisArg && isIterateeCall(collection, iteratee, thisArg)) {
     iteratee = null;
   }
+  var index = -1;
   iteratee = baseCallback(iteratee, thisArg, 3);
-  baseEach(collection, function(value, key, collection) {
-    result[++index] = { 'criteria': iteratee(value, key, collection), 'index': index, 'value': value };
+
+  var result = baseMap(collection, function(value, key, collection) {
+    return { 'criteria': iteratee(value, key, collection), 'index': ++index, 'value': value };
   });
   return baseSortBy(result, compareAscending);
 }

collection/sortByAll.js

@@ -1,41 +1,52 @@
 var baseFlatten = require('../internal/baseFlatten'),
     baseSortByOrder = require('../internal/baseSortByOrder'),
-    isIterateeCall = require('../internal/isIterateeCall');
+    isIterateeCall = require('../internal/isIterateeCall'),
+    restParam = require('../function/restParam');
 
 /**
- * This method is like `_.sortBy` except that it sorts by property names
- * instead of an iteratee function.
+ * This method is like `_.sortBy` except that it can sort by multiple iteratees
+ * or property names.
+ *
+ * If a property name is provided for an iteratee the created `_.property`
+ * style callback returns the property value of the given element.
+ *
+ * If an object is provided for an iteratee the created `_.matches` style
+ * callback returns `true` for elements that have the properties of the given
+ * object, else `false`.
  *
  * @static
  * @memberOf _
  * @category Collection
  * @param {Array|Object|string} collection The collection to iterate over.
- * @param {...(string|string[])} props The property names to sort by,
- *  specified as individual property names or arrays of property names.
+ * @param {...(Function|Function[]|Object|Object[]|string|string[])} iteratees
+ *  The iteratees to sort by, specified as individual values or arrays of values.
  * @returns {Array} Returns the new sorted array.
  * @example
  *
  * var users = [
+ *   { 'user': 'fred',   'age': 48 },
  *   { 'user': 'barney', 'age': 36 },
- *   { 'user': 'fred',   'age': 40 },
- *   { 'user': 'barney', 'age': 26 },
- *   { 'user': 'fred',   'age': 30 }
+ *   { 'user': 'fred',   'age': 42 },
+ *   { 'user': 'barney', 'age': 34 }
  * ];
  *
  * _.map(_.sortByAll(users, ['user', 'age']), _.values);
- * // => [['barney', 26], ['barney', 36], ['fred', 30], ['fred', 40]]
+ * // => [['barney', 34], ['barney', 36], ['fred', 42], ['fred', 48]]
+ *
+ * _.map(_.sortByAll(users, 'user', function(chr) {
+ *   return Math.floor(chr.age / 10);
+ * }), _.values);
+ * // => [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
  */
-function sortByAll(collection) {
+var sortByAll = restParam(function(collection, iteratees) {
   if (collection == null) {
     return [];
   }
-  var args = arguments,
-      guard = args[3];
-
-  if (guard && isIterateeCall(args[1], args[2], guard)) {
-    args = [collection, args[1]];
+  var guard = iteratees[2];
+  if (guard && isIterateeCall(iteratees[0], iteratees[1], guard)) {
+    iteratees.length = 1;
   }
-  return baseSortByOrder(collection, baseFlatten(args, false, false, 1), []);
-}
+  return baseSortByOrder(collection, baseFlatten(iteratees), []);
+});
 
 module.exports = sortByAll;

collection/sortByOrder.js

@@ -4,45 +4,52 @@ var baseSortByOrder = require('../internal/baseSortByOrder'),
 
 /**
  * This method is like `_.sortByAll` except that it allows specifying the
- * sort orders of the property names to sort by. A truthy value in `orders`
- * will sort the corresponding property name in ascending order while a
- * falsey value will sort it in descending order.
+ * sort orders of the iteratees to sort by. A truthy value in `orders` will
+ * sort the corresponding property name in ascending order while a falsey
+ * value will sort it in descending order.
+ *
+ * If a property name is provided for an iteratee the created `_.property`
+ * style callback returns the property value of the given element.
+ *
+ * If an object is provided for an iteratee the created `_.matches` style
+ * callback returns `true` for elements that have the properties of the given
+ * object, else `false`.
  *
  * @static
  * @memberOf _
  * @category Collection
  * @param {Array|Object|string} collection The collection to iterate over.
- * @param {string[]} props The property names to sort by.
- * @param {boolean[]} orders The sort orders of `props`.
+ * @param {Function[]|Object[]|string[]} iteratees The iteratees to sort by.
+ * @param {boolean[]} orders The sort orders of `iteratees`.
  * @param- {Object} [guard] Enables use as a callback for functions like `_.reduce`.
  * @returns {Array} Returns the new sorted array.
  * @example
  *
  * var users = [
- *   { 'user': 'barney', 'age': 26 },
- *   { 'user': 'fred',   'age': 40 },
- *   { 'user': 'barney', 'age': 36 },
- *   { 'user': 'fred',   'age': 30 }
+ *   { 'user': 'fred',   'age': 48 },
+ *   { 'user': 'barney', 'age': 34 },
+ *   { 'user': 'fred',   'age': 42 },
+ *   { 'user': 'barney', 'age': 36 }
  * ];
  *
  * // sort by `user` in ascending order and by `age` in descending order
  * _.map(_.sortByOrder(users, ['user', 'age'], [true, false]), _.values);
- * // => [['barney', 36], ['barney', 26], ['fred', 40], ['fred', 30]]
+ * // => [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
  */
-function sortByOrder(collection, props, orders, guard) {
+function sortByOrder(collection, iteratees, orders, guard) {
   if (collection == null) {
     return [];
   }
-  if (guard && isIterateeCall(props, orders, guard)) {
+  if (guard && isIterateeCall(iteratees, orders, guard)) {
     orders = null;
   }
-  if (!isArray(props)) {
-    props = props == null ? [] : [props];
+  if (!isArray(iteratees)) {
+    iteratees = iteratees == null ? [] : [iteratees];
   }
   if (!isArray(orders)) {
     orders = orders == null ? [] : [orders];
   }
-  return baseSortByOrder(collection, props, orders);
+  return baseSortByOrder(collection, iteratees, orders);
 }
 
 module.exports = sortByOrder;

function.js

@@ -20,6 +20,7 @@ module.exports = {
   'partial': require('./function/partial'),
   'partialRight': require('./function/partialRight'),
   'rearg': require('./function/rearg'),
+  'restParam': require('./function/restParam'),
   'spread': require('./function/spread'),
   'throttle': require('./function/throttle'),
   'wrap': require('./function/wrap')

function/ary.js

@@ -2,7 +2,7 @@ var createWrapper = require('../internal/createWrapper'),
     isIterateeCall = require('../internal/isIterateeCall');
 
 /** Used to compose bitmasks for wrapper metadata. */
-var ARY_FLAG = 256;
+var ARY_FLAG = 128;
 
 /* Native method references for those with the same name as other `lodash` methods. */
 var nativeMax = Math.max;

function/before.js

@@ -31,7 +31,8 @@ function before(n, func) {
   return function() {
     if (--n > 0) {
       result = func.apply(this, arguments);
-    } else {
+    }
+    if (n <= 1) {
       func = null;
     }
     return result;

function/bind.js

@@ -1,6 +1,6 @@
-var baseSlice = require('../internal/baseSlice'),
-    createWrapper = require('../internal/createWrapper'),
-    replaceHolders = require('../internal/replaceHolders');
+var createWrapper = require('../internal/createWrapper'),
+    replaceHolders = require('../internal/replaceHolders'),
+    restParam = require('./restParam');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var BIND_FLAG = 1,
@@ -14,7 +14,7 @@ var BIND_FLAG = 1,
  * The `_.bind.placeholder` value, which defaults to `_` in monolithic builds,
  * may be used as a placeholder for partially applied arguments.
  *
- * **Note:** Unlike native `Function#bind` this method does not set the `length`
+ * **Note:** Unlike native `Function#bind` this method does not set the "length"
  * property of bound functions.
  *
  * @static
@@ -22,7 +22,7 @@ var BIND_FLAG = 1,
  * @category Function
  * @param {Function} func The function to bind.
  * @param {*} thisArg The `this` binding of `func`.
- * @param {...*} [args] The arguments to be partially applied.
+ * @param {...*} [partials] The arguments to be partially applied.
  * @returns {Function} Returns the new bound function.
  * @example
  *
@@ -41,16 +41,14 @@ var BIND_FLAG = 1,
  * bound('hi');
  * // => 'hi fred!'
  */
-function bind(func, thisArg) {
+var bind = restParam(function(func, thisArg, partials) {
   var bitmask = BIND_FLAG;
-  if (arguments.length > 2) {
-    var partials = baseSlice(arguments, 2),
-        holders = replaceHolders(partials, bind.placeholder);
-
+  if (partials.length) {
+    var holders = replaceHolders(partials, bind.placeholder);
     bitmask |= PARTIAL_FLAG;
   }
   return createWrapper(func, bitmask, thisArg, partials, holders);
-}
+});
 
 // Assign default placeholders.
 bind.placeholder = {};

function/bindAll.js

@@ -1,6 +1,10 @@
-var baseBindAll = require('../internal/baseBindAll'),
-    baseFlatten = require('../internal/baseFlatten'),
-    functions = require('../object/functions');
+var baseFlatten = require('../internal/baseFlatten'),
+    createWrapper = require('../internal/createWrapper'),
+    functions = require('../object/functions'),
+    restParam = require('./restParam');
+
+/** Used to compose bitmasks for wrapper metadata. */
+var BIND_FLAG = 1;
 
 /**
  * Binds methods of an object to the object itself, overwriting the existing
@@ -8,7 +12,7 @@ var baseBindAll = require('../internal/baseBindAll'),
  * of method names. If no method names are provided all enumerable function
  * properties, own and inherited, of `object` are bound.
  *
- * **Note:** This method does not set the `length` property of bound functions.
+ * **Note:** This method does not set the "length" property of bound functions.
  *
  * @static
  * @memberOf _
@@ -30,12 +34,17 @@ var baseBindAll = require('../internal/baseBindAll'),
  * jQuery('#docs').on('click', view.onClick);
  * // => logs 'clicked docs' when the element is clicked
  */
-function bindAll(object) {
-  return baseBindAll(object,
-    arguments.length > 1
-      ? baseFlatten(arguments, false, false, 1)
-      : functions(object)
-  );
-}
+var bindAll = restParam(function(object, methodNames) {
+  methodNames = methodNames.length ? baseFlatten(methodNames) : functions(object);
+
+  var index = -1,
+      length = methodNames.length;
+
+  while (++index < length) {
+    var key = methodNames[index];
+    object[key] = createWrapper(object[key], BIND_FLAG, object);
+  }
+  return object;
+});
 
 module.exports = bindAll;

function/bindKey.js

@@ -1,6 +1,6 @@
-var baseSlice = require('../internal/baseSlice'),
-    createWrapper = require('../internal/createWrapper'),
-    replaceHolders = require('../internal/replaceHolders');
+var createWrapper = require('../internal/createWrapper'),
+    replaceHolders = require('../internal/replaceHolders'),
+    restParam = require('./restParam');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var BIND_FLAG = 1,
@@ -13,7 +13,7 @@ var BIND_FLAG = 1,
  *
  * This method differs from `_.bind` by allowing bound functions to reference
  * methods that may be redefined or don't yet exist.
- * See [Peter Michaux's article](http://michaux.ca/articles/lazy-function-definition-pattern)
+ * See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern)
  * for more details.
  *
  * The `_.bindKey.placeholder` value, which defaults to `_` in monolithic
@@ -24,7 +24,7 @@ var BIND_FLAG = 1,
  * @category Function
  * @param {Object} object The object the method belongs to.
  * @param {string} key The key of the method.
- * @param {...*} [args] The arguments to be partially applied.
+ * @param {...*} [partials] The arguments to be partially applied.
  * @returns {Function} Returns the new bound function.
  * @example
  *
@@ -51,16 +51,14 @@ var BIND_FLAG = 1,
  * bound('hi');
  * // => 'hiya fred!'
  */
-function bindKey(object, key) {
+var bindKey = restParam(function(object, key, partials) {
   var bitmask = BIND_FLAG | BIND_KEY_FLAG;
-  if (arguments.length > 2) {
-    var partials = baseSlice(arguments, 2),
-        holders = replaceHolders(partials, bindKey.placeholder);
-
+  if (partials.length) {
+    var holders = replaceHolders(partials, bindKey.placeholder);
     bitmask |= PARTIAL_FLAG;
   }
   return createWrapper(key, bitmask, object, partials, holders);
-}
+});
 
 // Assign default placeholders.
 bindKey.placeholder = {};

function/curry.js

@@ -1,5 +1,4 @@
-var createWrapper = require('../internal/createWrapper'),
-    isIterateeCall = require('../internal/isIterateeCall');
+var createCurry = require('../internal/createCurry');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var CURRY_FLAG = 8;
@@ -14,7 +13,7 @@ var CURRY_FLAG = 8;
  * The `_.curry.placeholder` value, which defaults to `_` in monolithic builds,
  * may be used as a placeholder for provided arguments.
  *
- * **Note:** This method does not set the `length` property of curried functions.
+ * **Note:** This method does not set the "length" property of curried functions.
  *
  * @static
  * @memberOf _
@@ -44,14 +43,7 @@ var CURRY_FLAG = 8;
  * curried(1)(_, 3)(2);
  * // => [1, 2, 3]
  */
-function curry(func, arity, guard) {
-  if (guard && isIterateeCall(func, arity, guard)) {
-    arity = null;
-  }
-  var result = createWrapper(func, CURRY_FLAG, null, null, null, null, null, arity);
-  result.placeholder = curry.placeholder;
-  return result;
-}
+var curry = createCurry(CURRY_FLAG);
 
 // Assign default placeholders.
 curry.placeholder = {};

function/curryRight.js

@@ -1,5 +1,4 @@
-var createWrapper = require('../internal/createWrapper'),
-    isIterateeCall = require('../internal/isIterateeCall');
+var createCurry = require('../internal/createCurry');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var CURRY_RIGHT_FLAG = 16;
@@ -11,7 +10,7 @@ var CURRY_RIGHT_FLAG = 16;
  * The `_.curryRight.placeholder` value, which defaults to `_` in monolithic
  * builds, may be used as a placeholder for provided arguments.
  *
- * **Note:** This method does not set the `length` property of curried functions.
+ * **Note:** This method does not set the "length" property of curried functions.
  *
  * @static
  * @memberOf _
@@ -41,14 +40,7 @@ var CURRY_RIGHT_FLAG = 16;
  * curried(3)(1, _)(2);
  * // => [1, 2, 3]
  */
-function curryRight(func, arity, guard) {
-  if (guard && isIterateeCall(func, arity, guard)) {
-    arity = null;
-  }
-  var result = createWrapper(func, CURRY_RIGHT_FLAG, null, null, null, null, null, arity);
-  result.placeholder = curryRight.placeholder;
-  return result;
-}
+var curryRight = createCurry(CURRY_RIGHT_FLAG);
 
 // Assign default placeholders.
 curryRight.placeholder = {};

function/defer.js

@@ -1,4 +1,5 @@
-var baseDelay = require('../internal/baseDelay');
+var baseDelay = require('../internal/baseDelay'),
+    restParam = require('./restParam');
 
 /**
  * Defers invoking the `func` until the current call stack has cleared. Any
@@ -17,8 +18,8 @@ var baseDelay = require('../internal/baseDelay');
  * }, 'deferred');
  * // logs 'deferred' after one or more milliseconds
  */
-function defer(func) {
-  return baseDelay(func, 1, arguments, 1);
-}
+var defer = restParam(function(func, args) {
+  return baseDelay(func, 1, args);
+});
 
 module.exports = defer;

function/delay.js

@@ -1,4 +1,5 @@
-var baseDelay = require('../internal/baseDelay');
+var baseDelay = require('../internal/baseDelay'),
+    restParam = require('./restParam');
 
 /**
  * Invokes `func` after `wait` milliseconds. Any additional arguments are
@@ -18,8 +19,8 @@ var baseDelay = require('../internal/baseDelay');
  * }, 1000, 'later');
  * // => logs 'later' after one second
  */
-function delay(func, wait) {
-  return baseDelay(func, wait, arguments, 2);
-}
+var delay = restParam(function(func, wait, args) {
+  return baseDelay(func, wait, args);
+});
 
 module.exports = delay;

function/flow.js

@@ -1,4 +1,4 @@
-var createComposer = require('../internal/createComposer');
+var createFlow = require('../internal/createFlow');
 
 /**
  * Creates a function that returns the result of invoking the provided
@@ -20,6 +20,6 @@ var createComposer = require('../internal/createComposer');
  * addSquare(1, 2);
  * // => 9
  */
-var flow = createComposer();
+var flow = createFlow();
 
 module.exports = flow;

function/flowRight.js

@@ -1,4 +1,4 @@
-var createComposer = require('../internal/createComposer');
+var createFlow = require('../internal/createFlow');
 
 /**
  * This method is like `_.flow` except that it creates a function that
@@ -20,6 +20,6 @@ var createComposer = require('../internal/createComposer');
  * addSquare(1, 2);
  * // => 9
  */
-var flowRight = createComposer(true);
+var flowRight = createFlow(true);
 
 module.exports = flowRight;

function/memoize.js

@@ -13,10 +13,8 @@ var FUNC_ERROR_TEXT = 'Expected a function';
  *
  * **Note:** The cache is exposed as the `cache` property on the memoized
  * function. Its creation may be customized by replacing the `_.memoize.Cache`
- * constructor with one whose instances implement the ES `Map` method interface
- * of `get`, `has`, and `set`. See the
- * [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-properties-of-the-map-prototype-object)
- * for more details.
+ * constructor with one whose instances implement the [`Map`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-properties-of-the-map-prototype-object)
+ * method interface of `get`, `has`, and `set`.
  *
  * @static
  * @memberOf _

function/once.js

@@ -3,7 +3,7 @@ var before = require('./before');
 /**
  * Creates a function that is restricted to invoking `func` once. Repeat calls
  * to the function return the value of the first call. The `func` is invoked
- * with the `this` binding of the created function.
+ * with the `this` binding and arguments of the created function.
  *
  * @static
  * @memberOf _
@@ -18,7 +18,7 @@ var before = require('./before');
  * // `initialize` invokes `createApplication` once
  */
 function once(func) {
-  return before(func, 2);
+  return before(2, func);
 }
 
 module.exports = once;

function/partial.js

@@ -1,6 +1,4 @@
-var baseSlice = require('../internal/baseSlice'),
-    createWrapper = require('../internal/createWrapper'),
-    replaceHolders = require('../internal/replaceHolders');
+var createPartial = require('../internal/createPartial');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var PARTIAL_FLAG = 32;
@@ -13,14 +11,14 @@ var PARTIAL_FLAG = 32;
  * The `_.partial.placeholder` value, which defaults to `_` in monolithic
  * builds, may be used as a placeholder for partially applied arguments.
  *
- * **Note:** This method does not set the `length` property of partially
+ * **Note:** This method does not set the "length" property of partially
  * applied functions.
  *
  * @static
  * @memberOf _
  * @category Function
  * @param {Function} func The function to partially apply arguments to.
- * @param {...*} [args] The arguments to be partially applied.
+ * @param {...*} [partials] The arguments to be partially applied.
  * @returns {Function} Returns the new partially applied function.
  * @example
  *
@@ -37,12 +35,7 @@ var PARTIAL_FLAG = 32;
  * greetFred('hi');
  * // => 'hi fred'
  */
-function partial(func) {
-  var partials = baseSlice(arguments, 1),
-      holders = replaceHolders(partials, partial.placeholder);
-
-  return createWrapper(func, PARTIAL_FLAG, null, partials, holders);
-}
+var partial = createPartial(PARTIAL_FLAG);
 
 // Assign default placeholders.
 partial.placeholder = {};

function/partialRight.js

@@ -1,6 +1,4 @@
-var baseSlice = require('../internal/baseSlice'),
-    createWrapper = require('../internal/createWrapper'),
-    replaceHolders = require('../internal/replaceHolders');
+var createPartial = require('../internal/createPartial');
 
 /** Used to compose bitmasks for wrapper metadata. */
 var PARTIAL_RIGHT_FLAG = 64;
@@ -12,14 +10,14 @@ var PARTIAL_RIGHT_FLAG = 64;
  * The `_.partialRight.placeholder` value, which defaults to `_` in monolithic
  * builds, may be used as a placeholder for partially applied arguments.
  *
- * **Note:** This method does not set the `length` property of partially
+ * **Note:** This method does not set the "length" property of partially
  * applied functions.
  *
  * @static
  * @memberOf _
  * @category Function
  * @param {Function} func The function to partially apply arguments to.
- * @param {...*} [args] The arguments to be partially applied.
+ * @param {...*} [partials] The arguments to be partially applied.
  * @returns {Function} Returns the new partially applied function.
  * @example
  *
@@ -36,12 +34,7 @@ var PARTIAL_RIGHT_FLAG = 64;
  * sayHelloTo('fred');
  * // => 'hello fred'
  */
-function partialRight(func) {
-  var partials = baseSlice(arguments, 1),
-      holders = replaceHolders(partials, partialRight.placeholder);
-
-  return createWrapper(func, PARTIAL_RIGHT_FLAG, null, partials, holders);
-}
+var partialRight = createPartial(PARTIAL_RIGHT_FLAG);
 
 // Assign default placeholders.
 partialRight.placeholder = {};

function/rearg.js

@@ -1,8 +1,9 @@
 var baseFlatten = require('../internal/baseFlatten'),
-    createWrapper = require('../internal/createWrapper');
+    createWrapper = require('../internal/createWrapper'),
+    restParam = require('./restParam');
 
 /** Used to compose bitmasks for wrapper metadata. */
-var REARG_FLAG = 128;
+var REARG_FLAG = 256;
 
 /**
  * Creates a function that invokes `func` with arguments arranged according
@@ -32,9 +33,8 @@ var REARG_FLAG = 128;
  * }, [1, 2, 3]);
  * // => [3, 6, 9]
  */
-function rearg(func) {
-  var indexes = baseFlatten(arguments, false, false, 1);
-  return createWrapper(func, REARG_FLAG, null, null, null, indexes);
-}
+var rearg = restParam(function(func, indexes) {
+  return createWrapper(func, REARG_FLAG, null, null, null, baseFlatten(indexes));
+});
 
 module.exports = rearg;

function/restParam.js

@@ -0,0 +1,58 @@
+/** Used as the `TypeError` message for "Functions" methods. */
+var FUNC_ERROR_TEXT = 'Expected a function';
+
+/* Native method references for those with the same name as other `lodash` methods. */
+var nativeMax = Math.max;
+
+/**
+ * Creates a function that invokes `func` with the `this` binding of the
+ * created function and arguments from `start` and beyond provided as an array.
+ *
+ * **Note:** This method is based on the [rest parameter](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters).
+ *
+ * @static
+ * @memberOf _
+ * @category Function
+ * @param {Function} func The function to apply a rest parameter to.
+ * @param {number} [start=func.length-1] The start position of the rest parameter.
+ * @returns {Function} Returns the new function.
+ * @example
+ *
+ * var say = _.restParam(function(what, names) {
+ *   return what + ' ' + _.initial(names).join(', ') +
+ *     (_.size(names) > 1 ? ', & ' : '') + _.last(names);
+ * });
+ *
+ * say('hello', 'fred', 'barney', 'pebbles');
+ * // => 'hello fred, barney, & pebbles'
+ */
+function restParam(func, start) {
+  if (typeof func != 'function') {
+    throw new TypeError(FUNC_ERROR_TEXT);
+  }
+  start = nativeMax(start === undefined ? (func.length - 1) : (+start || 0), 0);
+  return function() {
+    var args = arguments,
+        index = -1,
+        length = nativeMax(args.length - start, 0),
+        rest = Array(length);
+
+    while (++index < length) {
+      rest[index] = args[start + index];
+    }
+    switch (start) {
+      case 0: return func.call(this, rest);
+      case 1: return func.call(this, args[0], rest);
+      case 2: return func.call(this, args[0], args[1], rest);
+    }
+    var otherArgs = Array(start + 1);
+    index = -1;
+    while (++index < start) {
+      otherArgs[index] = args[index];
+    }
+    otherArgs[start] = rest;
+    return func.apply(this, otherArgs);
+  };
+}
+
+module.exports = restParam;

function/spread.js

@@ -2,23 +2,24 @@
 var FUNC_ERROR_TEXT = 'Expected a function';
 
 /**
- * Creates a function that invokes `func` with the `this` binding of the
- * created function and the array of arguments provided to the created
- * function much like [Function#apply](http://es5.github.io/#x15.3.4.3).
+ * Creates a function that invokes `func` with the `this` binding of the created
+ * function and an array of arguments much like [`Function#apply`](https://es5.github.io/#x15.3.4.3).
+ *
+ * **Note:** This method is based on the [spread operator](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator).
  *
  * @static
  * @memberOf _
  * @category Function
  * @param {Function} func The function to spread arguments over.
- * @returns {*} Returns the new function.
+ * @returns {Function} Returns the new function.
  * @example
  *
- * var spread = _.spread(function(who, what) {
+ * var say = _.spread(function(who, what) {
  *   return who + ' says ' + what;
  * });
  *
- * spread(['Fred', 'hello']);
- * // => 'Fred says hello'
+ * say(['fred', 'hello']);
+ * // => 'fred says hello'
  *
  * // with a Promise
  * var numbers = Promise.all([

internal/arrayEach.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.forEach` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayEachRight.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.forEachRight` for arrays without support for
- * callback shorthands or `this` binding.
+ * callback shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayEvery.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.every` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayFilter.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.filter` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayMap.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.map` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayReduce.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.reduce` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arrayReduceRight.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.reduceRight` for arrays without support for
- * callback shorthands or `this` binding.
+ * callback shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arraySome.js

@@ -1,6 +1,6 @@
 /**
  * A specialized version of `_.some` for arrays without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array} array The array to iterate over.

internal/arraySum.js

@@ -0,0 +1,18 @@
+/**
+ * A specialized version of `_.sum` for arrays without support for iteratees.
+ *
+ * @private
+ * @param {Array} array The array to iterate over.
+ * @returns {number} Returns the sum.
+ */
+function arraySum(array) {
+  var length = array.length,
+      result = 0;
+
+  while (length--) {
+    result += +array[length] || 0;
+  }
+  return result;
+}
+
+module.exports = arraySum;

internal/assignDefaults.js

@@ -7,7 +7,7 @@
  * @returns {*} Returns the value to assign to the destination object.
  */
 function assignDefaults(objectValue, sourceValue) {
-  return typeof objectValue == 'undefined' ? sourceValue : objectValue;
+  return objectValue === undefined ? sourceValue : objectValue;
 }
 
 module.exports = assignDefaults;

internal/assignOwnDefaults.js

@@ -7,7 +7,7 @@ var hasOwnProperty = objectProto.hasOwnProperty;
 /**
  * Used by `_.template` to customize its `_.assign` use.
  *
- * **Note:** This method is like `assignDefaults` except that it ignores
+ * **Note:** This function is like `assignDefaults` except that it ignores
  * inherited property values when checking if a property is `undefined`.
  *
  * @private
@@ -18,7 +18,7 @@ var hasOwnProperty = objectProto.hasOwnProperty;
  * @returns {*} Returns the value to assign to the destination object.
  */
 function assignOwnDefaults(objectValue, sourceValue, key, object) {
-  return (typeof objectValue == 'undefined' || !hasOwnProperty.call(object, key))
+  return (objectValue === undefined || !hasOwnProperty.call(object, key))
     ? sourceValue
     : objectValue;
 }

internal/assignWith.js

@@ -0,0 +1,41 @@
+var getSymbols = require('./getSymbols'),
+    keys = require('../object/keys');
+
+/** Used for native method references. */
+var arrayProto = Array.prototype;
+
+/** Native method references. */
+var push = arrayProto.push;
+
+/**
+ * A specialized version of `_.assign` for customizing assigned values without
+ * support for argument juggling, multiple sources, and `this` binding `customizer`
+ * functions.
+ *
+ * @private
+ * @param {Object} object The destination object.
+ * @param {Object} source The source object.
+ * @param {Function} customizer The function to customize assigned values.
+ * @returns {Object} Returns `object`.
+ */
+function assignWith(object, source, customizer) {
+  var props = keys(source);
+  push.apply(props, getSymbols(source));
+
+  var index = -1,
+      length = props.length;
+
+  while (++index < length) {
+    var key = props[index],
+        value = object[key],
+        result = customizer(value, source[key], key, object, source);
+
+    if ((result === result ? (result !== value) : (value === value)) ||
+        (value === undefined && !(key in object))) {
+      object[key] = result;
+    }
+  }
+  return object;
+}
+
+module.exports = assignWith;

internal/baseAssign.js

@@ -1,35 +1,40 @@
 var baseCopy = require('./baseCopy'),
+    getSymbols = require('./getSymbols'),
+    isNative = require('../lang/isNative'),
     keys = require('../object/keys');
 
+/** Native method references. */
+var preventExtensions = isNative(Object.preventExtensions = Object.preventExtensions) && preventExtensions;
+
+/** Used as `baseAssign`. */
+var nativeAssign = (function() {
+  // Avoid `Object.assign` in Firefox 34-37 which have an early implementation
+  // with a now defunct try/catch behavior. See https://bugzilla.mozilla.org/show_bug.cgi?id=1103344
+  // for more details.
+  //
+  // Use `Object.preventExtensions` on a plain object instead of simply using
+  // `Object('x')` because Chrome and IE fail to throw an error when attempting
+  // to assign values to readonly indexes of strings in strict mode.
+  var object = { '1': 0 },
+      func = preventExtensions && isNative(func = Object.assign) && func;
+
+  try { func(preventExtensions(object), 'xo'); } catch(e) {}
+  return !object[1] && func;
+}());
+
 /**
  * The base implementation of `_.assign` without support for argument juggling,
- * multiple sources, and `this` binding `customizer` functions.
+ * multiple sources, and `customizer` functions.
  *
  * @private
  * @param {Object} object The destination object.
  * @param {Object} source The source object.
- * @param {Function} [customizer] The function to customize assigning values.
- * @returns {Object} Returns the destination object.
+ * @returns {Object} Returns `object`.
  */
-function baseAssign(object, source, customizer) {
-  var props = keys(source);
-  if (!customizer) {
-    return baseCopy(source, object, props);
-  }
-  var index = -1,
-      length = props.length;
-
-  while (++index < length) {
-    var key = props[index],
-        value = object[key],
-        result = customizer(value, source[key], key, object, source);
-
-    if ((result === result ? (result !== value) : (value === value)) ||
-        (typeof value == 'undefined' && !(key in object))) {
-      object[key] = result;
-    }
-  }
-  return object;
-}
+var baseAssign = nativeAssign || function(object, source) {
+  return source == null
+    ? object
+    : baseCopy(source, getSymbols(source), baseCopy(source, keys(source), object));
+};
 
 module.exports = baseAssign;

internal/baseAt.js

@@ -2,12 +2,12 @@ var isIndex = require('./isIndex'),
     isLength = require('./isLength');
 
 /**
- * The base implementation of `_.at` without support for strings and individual
- * key arguments.
+ * The base implementation of `_.at` without support for string collections
+ * and individual key arguments.
  *
  * @private
  * @param {Array|Object} collection The collection to iterate over.
- * @param {number[]|string[]} [props] The property names or indexes of elements to pick.
+ * @param {number[]|string[]} props The property names or indexes of elements to pick.
  * @returns {Array} Returns the new array of picked elements.
  */
 function baseAt(collection, props) {
@@ -20,7 +20,6 @@ function baseAt(collection, props) {
   while(++index < propsLength) {
     var key = props[index];
     if (isArr) {
-      key = parseFloat(key);
       result[index] = isIndex(key, length) ? collection[key] : undefined;
     } else {
       result[index] = collection[key];

internal/baseBindAll.js

@@ -1,26 +0,0 @@
-var createWrapper = require('./createWrapper');
-
-/** Used to compose bitmasks for wrapper metadata. */
-var BIND_FLAG = 1;
-
-/**
- * The base implementation of `_.bindAll` without support for individual
- * method name arguments.
- *
- * @private
- * @param {Object} object The object to bind and assign the bound methods to.
- * @param {string[]} methodNames The object method names to bind.
- * @returns {Object} Returns `object`.
- */
-function baseBindAll(object, methodNames) {
-  var index = -1,
-      length = methodNames.length;
-
-  while (++index < length) {
-    var key = methodNames[index];
-    object[key] = createWrapper(object[key], BIND_FLAG, object);
-  }
-  return object;
-}
-
-module.exports = baseBindAll;

internal/baseCallback.js

@@ -1,9 +1,8 @@
 var baseMatches = require('./baseMatches'),
     baseMatchesProperty = require('./baseMatchesProperty'),
-    baseProperty = require('./baseProperty'),
     bindCallback = require('./bindCallback'),
     identity = require('../utility/identity'),
-    isBindable = require('./isBindable');
+    property = require('../utility/property');
 
 /**
  * The base implementation of `_.callback` which supports specifying the
@@ -18,9 +17,9 @@ var baseMatches = require('./baseMatches'),
 function baseCallback(func, thisArg, argCount) {
   var type = typeof func;
   if (type == 'function') {
-    return (typeof thisArg != 'undefined' && isBindable(func))
-      ? bindCallback(func, thisArg, argCount)
-      : func;
+    return thisArg === undefined
+      ? func
+      : bindCallback(func, thisArg, argCount);
   }
   if (func == null) {
     return identity;
@@ -28,9 +27,9 @@ function baseCallback(func, thisArg, argCount) {
   if (type == 'object') {
     return baseMatches(func);
   }
-  return typeof thisArg == 'undefined'
-    ? baseProperty(func + '')
-    : baseMatchesProperty(func + '', thisArg);
+  return thisArg === undefined
+    ? property(func)
+    : baseMatchesProperty(func, thisArg);
 }
 
 module.exports = baseCallback;

internal/baseClone.js

@@ -1,13 +1,12 @@
 var arrayCopy = require('./arrayCopy'),
     arrayEach = require('./arrayEach'),
-    baseCopy = require('./baseCopy'),
+    baseAssign = require('./baseAssign'),
     baseForOwn = require('./baseForOwn'),
     initCloneArray = require('./initCloneArray'),
     initCloneByTag = require('./initCloneByTag'),
     initCloneObject = require('./initCloneObject'),
     isArray = require('../lang/isArray'),
-    isObject = require('../lang/isObject'),
-    keys = require('../object/keys');
+    isObject = require('../lang/isObject');
 
 /** `Object#toString` result references. */
 var argsTag = '[object Arguments]',
@@ -54,9 +53,8 @@ cloneableTags[weakMapTag] = false;
 var objectProto = Object.prototype;
 
 /**
- * Used to resolve the `toStringTag` of values.
- * See the [ES spec](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
- * for more details.
+ * Used to resolve the [`toStringTag`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
+ * of values.
  */
 var objToString = objectProto.toString;
 
@@ -79,7 +77,7 @@ function baseClone(value, isDeep, customizer, key, object, stackA, stackB) {
   if (customizer) {
     result = object ? customizer(value, key, object) : customizer(value);
   }
-  if (typeof result != 'undefined') {
+  if (result !== undefined) {
     return result;
   }
   if (!isObject(value)) {
@@ -98,7 +96,7 @@ function baseClone(value, isDeep, customizer, key, object, stackA, stackB) {
     if (tag == objectTag || tag == argsTag || (isFunc && !object)) {
       result = initCloneObject(isFunc ? {} : value);
       if (!isDeep) {
-        return baseCopy(value, result, keys(value));
+        return baseAssign(result, value);
       }
     } else {
       return cloneableTags[tag]

internal/baseCompareAscending.js

@@ -12,10 +12,10 @@ function baseCompareAscending(value, other) {
     var valIsReflexive = value === value,
         othIsReflexive = other === other;
 
-    if (value > other || !valIsReflexive || (typeof value == 'undefined' && othIsReflexive)) {
+    if (value > other || !valIsReflexive || (value === undefined && othIsReflexive)) {
       return 1;
     }
-    if (value < other || !othIsReflexive || (typeof other == 'undefined' && valIsReflexive)) {
+    if (value < other || !othIsReflexive || (other === undefined && valIsReflexive)) {
       return -1;
     }
   }

internal/baseCopy.js

@@ -1,17 +1,15 @@
 /**
- * Copies the properties of `source` to `object`.
+ * Copies properties of `source` to `object`.
  *
  * @private
  * @param {Object} source The object to copy properties from.
- * @param {Object} [object={}] The object to copy properties to.
  * @param {Array} props The property names to copy.
+ * @param {Object} [object={}] The object to copy properties to.
  * @returns {Object} Returns `object`.
  */
-function baseCopy(source, object, props) {
-  if (!props) {
-    props = object;
-    object = {};
-  }
+function baseCopy(source, props, object) {
+  object || (object = {});
+
   var index = -1,
       length = props.length;
 

internal/baseDelay.js

@@ -1,5 +1,3 @@
-var baseSlice = require('./baseSlice');
-
 /** Used as the `TypeError` message for "Functions" methods. */
 var FUNC_ERROR_TEXT = 'Expected a function';
 
@@ -10,14 +8,14 @@ var FUNC_ERROR_TEXT = 'Expected a function';
  * @private
  * @param {Function} func The function to delay.
  * @param {number} wait The number of milliseconds to delay invocation.
- * @param {Object} args The `arguments` object to slice and provide to `func`.
+ * @param {Object} args The arguments provide to `func`.
  * @returns {number} Returns the timer id.
  */
-function baseDelay(func, wait, args, fromIndex) {
+function baseDelay(func, wait, args) {
   if (typeof func != 'function') {
     throw new TypeError(FUNC_ERROR_TEXT);
   }
-  return setTimeout(function() { func.apply(undefined, baseSlice(args, fromIndex)); }, wait);
+  return setTimeout(function() { func.apply(undefined, args); }, wait);
 }
 
 module.exports = baseDelay;

internal/baseEach.js

@@ -1,6 +1,5 @@
 var baseForOwn = require('./baseForOwn'),
-    isLength = require('./isLength'),
-    toObject = require('./toObject');
+    createBaseEach = require('./createBaseEach');
 
 /**
  * The base implementation of `_.forEach` without support for callback
@@ -11,20 +10,6 @@ var baseForOwn = require('./baseForOwn'),
  * @param {Function} iteratee The function invoked per iteration.
  * @returns {Array|Object|string} Returns `collection`.
  */
-function baseEach(collection, iteratee) {
-  var length = collection ? collection.length : 0;
-  if (!isLength(length)) {
-    return baseForOwn(collection, iteratee);
-  }
-  var index = -1,
-      iterable = toObject(collection);
-
-  while (++index < length) {
-    if (iteratee(iterable[index], index, iterable) === false) {
-      break;
-    }
-  }
-  return collection;
-}
+var baseEach = createBaseEach(baseForOwn);
 
 module.exports = baseEach;

internal/baseEachRight.js

@@ -1,6 +1,5 @@
 var baseForOwnRight = require('./baseForOwnRight'),
-    isLength = require('./isLength'),
-    toObject = require('./toObject');
+    createBaseEach = require('./createBaseEach');
 
 /**
  * The base implementation of `_.forEachRight` without support for callback
@@ -11,18 +10,6 @@ var baseForOwnRight = require('./baseForOwnRight'),
  * @param {Function} iteratee The function invoked per iteration.
  * @returns {Array|Object|string} Returns `collection`.
  */
-function baseEachRight(collection, iteratee) {
-  var length = collection ? collection.length : 0;
-  if (!isLength(length)) {
-    return baseForOwnRight(collection, iteratee);
-  }
-  var iterable = toObject(collection);
-  while (length--) {
-    if (iteratee(iterable[length], length, iterable) === false) {
-      break;
-    }
-  }
-  return collection;
-}
+var baseEachRight = createBaseEach(baseForOwnRight, true);
 
 module.exports = baseEachRight;

internal/baseEvery.js

@@ -2,7 +2,7 @@ var baseEach = require('./baseEach');
 
 /**
  * The base implementation of `_.every` without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array|Object|string} collection The collection to iterate over.

internal/baseFill.js

@@ -15,7 +15,7 @@ function baseFill(array, value, start, end) {
   if (start < 0) {
     start = -start > length ? 0 : (length + start);
   }
-  end = (typeof end == 'undefined' || end > length) ? length : (+end || 0);
+  end = (end === undefined || end > length) ? length : (+end || 0);
   if (end < 0) {
     end += length;
   }

internal/baseFilter.js

@@ -2,7 +2,7 @@ var baseEach = require('./baseEach');
 
 /**
  * The base implementation of `_.filter` without support for callback
- * shorthands or `this` binding.
+ * shorthands and `this` binding.
  *
  * @private
  * @param {Array|Object|string} collection The collection to iterate over.

internal/baseFindIndex.js

@@ -0,0 +1,23 @@
+/**
+ * The base implementation of `_.findIndex` and `_.findLastIndex` without
+ * support for callback shorthands and `this` binding.
+ *
+ * @private
+ * @param {Array} array The array to search.
+ * @param {Function} predicate The function invoked per iteration.
+ * @param {boolean} [fromRight] Specify iterating from right to left.
+ * @returns {number} Returns the index of the matched value, else `-1`.
+ */
+function baseFindIndex(array, predicate, fromRight) {
+  var length = array.length,
+      index = fromRight ? length : -1;
+
+  while ((fromRight ? index-- : ++index < length)) {
+    if (predicate(array[index], index, array)) {
+      return index;
+    }
+  }
+  return -1;
+}
+
+module.exports = baseFindIndex;

internal/baseFlatten.js

@@ -11,11 +11,10 @@ var isArguments = require('../lang/isArguments'),
  * @param {Array} array The array to flatten.
  * @param {boolean} isDeep Specify a deep flatten.
  * @param {boolean} isStrict Restrict flattening to arrays and `arguments` objects.
- * @param {number} fromIndex The index to start from.
  * @returns {Array} Returns the new flattened array.
  */
-function baseFlatten(array, isDeep, isStrict, fromIndex) {
-  var index = fromIndex - 1,
+function baseFlatten(array, isDeep, isStrict) {
+  var index = -1,
       length = array.length,
       resIndex = -1,
       result = [];
@@ -26,7 +25,7 @@ function baseFlatten(array, isDeep, isStrict, fromIndex) {
     if (isObjectLike(value) && isLength(value.length) && (isArray(value) || isArguments(value))) {
       if (isDeep) {
         // Recursively flatten arrays (susceptible to call stack limits).
-        value = baseFlatten(value, isDeep, isStrict, 0);
+        value = baseFlatten(value, isDeep, isStrict);
       }
       var valIndex = -1,
           valLength = value.length;

internal/baseFor.js

@@ -1,9 +1,9 @@
-var toObject = require('./toObject');
+var createBaseFor = require('./createBaseFor');
 
 /**
  * The base implementation of `baseForIn` and `baseForOwn` which iterates
  * over `object` properties returned by `keysFunc` invoking `iteratee` for
- * each property. Iterator functions may exit iteration early by explicitly
+ * each property. Iteratee functions may exit iteration early by explicitly
  * returning `false`.
  *
  * @private
@@ -12,19 +12,6 @@ var toObject = require('./toObject');
  * @param {Function} keysFunc The function to get the keys of `object`.
  * @returns {Object} Returns `object`.
  */
-function baseFor(object, iteratee, keysFunc) {
-  var index = -1,
-      iterable = toObject(object),
-      props = keysFunc(object),
-      length = props.length;
-
-  while (++index < length) {
-    var key = props[index];
-    if (iteratee(iterable[key], key, iterable) === false) {
-      break;
-    }
-  }
-  return object;
-}
+var baseFor = createBaseFor();
 
 module.exports = baseFor;

internal/baseForRight.js

@@ -1,4 +1,4 @@
-var toObject = require('./toObject');
+var createBaseFor = require('./createBaseFor');
 
 /**
  * This function is like `baseFor` except that it iterates over properties
@@ -10,18 +10,6 @@ var toObject = require('./toObject');
  * @param {Function} keysFunc The function to get the keys of `object`.
  * @returns {Object} Returns `object`.
  */
-function baseForRight(object, iteratee, keysFunc) {
-  var iterable = toObject(object),
-      props = keysFunc(object),
-      length = props.length;
-
-  while (length--) {
-    var key = props[length];
-    if (iteratee(iterable[key], key, iterable) === false) {
-      break;
-    }
-  }
-  return object;
-}
+var baseForRight = createBaseFor(true);
 
 module.exports = baseForRight;