Bump to v3.8.0.

README.md

@@ -1,4 +1,4 @@
-# lodash v3.7.0
+# lodash v3.8.0
 
 The [modern build](https://github.com/lodash/lodash/wiki/Build-Differences) of [lodash](https://lodash.com/) exported as [AMD](https://github.com/amdjs/amdjs-api/wiki/AMD) modules.
 
@@ -13,8 +13,8 @@ $ lodash modern exports=amd -d -o ./main.js
 Using bower or volo:
 
 ```bash
-$ bower i lodash#3.7.0-amd
-$ volo add lodash/3.7.0-amd
+$ bower i lodash#3.8.0-amd
+$ volo add lodash/3.8.0-amd
 ```
 
 Defining a build as `'lodash'`.

array.js

@@ -1,4 +1,4 @@
-define(['./array/chunk', './array/compact', './array/difference', './array/drop', './array/dropRight', './array/dropRightWhile', './array/dropWhile', './array/fill', './array/findIndex', './array/findLastIndex', './array/first', './array/flatten', './array/flattenDeep', './array/head', './array/indexOf', './array/initial', './array/intersection', './array/last', './array/lastIndexOf', './array/object', './array/pull', './array/pullAt', './array/remove', './array/rest', './array/slice', './array/sortedIndex', './array/sortedLastIndex', './array/tail', './array/take', './array/takeRight', './array/takeRightWhile', './array/takeWhile', './array/union', './array/uniq', './array/unique', './array/unzip', './array/without', './array/xor', './array/zip', './array/zipObject'], function(chunk, compact, difference, drop, dropRight, dropRightWhile, dropWhile, fill, findIndex, findLastIndex, first, flatten, flattenDeep, head, indexOf, initial, intersection, last, lastIndexOf, object, pull, pullAt, remove, rest, slice, sortedIndex, sortedLastIndex, tail, take, takeRight, takeRightWhile, takeWhile, union, uniq, unique, unzip, without, xor, zip, zipObject) {
+define(['./array/chunk', './array/compact', './array/difference', './array/drop', './array/dropRight', './array/dropRightWhile', './array/dropWhile', './array/fill', './array/findIndex', './array/findLastIndex', './array/first', './array/flatten', './array/flattenDeep', './array/head', './array/indexOf', './array/initial', './array/intersection', './array/last', './array/lastIndexOf', './array/object', './array/pull', './array/pullAt', './array/remove', './array/rest', './array/slice', './array/sortedIndex', './array/sortedLastIndex', './array/tail', './array/take', './array/takeRight', './array/takeRightWhile', './array/takeWhile', './array/union', './array/uniq', './array/unique', './array/unzip', './array/unzipWith', './array/without', './array/xor', './array/zip', './array/zipObject', './array/zipWith'], function(chunk, compact, difference, drop, dropRight, dropRightWhile, dropWhile, fill, findIndex, findLastIndex, first, flatten, flattenDeep, head, indexOf, initial, intersection, last, lastIndexOf, object, pull, pullAt, remove, rest, slice, sortedIndex, sortedLastIndex, tail, take, takeRight, takeRightWhile, takeWhile, union, uniq, unique, unzip, unzipWith, without, xor, zip, zipObject, zipWith) {
   return {
     'chunk': chunk,
     'compact': compact,
@@ -36,9 +36,11 @@ define(['./array/chunk', './array/compact', './array/difference', './array/drop'
     'uniq': uniq,
     'unique': unique,
     'unzip': unzip,
+    'unzipWith': unzipWith,
     'without': without,
     'xor': xor,
     'zip': zip,
-    'zipObject': zipObject
+    'zipObject': zipObject,
+    'zipWith': zipWith
   };
 });

array/difference.js

@@ -1,12 +1,9 @@
-define(['../internal/baseDifference', '../internal/baseFlatten', '../lang/isArguments', '../lang/isArray', '../function/restParam'], function(baseDifference, baseFlatten, isArguments, isArray, restParam) {
+define(['../internal/baseDifference', '../internal/baseFlatten', '../internal/isArrayLike', '../function/restParam'], function(baseDifference, baseFlatten, isArrayLike, restParam) {
 
   /**
    * Creates an array excluding all values of the provided arrays using
-   * `SameValueZero` for equality comparisons.
-   *
-   * **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`.
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons.
    *
    * @static
    * @memberOf _
@@ -20,7 +17,7 @@ define(['../internal/baseDifference', '../internal/baseFlatten', '../lang/isArgu
    * // => [1, 3]
    */
   var difference = restParam(function(array, values) {
-    return (isArray(array) || isArguments(array))
+    return isArrayLike(array)
       ? baseDifference(array, baseFlatten(values, false, true))
       : [];
   });

array/indexOf.js

@@ -5,13 +5,10 @@ define(['../internal/baseIndexOf', '../internal/binaryIndex'], function(baseInde
 
   /**
    * Gets the index at which the first occurrence of `value` is found in `array`
-   * using `SameValueZero` for equality comparisons. If `fromIndex` is negative,
-   * 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`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
-   * comparisons are like strict equality comparisons, e.g. `===`, except that
-   * `NaN` matches `NaN`.
+   * using [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons. If `fromIndex` is negative, it is used as the offset
+   * from the end of `array`. If `array` is sorted providing `true` for `fromIndex`
+   * performs a faster binary search.
    *
    * @static
    * @memberOf _

array/intersection.js

@@ -1,13 +1,10 @@
-define(['../internal/baseIndexOf', '../internal/cacheIndexOf', '../internal/createCache', '../lang/isArguments', '../lang/isArray'], function(baseIndexOf, cacheIndexOf, createCache, isArguments, isArray) {
+define(['../internal/baseIndexOf', '../internal/cacheIndexOf', '../internal/createCache', '../internal/isArrayLike'], function(baseIndexOf, cacheIndexOf, createCache, isArrayLike) {
 
   /**
-   * Creates an array of unique values in all provided arrays using `SameValueZero`
+   * Creates an array of unique values in all provided arrays using
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
    * for equality comparisons.
    *
-   * **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 _
    * @category Array
@@ -28,7 +25,7 @@ define(['../internal/baseIndexOf', '../internal/cacheIndexOf', '../internal/crea
 
     while (++argsIndex < argsLength) {
       var value = arguments[argsIndex];
-      if (isArray(value) || isArguments(value)) {
+      if (isArrayLike(value)) {
         args.push(value);
         caches.push((isCommon && value.length >= 120) ? createCache(argsIndex && value) : null);
       }

array/pull.js

@@ -7,14 +7,11 @@ define(['../internal/baseIndexOf'], function(baseIndexOf) {
   var splice = arrayProto.splice;
 
   /**
-   * Removes all provided values from `array` using `SameValueZero` for equality
-   * comparisons.
+   * Removes all provided values from `array` using
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons.
    *
-   * **Notes:**
-   *  - 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`
+   * **Note:** Unlike `_.without`, this method mutates `array`.
    *
    * @static
    * @memberOf _

array/pullAt.js

@@ -26,7 +26,6 @@ define(['../internal/baseAt', '../internal/baseCompareAscending', '../internal/b
    * // => [10, 20]
    */
   var pullAt = restParam(function(array, indexes) {
-    array || (array = []);
     indexes = baseFlatten(indexes);
 
     var result = baseAt(array, indexes);

array/union.js

@@ -2,11 +2,8 @@ define(['../internal/baseFlatten', '../internal/baseUniq', '../function/restPara
 
   /**
    * Creates an array of unique values, in order, of the provided arrays using
-   * `SameValueZero` for equality comparisons.
-   *
-   * **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`.
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons.
    *
    * @static
    * @memberOf _

array/uniq.js

@@ -1,8 +1,9 @@
 define(['../internal/baseCallback', '../internal/baseUniq', '../internal/isIterateeCall', '../internal/sortedUniq'], function(baseCallback, baseUniq, isIterateeCall, sortedUniq) {
 
   /**
-   * Creates a duplicate-free version of an array, using `SameValueZero` for
-   * equality comparisons, in which only the first occurence of each element
+   * Creates a duplicate-free version of an array, using
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-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
@@ -20,10 +21,6 @@ define(['../internal/baseCallback', '../internal/baseUniq', '../internal/isItera
    * callback returns `true` for elements that have the properties of the given
    * object, else `false`.
    *
-   * **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 _
    * @alias unique

array/unzip.js

@@ -1,8 +1,11 @@
-define(['../internal/arrayMap', '../internal/arrayMax', '../internal/baseProperty', '../internal/getLength'], function(arrayMap, arrayMax, baseProperty, getLength) {
+define(['../internal/arrayFilter', '../internal/arrayMap', '../internal/baseProperty', '../internal/isArrayLike'], function(arrayFilter, arrayMap, baseProperty, isArrayLike) {
+
+  /* Native method references for those with the same name as other `lodash` methods. */
+  var nativeMax = Math.max;
 
   /**
    * This method is like `_.zip` except that it accepts an array of grouped
-   * elements and creates an array regrouping the elements to their pre-`_.zip`
+   * elements and creates an array regrouping the elements to their pre-zip
    * configuration.
    *
    * @static
@@ -19,10 +22,19 @@ define(['../internal/arrayMap', '../internal/arrayMax', '../internal/basePropert
    * // => [['fred', 'barney'], [30, 40], [true, false]]
    */
   function unzip(array) {
+    if (!(array && array.length)) {
+      return [];
+    }
     var index = -1,
-        length = (array && array.length && arrayMax(arrayMap(array, getLength))) >>> 0,
-        result = Array(length);
+        length = 0;
 
+    array = arrayFilter(array, function(group) {
+      if (isArrayLike(group)) {
+        length = nativeMax(group.length, length);
+        return true;
+      }
+    });
+    var result = Array(length);
     while (++index < length) {
       result[index] = arrayMap(array, baseProperty(index));
     }

array/unzipWith.js

@@ -0,0 +1,42 @@
+define(['../internal/arrayMap', '../internal/arrayReduce', '../internal/bindCallback', './unzip'], function(arrayMap, arrayReduce, bindCallback, unzip) {
+
+  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
+  var undefined;
+
+  /**
+   * This method is like `_.unzip` except that it accepts an iteratee to specify
+   * how regrouped values should be combined. The `iteratee` is bound to `thisArg`
+   * and invoked with four arguments: (accumulator, value, index, group).
+   *
+   * @static
+   * @memberOf _
+   * @category Array
+   * @param {Array} array The array of grouped elements to process.
+   * @param {Function} [iteratee] The function to combine regrouped values.
+   * @param {*} [thisArg] The `this` binding of `iteratee`.
+   * @returns {Array} Returns the new array of regrouped elements.
+   * @example
+   *
+   * var zipped = _.zip([1, 2], [10, 20], [100, 200]);
+   * // => [[1, 10, 100], [2, 20, 200]]
+   *
+   * _.unzipWith(zipped, _.add);
+   * // => [3, 30, 300]
+   */
+  function unzipWith(array, iteratee, thisArg) {
+    var length = array ? array.length : 0;
+    if (!length) {
+      return [];
+    }
+    var result = unzip(array);
+    if (iteratee == null) {
+      return result;
+    }
+    iteratee = bindCallback(iteratee, thisArg, 4);
+    return arrayMap(result, function(group) {
+      return arrayReduce(group, iteratee, undefined, true);
+    });
+  }
+
+  return unzipWith;
+});

array/without.js

@@ -1,12 +1,9 @@
-define(['../internal/baseDifference', '../lang/isArguments', '../lang/isArray', '../function/restParam'], function(baseDifference, isArguments, isArray, restParam) {
+define(['../internal/baseDifference', '../internal/isArrayLike', '../function/restParam'], function(baseDifference, isArrayLike, restParam) {
 
   /**
-   * Creates an array excluding all provided values using `SameValueZero` for
-   * equality comparisons.
-   *
-   * **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`.
+   * Creates an array excluding all provided values using
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons.
    *
    * @static
    * @memberOf _
@@ -20,7 +17,7 @@ define(['../internal/baseDifference', '../lang/isArguments', '../lang/isArray',
    * // => [3]
    */
   var without = restParam(function(array, values) {
-    return (isArray(array) || isArguments(array))
+    return isArrayLike(array)
       ? baseDifference(array, values)
       : [];
   });

array/xor.js

@@ -1,4 +1,4 @@
-define(['../internal/baseDifference', '../internal/baseUniq', '../lang/isArguments', '../lang/isArray'], function(baseDifference, baseUniq, isArguments, isArray) {
+define(['../internal/baseDifference', '../internal/baseUniq', '../internal/isArrayLike'], function(baseDifference, baseUniq, isArrayLike) {
 
   /**
    * Creates an array that is the [symmetric difference](https://en.wikipedia.org/wiki/Symmetric_difference)
@@ -20,7 +20,7 @@ define(['../internal/baseDifference', '../internal/baseUniq', '../lang/isArgumen
 
     while (++index < length) {
       var array = arguments[index];
-      if (isArray(array) || isArguments(array)) {
+      if (isArrayLike(array)) {
         var result = result
           ? baseDifference(result, array).concat(baseDifference(array, result))
           : array;

array/zipWith.js

@@ -0,0 +1,39 @@
+define(['../function/restParam', './unzipWith'], function(restParam, unzipWith) {
+
+  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
+  var undefined;
+
+  /**
+   * This method is like `_.zip` except that it accepts an iteratee to specify
+   * how grouped values should be combined. The `iteratee` is bound to `thisArg`
+   * and invoked with four arguments: (accumulator, value, index, group).
+   *
+   * @static
+   * @memberOf _
+   * @category Array
+   * @param {...Array} [arrays] The arrays to process.
+   * @param {Function} [iteratee] The function to combine grouped values.
+   * @param {*} [thisArg] The `this` binding of `iteratee`.
+   * @returns {Array} Returns the new array of grouped elements.
+   * @example
+   *
+   * _.zipWith([1, 2], [10, 20], [100, 200], _.add);
+   * // => [111, 222]
+   */
+  var zipWith = restParam(function(arrays) {
+    var length = arrays.length,
+        iteratee = arrays[length - 2],
+        thisArg = arrays[length - 1];
+
+    if (length > 2 && typeof iteratee == 'function') {
+      length -= 2;
+    } else {
+      iteratee = (length > 1 && typeof thisArg == 'function') ? (--length, thisArg) : undefined;
+      thisArg = undefined;
+    }
+    arrays.length = length;
+    return unzipWith(arrays, iteratee, thisArg);
+  });
+
+  return zipWith;
+});

collection/at.js

@@ -1,4 +1,4 @@
-define(['../internal/baseAt', '../internal/baseFlatten', '../internal/getLength', '../internal/isLength', '../function/restParam', '../internal/toIterable'], function(baseAt, baseFlatten, getLength, isLength, restParam, toIterable) {
+define(['../internal/baseAt', '../internal/baseFlatten', '../function/restParam'], function(baseAt, baseFlatten, restParam) {
 
   /**
    * Creates an array of elements corresponding to the given keys, or indexes,
@@ -21,10 +21,6 @@ define(['../internal/baseAt', '../internal/baseFlatten', '../internal/getLength'
    * // => ['barney', 'pebbles']
    */
   var at = restParam(function(collection, props) {
-    var length = collection ? getLength(collection) : 0;
-    if (isLength(length)) {
-      collection = toIterable(collection);
-    }
     return baseAt(collection, baseFlatten(props));
   });
 

collection/includes.js

@@ -4,13 +4,10 @@ define(['../internal/baseIndexOf', '../internal/getLength', '../lang/isArray', '
   var nativeMax = Math.max;
 
   /**
-   * Checks if `value` is in `collection` using `SameValueZero` for equality
-   * comparisons. If `fromIndex` is negative, it is used as the offset from
-   * the end of `collection`.
-   *
-   * **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`.
+   * Checks if `value` is in `collection` using
+   * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+   * for equality comparisons. If `fromIndex` is negative, it is used as the offset
+   * from the end of `collection`.
    *
    * @static
    * @memberOf _

collection/invoke.js

@@ -1,4 +1,4 @@
-define(['../internal/baseEach', '../internal/getLength', '../internal/invokePath', '../internal/isKey', '../internal/isLength', '../function/restParam'], function(baseEach, getLength, invokePath, isKey, isLength, restParam) {
+define(['../internal/baseEach', '../internal/invokePath', '../internal/isArrayLike', '../internal/isKey', '../function/restParam'], function(baseEach, invokePath, isArrayLike, isKey, restParam) {
 
   /**
    * Invokes the method at `path` on each element in `collection`, returning
@@ -26,8 +26,7 @@ define(['../internal/baseEach', '../internal/getLength', '../internal/invokePath
     var index = -1,
         isFunc = typeof path == 'function',
         isProp = isKey(path),
-        length = getLength(collection),
-        result = isLength(length) ? Array(length) : [];
+        result = isArrayLike(collection) ? Array(collection.length) : [];
 
     baseEach(collection, function(value) {
       var func = isFunc ? path : (isProp && value != null && value[path]);

collection/map.js

@@ -20,10 +20,11 @@ define(['../internal/arrayMap', '../internal/baseCallback', '../internal/baseMap
    * `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`.
    *
    * The guarded methods are:
-   * `ary`, `callback`, `chunk`, `clone`, `create`, `curry`, `curryRight`, `drop`,
-   * `dropRight`, `every`, `fill`, `flatten`, `invert`, `max`, `min`, `parseInt`,
-   * `slice`, `sortBy`, `take`, `takeRight`, `template`, `trim`, `trimLeft`,
-   * `trimRight`, `trunc`, `random`, `range`, `sample`, `some`, `uniq`, and `words`
+   * `ary`, `callback`, `chunk`, `clone`, `create`, `curry`, `curryRight`,
+   * `drop`, `dropRight`, `every`, `fill`, `flatten`, `invert`, `max`, `min`,
+   * `parseInt`, `slice`, `sortBy`, `take`, `takeRight`, `template`, `trim`,
+   * `trimLeft`, `trimRight`, `trunc`, `random`, `range`, `sample`, `some`,
+   * `sum`, `uniq`, and `words`
    *
    * @static
    * @memberOf _

collection/reduceRight.js

@@ -22,7 +22,7 @@ define(['../internal/arrayReduceRight', '../internal/baseEachRight', '../interna
    * }, []);
    * // => [4, 5, 2, 3, 0, 1]
    */
-  var reduceRight =  createReduce(arrayReduceRight, baseEachRight);
+  var reduceRight = createReduce(arrayReduceRight, baseEachRight);
 
   return reduceRight;
 });

collection/reject.js

@@ -4,17 +4,6 @@ define(['../internal/arrayFilter', '../internal/baseCallback', '../internal/base
    * The opposite of `_.filter`; this method returns the elements of `collection`
    * that `predicate` does **not** return truthy for.
    *
-   * If a property name is provided for `predicate` 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
-   * callback returns `true` for elements that have the properties of the given
-   * object, else `false`.
-   *
    * @static
    * @memberOf _
    * @category Collection

internal/baseAssign.js

@@ -1,7 +1,7 @@
 define(['./baseCopy', './getSymbols', '../lang/isNative', '../object/keys'], function(baseCopy, getSymbols, isNative, keys) {
 
   /** Native method references. */
-  var preventExtensions = isNative(Object.preventExtensions = Object.preventExtensions) && preventExtensions;
+  var preventExtensions = isNative(preventExtensions = Object.preventExtensions) && preventExtensions;
 
   /** Used as `baseAssign`. */
   var nativeAssign = (function() {
@@ -11,12 +11,19 @@ define(['./baseCopy', './getSymbols', '../lang/isNative', '../object/keys'], fun
     //
     // 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;
+    // to assign values to readonly indexes of strings.
+    var func = preventExtensions && isNative(func = Object.assign) && func;
+    try {
+      if (func) {
+        var object = preventExtensions({ '1': 0 });
+        object[0] = 1;
+      }
+    } catch(e) {
+      // Only attempt in strict mode.
+      try { func(object, 'xo'); } catch(e) {}
+      return !object[1] && func;
+    }
+    return false;
   }());
 
   /**

internal/baseAt.js

@@ -1,4 +1,4 @@
-define(['./isIndex', './isLength'], function(isIndex, isLength) {
+define(['./isArrayLike', './isIndex'], function(isArrayLike, isIndex) {
 
   /** Used as a safe reference for `undefined` in pre-ES5 environments. */
   var undefined;
@@ -14,8 +14,9 @@ define(['./isIndex', './isLength'], function(isIndex, isLength) {
    */
   function baseAt(collection, props) {
     var index = -1,
-        length = collection.length,
-        isArr = isLength(length),
+        isNil = collection == null,
+        isArr = !isNil && isArrayLike(collection),
+        length = isArr && collection.length,
         propsLength = props.length,
         result = Array(propsLength);
 
@@ -24,7 +25,7 @@ define(['./isIndex', './isLength'], function(isIndex, isLength) {
       if (isArr) {
         result[index] = isIndex(key, length) ? collection[key] : undefined;
       } else {
-        result[index] = collection[key];
+        result[index] = isNil ? undefined : collection[key];
       }
     }
     return result;

internal/baseFlatten.js

@@ -1,4 +1,4 @@
-define(['../lang/isArguments', '../lang/isArray', './isLength', './isObjectLike'], function(isArguments, isArray, isLength, isObjectLike) {
+define(['../lang/isArguments', '../lang/isArray', './isArrayLike', './isObjectLike'], function(isArguments, isArray, isArrayLike, isObjectLike) {
 
   /**
    * The base implementation of `_.flatten` with added support for restricting
@@ -6,8 +6,8 @@ define(['../lang/isArguments', '../lang/isArray', './isLength', './isObjectLike'
    *
    * @private
    * @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 {boolean} [isDeep] Specify a deep flatten.
+   * @param {boolean} [isStrict] Restrict flattening to arrays-like objects.
    * @returns {Array} Returns the new flattened array.
    */
   function baseFlatten(array, isDeep, isStrict) {
@@ -18,8 +18,8 @@ define(['../lang/isArguments', '../lang/isArray', './isLength', './isObjectLike'
 
     while (++index < length) {
       var value = array[index];
-
-      if (isObjectLike(value) && isLength(value.length) && (isArray(value) || isArguments(value))) {
+      if (isObjectLike(value) && isArrayLike(value) &&
+          (isStrict || isArray(value) || isArguments(value))) {
         if (isDeep) {
           // Recursively flatten arrays (susceptible to call stack limits).
           value = baseFlatten(value, isDeep, isStrict);
@@ -27,7 +27,6 @@ define(['../lang/isArguments', '../lang/isArray', './isLength', './isObjectLike'
         var valIndex = -1,
             valLength = value.length;
 
-        result.length += valLength;
         while (++valIndex < valLength) {
           result[++resIndex] = value[valIndex];
         }

internal/baseGet.js

@@ -24,9 +24,9 @@ define(['./toObject'], function(toObject) {
         length = path.length;
 
     while (object != null && ++index < length) {
-      var result = object = object[path[index]];
+      object = object[path[index]];
     }
-    return result;
+    return (index && index == length) ? object : undefined;
   }
 
   return baseGet;

internal/baseIsEqual.js

@@ -16,8 +16,7 @@ define(['./baseIsEqualDeep'], function(baseIsEqualDeep) {
   function baseIsEqual(value, other, customizer, isLoose, stackA, stackB) {
     // Exit early for identical values.
     if (value === other) {
-      // Treat `+0` vs. `-0` as not equal.
-      return value !== 0 || (1 / value == 1 / other);
+      return true;
     }
     var valType = typeof value,
         othType = typeof other;

internal/baseMap.js

@@ -1,4 +1,4 @@
-define(['./baseEach', './getLength', './isLength'], function(baseEach, getLength, isLength) {
+define(['./baseEach', './isArrayLike'], function(baseEach, isArrayLike) {
 
   /**
    * The base implementation of `_.map` without support for callback shorthands
@@ -11,8 +11,7 @@ define(['./baseEach', './getLength', './isLength'], function(baseEach, getLength
    */
   function baseMap(collection, iteratee) {
     var index = -1,
-        length = getLength(collection),
-        result = isLength(length) ? Array(length) : [];
+        result = isArrayLike(collection) ? Array(collection.length) : [];
 
     baseEach(collection, function(value, key, collection) {
       result[++index] = iteratee(value, key, collection);

internal/baseMerge.js

@@ -1,4 +1,4 @@
-define(['./arrayEach', './baseMergeDeep', './getSymbols', '../lang/isArray', './isLength', '../lang/isObject', './isObjectLike', '../lang/isTypedArray', '../object/keys'], function(arrayEach, baseMergeDeep, getSymbols, isArray, isLength, isObject, isObjectLike, isTypedArray, keys) {
+define(['./arrayEach', './baseMergeDeep', './getSymbols', '../lang/isArray', './isArrayLike', '../lang/isObject', './isObjectLike', '../lang/isTypedArray', '../object/keys'], function(arrayEach, baseMergeDeep, getSymbols, isArray, isArrayLike, isObject, isObjectLike, isTypedArray, keys) {
 
   /** Used as a safe reference for `undefined` in pre-ES5 environments. */
   var undefined;
@@ -25,7 +25,7 @@ define(['./arrayEach', './baseMergeDeep', './getSymbols', '../lang/isArray', './
     if (!isObject(object)) {
       return object;
     }
-    var isSrcArr = isLength(source.length) && (isArray(source) || isTypedArray(source));
+    var isSrcArr = isArrayLike(source) && (isArray(source) || isTypedArray(source));
     if (!isSrcArr) {
       var props = keys(source);
       push.apply(props, getSymbols(source));

internal/baseMergeDeep.js

@@ -1,4 +1,4 @@
-define(['./arrayCopy', './getLength', '../lang/isArguments', '../lang/isArray', './isLength', '../lang/isPlainObject', '../lang/isTypedArray', '../lang/toPlainObject'], function(arrayCopy, getLength, isArguments, isArray, isLength, isPlainObject, isTypedArray, toPlainObject) {
+define(['./arrayCopy', '../lang/isArguments', '../lang/isArray', './isArrayLike', '../lang/isPlainObject', '../lang/isTypedArray', '../lang/toPlainObject'], function(arrayCopy, isArguments, isArray, isArrayLike, isPlainObject, isTypedArray, toPlainObject) {
 
   /** Used as a safe reference for `undefined` in pre-ES5 environments. */
   var undefined;
@@ -34,10 +34,10 @@ define(['./arrayCopy', './getLength', '../lang/isArguments', '../lang/isArray',
 
     if (isCommon) {
       result = srcValue;
-      if (isLength(srcValue.length) && (isArray(srcValue) || isTypedArray(srcValue))) {
+      if (isArrayLike(srcValue) && (isArray(srcValue) || isTypedArray(srcValue))) {
         result = isArray(value)
           ? value
-          : (getLength(value) ? arrayCopy(value) : []);
+          : (isArrayLike(value) ? arrayCopy(value) : []);
       }
       else if (isPlainObject(srcValue) || isArguments(srcValue)) {
         result = isArguments(value)

internal/basePullAt.js

@@ -16,7 +16,7 @@ define(['./isIndex'], function(isIndex) {
    * @returns {Array} Returns `array`.
    */
   function basePullAt(array, indexes) {
-    var length = indexes.length;
+    var length = array ? indexes.length : 0;
     while (length--) {
       var index = parseFloat(indexes[length]);
       if (index != previous && isIndex(index)) {

internal/binaryIndexBy.js

@@ -11,7 +11,7 @@ define([], function() {
 
   /** Used as references for the maximum length and index of an array. */
   var MAX_ARRAY_LENGTH = Math.pow(2, 32) - 1,
-      MAX_ARRAY_INDEX =  MAX_ARRAY_LENGTH - 1;
+      MAX_ARRAY_INDEX = MAX_ARRAY_LENGTH - 1;
 
   /**
    * This function is like `binaryIndex` except that it invokes `iteratee` for

internal/composeArgsRight.js

@@ -25,12 +25,12 @@ define([], function() {
     while (++argsIndex < argsLength) {
       result[argsIndex] = args[argsIndex];
     }
-    var pad = argsIndex;
+    var offset = argsIndex;
     while (++rightIndex < rightLength) {
-      result[pad + rightIndex] = partials[rightIndex];
+      result[offset + rightIndex] = partials[rightIndex];
     }
     while (++holdersIndex < holdersLength) {
-      result[pad + holders[holdersIndex]] = args[argsIndex++];
+      result[offset + holders[holdersIndex]] = args[argsIndex++];
     }
     return result;
   }

internal/createFind.js

@@ -19,7 +19,7 @@ define(['./baseCallback', './baseFind', './baseFindIndex', '../lang/isArray'], f
         return index > -1 ? collection[index] : undefined;
       }
       return baseFind(collection, predicate, eachFunc);
-    }
+    };
   }
 
   return createFind;

internal/createFlow.js

@@ -1,5 +1,11 @@
 define(['./LodashWrapper', './getData', './getFuncName', '../lang/isArray', './isLaziable'], function(LodashWrapper, getData, getFuncName, isArray, isLaziable) {
 
+  /** Used to compose bitmasks for wrapper metadata. */
+  var CURRY_FLAG = 8,
+      PARTIAL_FLAG = 32,
+      ARY_FLAG = 128,
+      REARG_FLAG = 256;
+
   /** Used as the `TypeError` message for "Functions" methods. */
   var FUNC_ERROR_TEXT = 'Expected a function';
 
@@ -35,7 +41,7 @@ define(['./LodashWrapper', './getData', './getFuncName', '../lang/isArray', './i
         funcName = getFuncName(func);
 
         var data = funcName == 'wrapper' ? getData(func) : null;
-        if (data && isLaziable(data[0])) {
+        if (data && isLaziable(data[0]) && data[1] == (ARY_FLAG | CURRY_FLAG | PARTIAL_FLAG | REARG_FLAG) && !data[4].length && data[9] == 1) {
           wrapper = wrapper[getFuncName(data[0])].apply(wrapper, data[3]);
         } else {
           wrapper = (func.length == 1 && isLaziable(func)) ? wrapper[funcName]() : wrapper.thru(func);

internal/createObjectMapper.js

@@ -0,0 +1,26 @@
+define(['./baseCallback', './baseForOwn'], function(baseCallback, baseForOwn) {
+
+  /**
+   * Creates a function for `_.mapKeys` or `_.mapValues`.
+   *
+   * @private
+   * @param {boolean} [isMapKeys] Specify mapping keys instead of values.
+   * @returns {Function} Returns the new map function.
+   */
+  function createObjectMapper(isMapKeys) {
+    return function(object, iteratee, thisArg) {
+      var result = {};
+      iteratee = baseCallback(iteratee, thisArg, 3);
+
+      baseForOwn(object, function(value, key, object) {
+        var mapped = iteratee(value, key, object);
+        key = isMapKeys ? mapped : key;
+        value = isMapKeys ? value : mapped;
+        result[key] = value;
+      });
+      return result;
+    };
+  }
+
+  return createObjectMapper;
+});

internal/createPadDir.js

@@ -10,7 +10,7 @@ define(['./baseToString', './createPadding'], function(baseToString, createPaddi
   function createPadDir(fromRight) {
     return function(string, length, chars) {
       string = baseToString(string);
-      return string && ((fromRight ? string : '') + createPadding(string, length, chars) + (fromRight ? '' : string));
+      return (fromRight ? string : '') + createPadding(string, length, chars) + (fromRight ? '' : string);
     };
   }
 

internal/equalByTag.js

@@ -36,8 +36,7 @@ define([], function() {
         // Treat `NaN` vs. `NaN` as equal.
         return (object != +object)
           ? other != +other
-          // But, treat `-0` vs. `+0` as not equal.
-          : (object == 0 ? ((1 / object) == (1 / other)) : object == +other);
+          : object == +other;
 
       case regexpTag:
       case stringTag:

internal/getLength.js

@@ -4,7 +4,7 @@ define(['./baseProperty'], function(baseProperty) {
    * Gets the "length" property value of `object`.
    *
    * **Note:** This function is used to avoid a [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792)
-   * in Safari on iOS 8.1 ARM64.
+   * that affects Safari on at least iOS 8.1-8.3 ARM64.
    *
    * @private
    * @param {Object} object The object to query.

internal/isArrayLike.js

@@ -0,0 +1,15 @@
+define(['./getLength', './isLength'], function(getLength, isLength) {
+
+  /**
+   * Checks if `value` is array-like.
+   *
+   * @private
+   * @param {*} value The value to check.
+   * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
+   */
+  function isArrayLike(value) {
+    return value != null && isLength(getLength(value));
+  }
+
+  return isArrayLike;
+});

internal/isIterateeCall.js

@@ -1,4 +1,4 @@
-define(['./getLength', './isIndex', './isLength', '../lang/isObject'], function(getLength, isIndex, isLength, isObject) {
+define(['./isArrayLike', './isIndex', '../lang/isObject'], function(isArrayLike, isIndex, isObject) {
 
   /**
    * Checks if the provided arguments are from an iteratee call.
@@ -14,13 +14,9 @@ define(['./getLength', './isIndex', './isLength', '../lang/isObject'], function(
       return false;
     }
     var type = typeof index;
-    if (type == 'number') {
-      var length = getLength(object),
-          prereq = isLength(length) && isIndex(index, length);
-    } else {
-      prereq = type == 'string' && index in object;
-    }
-    if (prereq) {
+    if (type == 'number'
+        ? (isArrayLike(object) && isIndex(index, object.length))
+        : (type == 'string' && index in object)) {
       var other = object[index];
       return value === value ? (value === other) : (other !== other);
     }

internal/isKey.js

@@ -1,7 +1,7 @@
 define(['../lang/isArray', './toObject'], function(isArray, toObject) {
 
   /** Used to match property names within property paths. */
-  var reIsDeepProp = /\.|\[(?:[^[\]]+|(["'])(?:(?!\1)[^\n\\]|\\.)*?)\1\]/,
+  var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\n\\]|\\.)*?\1)\]/,
       reIsPlainProp = /^\w*$/;
 
   /**

internal/isStrictComparable.js

@@ -9,7 +9,7 @@ define(['../lang/isObject'], function(isObject) {
    *  equality comparisons, else `false`.
    */
   function isStrictComparable(value) {
-    return value === value && (value === 0 ? ((1 / value) > 0) : !isObject(value));
+    return value === value && !isObject(value);
   }
 
   return isStrictComparable;

internal/pickByArray.js

@@ -1,7 +1,7 @@
 define(['./toObject'], function(toObject) {
 
   /**
-   * A specialized version of `_.pick` that picks `object` properties specified
+   * A specialized version of `_.pick` which picks `object` properties specified
    * by `props`.
    *
    * @private

internal/pickByCallback.js

@@ -1,7 +1,7 @@
 define(['./baseForIn'], function(baseForIn) {
 
   /**
-   * A specialized version of `_.pick` that picks `object` properties `predicate`
+   * A specialized version of `_.pick` which picks `object` properties `predicate`
    * returns truthy for.
    *
    * @private

internal/toIterable.js

@@ -1,4 +1,4 @@
-define(['./getLength', './isLength', '../lang/isObject', '../object/values'], function(getLength, isLength, isObject, values) {
+define(['./isArrayLike', '../lang/isObject', '../object/values'], function(isArrayLike, isObject, values) {
 
   /**
    * Converts `value` to an array-like object if it is not one.
@@ -11,7 +11,7 @@ define(['./getLength', './isLength', '../lang/isObject', '../object/values'], fu
     if (value == null) {
       return [];
     }
-    if (!isLength(getLength(value))) {
+    if (!isArrayLike(value)) {
       return values(value);
     }
     return isObject(value) ? value : Object(value);

lang/isArguments.js

@@ -1,7 +1,4 @@
-define(['../internal/isLength', '../internal/isObjectLike'], function(isLength, isObjectLike) {
-
-  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
-  var undefined;
+define(['../internal/isArrayLike', '../internal/isObjectLike'], function(isArrayLike, isObjectLike) {
 
   /** `Object#toString` result references. */
   var argsTag = '[object Arguments]';
@@ -32,8 +29,7 @@ define(['../internal/isLength', '../internal/isObjectLike'], function(isLength,
    * // => false
    */
   function isArguments(value) {
-    var length = isObjectLike(value) ? value.length : undefined;
-    return isLength(length) && objToString.call(value) == argsTag;
+    return isObjectLike(value) && isArrayLike(value) && objToString.call(value) == argsTag;
   }
 
   return isArguments;

lang/isEmpty.js

@@ -1,4 +1,4 @@
-define(['../internal/getLength', './isArguments', './isArray', './isFunction', '../internal/isLength', '../internal/isObjectLike', './isString', '../object/keys'], function(getLength, isArguments, isArray, isFunction, isLength, isObjectLike, isString, keys) {
+define(['./isArguments', './isArray', '../internal/isArrayLike', './isFunction', '../internal/isObjectLike', './isString', '../object/keys'], function(isArguments, isArray, isArrayLike, isFunction, isObjectLike, isString, keys) {
 
   /**
    * Checks if `value` is empty. A value is considered empty unless it is an
@@ -31,10 +31,9 @@ define(['../internal/getLength', './isArguments', './isArray', './isFunction', '
     if (value == null) {
       return true;
     }
-    var length = getLength(value);
-    if (isLength(length) && (isArray(value) || isString(value) || isArguments(value) ||
+    if (isArrayLike(value) && (isArray(value) || isString(value) || isArguments(value) ||
         (isObjectLike(value) && isFunction(value.splice)))) {
-      return !length;
+      return !value.length;
     }
     return !keys(value).length;
   }

lang/isRegExp.js

@@ -29,7 +29,7 @@ define(['../internal/isObjectLike'], function(isObjectLike) {
    * // => false
    */
   function isRegExp(value) {
-    return (isObjectLike(value) && objToString.call(value) == regexpTag) || false;
+    return isObjectLike(value) && objToString.call(value) == regexpTag;
   }
 
   return isRegExp;

main.js

@@ -1,6 +1,6 @@
 /**
  * @license
- * lodash 3.7.0 (Custom Build) <https://lodash.com/>
+ * lodash 3.8.0 (Custom Build) <https://lodash.com/>
  * Build: `lodash modern exports="amd" -d -o ./main.js`
  * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
  * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
@@ -13,7 +13,7 @@
   var undefined;
 
   /** Used as the semantic version number. */
-  var VERSION = '3.7.0';
+  var VERSION = '3.8.0';
 
   /** Used to compose bitmasks for wrapper metadata. */
   var BIND_FLAG = 1,
@@ -88,7 +88,7 @@
       reInterpolate = /<%=([\s\S]+?)%>/g;
 
   /** Used to match property names within property paths. */
-  var reIsDeepProp = /\.|\[(?:[^[\]]+|(["'])(?:(?!\1)[^\n\\]|\\.)*?)\1\]/,
+  var reIsDeepProp = /\.|\[(?:[^[\]]*|(["'])(?:(?!\1)[^\n\\]|\\.)*?\1)\]/,
       reIsPlainProp = /^\w*$/,
       rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\n\\]|\\.)*?)\2)\]/g;
 
@@ -277,8 +277,6 @@
    */
   var root = freeGlobal || ((freeWindow !== (this && this.window)) && freeWindow) || freeSelf || this;
 
-  /*--------------------------------------------------------------------------*/
-
   /**
    * The base implementation of `compareAscending` which compares values and
    * sorts them in ascending order without guaranteeing a stable sort.
@@ -649,8 +647,6 @@
     return htmlUnescapes[chr];
   }
 
-  /*--------------------------------------------------------------------------*/
-
   /**
    * Create a new pristine `lodash` function using the given `context` object.
    *
@@ -746,7 +742,7 @@
         getOwnPropertySymbols = isNative(getOwnPropertySymbols = Object.getOwnPropertySymbols) && getOwnPropertySymbols,
         getPrototypeOf = isNative(getPrototypeOf = Object.getPrototypeOf) && getPrototypeOf,
         push = arrayProto.push,
-        preventExtensions = isNative(Object.preventExtensions = Object.preventExtensions) && preventExtensions,
+        preventExtensions = isNative(preventExtensions = Object.preventExtensions) && preventExtensions,
         propertyIsEnumerable = objectProto.propertyIsEnumerable,
         Set = isNative(Set = context.Set) && Set,
         setTimeout = context.setTimeout,
@@ -774,12 +770,19 @@
       //
       // 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;
+      // to assign values to readonly indexes of strings.
+      var func = preventExtensions && isNative(func = Object.assign) && func;
+      try {
+        if (func) {
+          var object = preventExtensions({ '1': 0 });
+          object[0] = 1;
+        }
+      } catch(e) {
+        // Only attempt in strict mode.
+        try { func(object, 'xo'); } catch(e) {}
+        return !object[1] && func;
+      }
+      return false;
     }());
 
     /* Native method references for those with the same name as other `lodash` methods. */
@@ -800,7 +803,7 @@
 
     /** Used as references for the maximum length and index of an array. */
     var MAX_ARRAY_LENGTH = Math.pow(2, 32) - 1,
-        MAX_ARRAY_INDEX =  MAX_ARRAY_LENGTH - 1,
+        MAX_ARRAY_INDEX = MAX_ARRAY_LENGTH - 1,
         HALF_MAX_ARRAY_LENGTH = MAX_ARRAY_LENGTH >>> 1;
 
     /** Used as the size, in bytes, of each `Float64Array` element. */
@@ -818,8 +821,6 @@
     /** Used to lookup unminified function names. */
     var realNames = {};
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates a `lodash` object which wraps `value` to enable implicit chaining.
      * Methods that operate on and return arrays, collections, and functions can
@@ -959,6 +960,7 @@
 
     (function(x) {
       var Ctor = function() { this.x = x; },
+          args = arguments,
           object = { '0': x, 'length': x },
           props = [];
 
@@ -1008,7 +1010,7 @@
        * @type boolean
        */
       try {
-        support.nonEnumArgs = !propertyIsEnumerable.call(arguments, 1);
+        support.nonEnumArgs = !propertyIsEnumerable.call(args, 1);
       } catch(e) {
         support.nonEnumArgs = true;
       }
@@ -1075,8 +1077,6 @@
       }
     };
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates a lazy wrapper object which wraps `value` to enable lazy evaluation.
      *
@@ -1205,8 +1205,6 @@
       return result;
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates a cache object to store key/value pairs.
      *
@@ -1275,8 +1273,6 @@
       return this;
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      *
      * Creates a cache object to store unique values.
@@ -1326,8 +1322,6 @@
       }
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Copies the values of `source` to `array`.
      *
@@ -1671,8 +1665,9 @@
      */
     function baseAt(collection, props) {
       var index = -1,
-          length = collection.length,
-          isArr = isLength(length),
+          isNil = collection == null,
+          isArr = !isNil && isArrayLike(collection),
+          length = isArr && collection.length,
           propsLength = props.length,
           result = Array(propsLength);
 
@@ -1681,7 +1676,7 @@
         if (isArr) {
           result[index] = isIndex(key, length) ? collection[key] : undefined;
         } else {
-          result[index] = collection[key];
+          result[index] = isNil ? undefined : collection[key];
         }
       }
       return result;
@@ -2008,8 +2003,8 @@
      *
      * @private
      * @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 {boolean} [isDeep] Specify a deep flatten.
+     * @param {boolean} [isStrict] Restrict flattening to arrays-like objects.
      * @returns {Array} Returns the new flattened array.
      */
     function baseFlatten(array, isDeep, isStrict) {
@@ -2020,8 +2015,8 @@
 
       while (++index < length) {
         var value = array[index];
-
-        if (isObjectLike(value) && isLength(value.length) && (isArray(value) || isArguments(value))) {
+        if (isObjectLike(value) && isArrayLike(value) &&
+            (isStrict || isArray(value) || isArguments(value))) {
           if (isDeep) {
             // Recursively flatten arrays (susceptible to call stack limits).
             value = baseFlatten(value, isDeep, isStrict);
@@ -2029,7 +2024,6 @@
           var valIndex = -1,
               valLength = value.length;
 
-          result.length += valLength;
           while (++valIndex < valLength) {
             result[++resIndex] = value[valIndex];
           }
@@ -2150,9 +2144,9 @@
           length = path.length;
 
       while (object != null && ++index < length) {
-        var result = object = object[path[index]];
+        object = object[path[index]];
       }
-      return result;
+      return (index && index == length) ? object : undefined;
     }
 
     /**
@@ -2171,8 +2165,7 @@
     function baseIsEqual(value, other, customizer, isLoose, stackA, stackB) {
       // Exit early for identical values.
       if (value === other) {
-        // Treat `+0` vs. `-0` as not equal.
-        return value !== 0 || (1 / value == 1 / other);
+        return true;
       }
       var valType = typeof value,
           othType = typeof other;
@@ -2321,8 +2314,7 @@
      */
     function baseMap(collection, iteratee) {
       var index = -1,
-          length = getLength(collection),
-          result = isLength(length) ? Array(length) : [];
+          result = isArrayLike(collection) ? Array(collection.length) : [];
 
       baseEach(collection, function(value, key, collection) {
         result[++index] = iteratee(value, key, collection);
@@ -2421,7 +2413,7 @@
       if (!isObject(object)) {
         return object;
       }
-      var isSrcArr = isLength(source.length) && (isArray(source) || isTypedArray(source));
+      var isSrcArr = isArrayLike(source) && (isArray(source) || isTypedArray(source));
       if (!isSrcArr) {
         var props = keys(source);
         push.apply(props, getSymbols(source));
@@ -2484,10 +2476,10 @@
 
       if (isCommon) {
         result = srcValue;
-        if (isLength(srcValue.length) && (isArray(srcValue) || isTypedArray(srcValue))) {
+        if (isArrayLike(srcValue) && (isArray(srcValue) || isTypedArray(srcValue))) {
           result = isArray(value)
             ? value
-            : (getLength(value) ? arrayCopy(value) : []);
+            : (isArrayLike(value) ? arrayCopy(value) : []);
         }
         else if (isPlainObject(srcValue) || isArguments(srcValue)) {
           result = isArguments(value)
@@ -2549,7 +2541,7 @@
      * @returns {Array} Returns `array`.
      */
     function basePullAt(array, indexes) {
-      var length = indexes.length;
+      var length = array ? indexes.length : 0;
       while (length--) {
         var index = parseFloat(indexes[length]);
         if (index != previous && isIndex(index)) {
@@ -3035,12 +3027,12 @@
       while (++argsIndex < argsLength) {
         result[argsIndex] = args[argsIndex];
       }
-      var pad = argsIndex;
+      var offset = argsIndex;
       while (++rightIndex < rightLength) {
-        result[pad + rightIndex] = partials[rightIndex];
+        result[offset + rightIndex] = partials[rightIndex];
       }
       while (++holdersIndex < holdersLength) {
-        result[pad + holders[holdersIndex]] = args[argsIndex++];
+        result[offset + holders[holdersIndex]] = args[argsIndex++];
       }
       return result;
     }
@@ -3308,7 +3300,7 @@
           return index > -1 ? collection[index] : undefined;
         }
         return baseFind(collection, predicate, eachFunc);
-      }
+      };
     }
 
     /**
@@ -3374,7 +3366,7 @@
           funcName = getFuncName(func);
 
           var data = funcName == 'wrapper' ? getData(func) : null;
-          if (data && isLaziable(data[0])) {
+          if (data && isLaziable(data[0]) && data[1] == (ARY_FLAG | CURRY_FLAG | PARTIAL_FLAG | REARG_FLAG) && !data[4].length && data[9] == 1) {
             wrapper = wrapper[getFuncName(data[0])].apply(wrapper, data[3]);
           } else {
             wrapper = (func.length == 1 && isLaziable(func)) ? wrapper[funcName]() : wrapper.thru(func);
@@ -3444,6 +3436,28 @@
       };
     }
 
+    /**
+     * Creates a function for `_.mapKeys` or `_.mapValues`.
+     *
+     * @private
+     * @param {boolean} [isMapKeys] Specify mapping keys instead of values.
+     * @returns {Function} Returns the new map function.
+     */
+    function createObjectMapper(isMapKeys) {
+      return function(object, iteratee, thisArg) {
+        var result = {};
+        iteratee = getCallback(iteratee, thisArg, 3);
+
+        baseForOwn(object, function(value, key, object) {
+          var mapped = iteratee(value, key, object);
+          key = isMapKeys ? mapped : key;
+          value = isMapKeys ? value : mapped;
+          result[key] = value;
+        });
+        return result;
+      };
+    }
+
     /**
      * Creates a function for `_.padLeft` or `_.padRight`.
      *
@@ -3454,7 +3468,7 @@
     function createPadDir(fromRight) {
       return function(string, length, chars) {
         string = baseToString(string);
-        return string && ((fromRight ? string : '') + createPadding(string, length, chars) + (fromRight ? '' : string));
+        return (fromRight ? string : '') + createPadding(string, length, chars) + (fromRight ? '' : string);
       };
     }
 
@@ -3800,8 +3814,7 @@
           // Treat `NaN` vs. `NaN` as equal.
           return (object != +object)
             ? other != +other
-            // But, treat `-0` vs. `+0` as not equal.
-            : (object == 0 ? ((1 / object) == (1 / other)) : object == +other);
+            : object == +other;
 
         case regexpTag:
         case stringTag:
@@ -3981,7 +3994,7 @@
      * Gets the "length" property value of `object`.
      *
      * **Note:** This function is used to avoid a [JIT bug](https://bugs.webkit.org/show_bug.cgi?id=142792)
-     * in Safari on iOS 8.1 ARM64.
+     * that affects Safari on at least iOS 8.1-8.3 ARM64.
      *
      * @private
      * @param {Object} object The object to query.
@@ -4120,6 +4133,17 @@
       return func == null ? undefined : func.apply(object, args);
     }
 
+    /**
+     * Checks if `value` is array-like.
+     *
+     * @private
+     * @param {*} value The value to check.
+     * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
+     */
+    function isArrayLike(value) {
+      return value != null && isLength(getLength(value));
+    }
+
     /**
      * Checks if `value` is a valid array-like index.
      *
@@ -4148,13 +4172,9 @@
         return false;
       }
       var type = typeof index;
-      if (type == 'number') {
-        var length = getLength(object),
-            prereq = isLength(length) && isIndex(index, length);
-      } else {
-        prereq = type == 'string' && index in object;
-      }
-      if (prereq) {
+      if (type == 'number'
+          ? (isArrayLike(object) && isIndex(index, object.length))
+          : (type == 'string' && index in object)) {
         var other = object[index];
         return value === value ? (value === other) : (other !== other);
       }
@@ -4215,7 +4235,7 @@
      *  equality comparisons, else `false`.
      */
     function isStrictComparable(value) {
-      return value === value && (value === 0 ? ((1 / value) > 0) : !isObject(value));
+      return value === value && !isObject(value);
     }
 
     /**
@@ -4289,7 +4309,7 @@
     }
 
     /**
-     * A specialized version of `_.pick` that picks `object` properties specified
+     * A specialized version of `_.pick` which picks `object` properties specified
      * by `props`.
      *
      * @private
@@ -4314,7 +4334,7 @@
     }
 
     /**
-     * A specialized version of `_.pick` that picks `object` properties `predicate`
+     * A specialized version of `_.pick` which picks `object` properties `predicate`
      * returns truthy for.
      *
      * @private
@@ -4459,7 +4479,7 @@
       if (value == null) {
         return [];
       }
-      if (!isLength(getLength(value))) {
+      if (!isArrayLike(value)) {
         return values(value);
       }
       return isObject(value) ? value : Object(value);
@@ -4507,8 +4527,6 @@
         : new LodashWrapper(wrapper.__wrapped__, wrapper.__chain__, arrayCopy(wrapper.__actions__));
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates an array of elements split into groups the length of `size`.
      * If `collection` can't be split evenly, the final chunk will be the remaining
@@ -4577,11 +4595,8 @@
 
     /**
      * Creates an array excluding all values of the provided arrays using
-     * `SameValueZero` for equality comparisons.
-     *
-     * **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`.
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons.
      *
      * @static
      * @memberOf _
@@ -4595,7 +4610,7 @@
      * // => [1, 3]
      */
     var difference = restParam(function(array, values) {
-      return (isArray(array) || isArguments(array))
+      return isArrayLike(array)
         ? baseDifference(array, baseFlatten(values, false, true))
         : [];
     });
@@ -4990,13 +5005,10 @@
 
     /**
      * Gets the index at which the first occurrence of `value` is found in `array`
-     * using `SameValueZero` for equality comparisons. If `fromIndex` is negative,
-     * 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`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
-     * comparisons are like strict equality comparisons, e.g. `===`, except that
-     * `NaN` matches `NaN`.
+     * using [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons. If `fromIndex` is negative, it is used as the offset
+     * from the end of `array`. If `array` is sorted providing `true` for `fromIndex`
+     * performs a faster binary search.
      *
      * @static
      * @memberOf _
@@ -5056,13 +5068,10 @@
     }
 
     /**
-     * Creates an array of unique values in all provided arrays using `SameValueZero`
+     * Creates an array of unique values in all provided arrays using
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
      * for equality comparisons.
      *
-     * **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 _
      * @category Array
@@ -5083,7 +5092,7 @@
 
       while (++argsIndex < argsLength) {
         var value = arguments[argsIndex];
-        if (isArray(value) || isArguments(value)) {
+        if (isArrayLike(value)) {
           args.push(value);
           caches.push((isCommon && value.length >= 120) ? createCache(argsIndex && value) : null);
         }
@@ -5188,14 +5197,11 @@
     }
 
     /**
-     * Removes all provided values from `array` using `SameValueZero` for equality
-     * comparisons.
+     * Removes all provided values from `array` using
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons.
      *
-     * **Notes:**
-     *  - 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`
+     * **Note:** Unlike `_.without`, this method mutates `array`.
      *
      * @static
      * @memberOf _
@@ -5259,7 +5265,6 @@
      * // => [10, 20]
      */
     var pullAt = restParam(function(array, indexes) {
-      array || (array = []);
       indexes = baseFlatten(indexes);
 
       var result = baseAt(array, indexes);
@@ -5626,11 +5631,8 @@
 
     /**
      * Creates an array of unique values, in order, of the provided arrays using
-     * `SameValueZero` for equality comparisons.
-     *
-     * **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`.
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons.
      *
      * @static
      * @memberOf _
@@ -5647,8 +5649,9 @@
     });
 
     /**
-     * Creates a duplicate-free version of an array, using `SameValueZero` for
-     * equality comparisons, in which only the first occurence of each element
+     * Creates a duplicate-free version of an array, using
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-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
@@ -5666,10 +5669,6 @@
      * callback returns `true` for elements that have the properties of the given
      * object, else `false`.
      *
-     * **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 _
      * @alias unique
@@ -5719,7 +5718,7 @@
 
     /**
      * This method is like `_.zip` except that it accepts an array of grouped
-     * elements and creates an array regrouping the elements to their pre-`_.zip`
+     * elements and creates an array regrouping the elements to their pre-zip
      * configuration.
      *
      * @static
@@ -5736,10 +5735,19 @@
      * // => [['fred', 'barney'], [30, 40], [true, false]]
      */
     function unzip(array) {
+      if (!(array && array.length)) {
+        return [];
+      }
       var index = -1,
-          length = (array && array.length && arrayMax(arrayMap(array, getLength))) >>> 0,
-          result = Array(length);
+          length = 0;
 
+      array = arrayFilter(array, function(group) {
+        if (isArrayLike(group)) {
+          length = nativeMax(group.length, length);
+          return true;
+        }
+      });
+      var result = Array(length);
       while (++index < length) {
         result[index] = arrayMap(array, baseProperty(index));
       }
@@ -5747,12 +5755,44 @@
     }
 
     /**
-     * Creates an array excluding all provided values using `SameValueZero` for
-     * equality comparisons.
+     * This method is like `_.unzip` except that it accepts an iteratee to specify
+     * how regrouped values should be combined. The `iteratee` is bound to `thisArg`
+     * and invoked with four arguments: (accumulator, value, index, group).
      *
-     * **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 _
+     * @category Array
+     * @param {Array} array The array of grouped elements to process.
+     * @param {Function} [iteratee] The function to combine regrouped values.
+     * @param {*} [thisArg] The `this` binding of `iteratee`.
+     * @returns {Array} Returns the new array of regrouped elements.
+     * @example
+     *
+     * var zipped = _.zip([1, 2], [10, 20], [100, 200]);
+     * // => [[1, 10, 100], [2, 20, 200]]
+     *
+     * _.unzipWith(zipped, _.add);
+     * // => [3, 30, 300]
+     */
+    function unzipWith(array, iteratee, thisArg) {
+      var length = array ? array.length : 0;
+      if (!length) {
+        return [];
+      }
+      var result = unzip(array);
+      if (iteratee == null) {
+        return result;
+      }
+      iteratee = bindCallback(iteratee, thisArg, 4);
+      return arrayMap(result, function(group) {
+        return arrayReduce(group, iteratee, undefined, true);
+      });
+    }
+
+    /**
+     * Creates an array excluding all provided values using
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons.
      *
      * @static
      * @memberOf _
@@ -5766,7 +5806,7 @@
      * // => [3]
      */
     var without = restParam(function(array, values) {
-      return (isArray(array) || isArguments(array))
+      return isArrayLike(array)
         ? baseDifference(array, values)
         : [];
     });
@@ -5791,7 +5831,7 @@
 
       while (++index < length) {
         var array = arguments[index];
-        if (isArray(array) || isArguments(array)) {
+        if (isArrayLike(array)) {
           var result = result
             ? baseDifference(result, array).concat(baseDifference(array, result))
             : array;
@@ -5857,7 +5897,37 @@
       return result;
     }
 
-    /*------------------------------------------------------------------------*/
+    /**
+     * This method is like `_.zip` except that it accepts an iteratee to specify
+     * how grouped values should be combined. The `iteratee` is bound to `thisArg`
+     * and invoked with four arguments: (accumulator, value, index, group).
+     *
+     * @static
+     * @memberOf _
+     * @category Array
+     * @param {...Array} [arrays] The arrays to process.
+     * @param {Function} [iteratee] The function to combine grouped values.
+     * @param {*} [thisArg] The `this` binding of `iteratee`.
+     * @returns {Array} Returns the new array of grouped elements.
+     * @example
+     *
+     * _.zipWith([1, 2], [10, 20], [100, 200], _.add);
+     * // => [111, 222]
+     */
+    var zipWith = restParam(function(arrays) {
+      var length = arrays.length,
+          iteratee = arrays[length - 2],
+          thisArg = arrays[length - 1];
+
+      if (length > 2 && typeof iteratee == 'function') {
+        length -= 2;
+      } else {
+        iteratee = (length > 1 && typeof thisArg == 'function') ? (--length, thisArg) : undefined;
+        thisArg = undefined;
+      }
+      arrays.length = length;
+      return unzipWith(arrays, iteratee, thisArg);
+    });
 
     /**
      * Creates a `lodash` object that wraps `value` with explicit method
@@ -6109,8 +6179,6 @@
       return baseWrapperValue(this.__wrapped__, this.__actions__);
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates an array of elements corresponding to the given keys, or indexes,
      * of `collection`. Keys may be specified as individual arguments or as arrays
@@ -6132,10 +6200,6 @@
      * // => ['barney', 'pebbles']
      */
     var at = restParam(function(collection, props) {
-      var length = collection ? getLength(collection) : 0;
-      if (isLength(length)) {
-        collection = toIterable(collection);
-      }
       return baseAt(collection, baseFlatten(props));
     });
 
@@ -6508,13 +6572,10 @@
     });
 
     /**
-     * Checks if `value` is in `collection` using `SameValueZero` for equality
-     * comparisons. If `fromIndex` is negative, it is used as the offset from
-     * the end of `collection`.
-     *
-     * **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`.
+     * Checks if `value` is in `collection` using
+     * [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero)
+     * for equality comparisons. If `fromIndex` is negative, it is used as the offset
+     * from the end of `collection`.
      *
      * @static
      * @memberOf _
@@ -6634,8 +6695,7 @@
       var index = -1,
           isFunc = typeof path == 'function',
           isProp = isKey(path),
-          length = getLength(collection),
-          result = isLength(length) ? Array(length) : [];
+          result = isArrayLike(collection) ? Array(collection.length) : [];
 
       baseEach(collection, function(value) {
         var func = isFunc ? path : (isProp && value != null && value[path]);
@@ -6664,10 +6724,11 @@
      * `_.every`, `_.filter`, `_.map`, `_.mapValues`, `_.reject`, and `_.some`.
      *
      * The guarded methods are:
-     * `ary`, `callback`, `chunk`, `clone`, `create`, `curry`, `curryRight`, `drop`,
-     * `dropRight`, `every`, `fill`, `flatten`, `invert`, `max`, `min`, `parseInt`,
-     * `slice`, `sortBy`, `take`, `takeRight`, `template`, `trim`, `trimLeft`,
-     * `trimRight`, `trunc`, `random`, `range`, `sample`, `some`, `uniq`, and `words`
+     * `ary`, `callback`, `chunk`, `clone`, `create`, `curry`, `curryRight`,
+     * `drop`, `dropRight`, `every`, `fill`, `flatten`, `invert`, `max`, `min`,
+     * `parseInt`, `slice`, `sortBy`, `take`, `takeRight`, `template`, `trim`,
+     * `trimLeft`, `trimRight`, `trunc`, `random`, `range`, `sample`, `some`,
+     * `sum`, `uniq`, and `words`
      *
      * @static
      * @memberOf _
@@ -6855,23 +6916,12 @@
      * }, []);
      * // => [4, 5, 2, 3, 0, 1]
      */
-    var reduceRight =  createReduce(arrayReduceRight, baseEachRight);
+    var reduceRight = createReduce(arrayReduceRight, baseEachRight);
 
     /**
      * The opposite of `_.filter`; this method returns the elements of `collection`
      * that `predicate` does **not** return truthy for.
      *
-     * If a property name is provided for `predicate` 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
-     * callback returns `true` for elements that have the properties of the given
-     * object, else `false`.
-     *
      * @static
      * @memberOf _
      * @category Collection
@@ -7250,8 +7300,6 @@
       return filter(collection, baseMatches(source));
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Gets the number of milliseconds that have elapsed since the Unix epoch
      * (1 January 1970 00:00:00 UTC).
@@ -7270,8 +7318,6 @@
       return new Date().getTime();
     };
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * The opposite of `_.before`; this method creates a function that invokes
      * `func` once it is called `n` or more times.
@@ -8251,8 +8297,6 @@
       return createWrapper(wrapper, PARTIAL_FLAG, null, [value], []);
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Creates a clone of `value`. If `isDeep` is `true` nested objects are cloned,
      * otherwise they are assigned by reference. If `customizer` is provided it is
@@ -8384,8 +8428,7 @@
      * // => false
      */
     function isArguments(value) {
-      var length = isObjectLike(value) ? value.length : undefined;
-      return isLength(length) && objToString.call(value) == argsTag;
+      return isObjectLike(value) && isArrayLike(value) && objToString.call(value) == argsTag;
     }
 
     /**
@@ -8506,10 +8549,9 @@
       if (value == null) {
         return true;
       }
-      var length = getLength(value);
-      if (isLength(length) && (isArray(value) || isString(value) || isArguments(value) ||
+      if (isArrayLike(value) && (isArray(value) || isString(value) || isArguments(value) ||
           (isObjectLike(value) && isFunction(value.splice)))) {
-        return !length;
+        return !value.length;
       }
       return !keys(value).length;
     }
@@ -8899,7 +8941,7 @@
      * // => false
      */
     function isRegExp(value) {
-      return (isObjectLike(value) && objToString.call(value) == regexpTag) || false;
+      return isObjectLike(value) && objToString.call(value) == regexpTag;
     }
 
     /**
@@ -9015,8 +9057,6 @@
       return baseCopy(value, keysIn(value));
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Assigns own enumerable properties of source object(s) to the destination
      * object. Subsequent sources overwrite property assignments of previous sources.
@@ -9027,7 +9067,6 @@
      * **Note:** This method mutates `object` and is based on
      * [`Object.assign`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.assign).
      *
-     *
      * @static
      * @memberOf _
      * @alias extend
@@ -9499,12 +9538,9 @@
      * // => ['0', '1']
      */
     var keys = !nativeKeys ? shimKeys : function(object) {
-      if (object) {
-        var Ctor = object.constructor,
-            length = object.length;
-      }
+      var Ctor = object != null && object.constructor;
       if ((typeof Ctor == 'function' && Ctor.prototype === object) ||
-          (typeof object != 'function' && isLength(length))) {
+          (typeof object != 'function' && isArrayLike(object))) {
         return shimKeys(object);
       }
       return isObject(object) ? nativeKeys(object) : [];
@@ -9561,6 +9597,28 @@
       return result;
     }
 
+    /**
+     * The opposite of `_.mapValues`; this method creates an object with the
+     * same values as `object` and keys generated by running each own enumerable
+     * property of `object` through `iteratee`.
+     *
+     * @static
+     * @memberOf _
+     * @category Object
+     * @param {Object} object The object to iterate over.
+     * @param {Function|Object|string} [iteratee=_.identity] The function invoked
+     *  per iteration.
+     * @param {*} [thisArg] The `this` binding of `iteratee`.
+     * @returns {Object} Returns the new mapped object.
+     * @example
+     *
+     * _.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
+     *   return key + value;
+     * });
+     * // => { 'a1': 1, 'b2': 2 }
+     */
+    var mapKeys = createObjectMapper(true);
+
     /**
      * Creates an object with the same keys as `object` and values generated by
      * running each own enumerable property of `object` through `iteratee`. The
@@ -9602,15 +9660,7 @@
      * _.mapValues(users, 'age');
      * // => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
      */
-    function mapValues(object, iteratee, thisArg) {
-      var result = {};
-      iteratee = getCallback(iteratee, thisArg, 3);
-
-      baseForOwn(object, function(value, key, object) {
-        result[key] = iteratee(value, key, object);
-      });
-      return result;
-    }
+    var mapValues = createObjectMapper();
 
     /**
      * Recursively merges own enumerable properties of the source object(s), that
@@ -9665,11 +9715,6 @@
     /**
      * The opposite of `_.pick`; this method creates an object composed of the
      * own and inherited enumerable properties of `object` that are not omitted.
-     * Property names may be specified as individual arguments or as arrays of
-     * property names. If `predicate` is provided it is invoked for each property
-     * of `object` omitting the properties `predicate` returns truthy for. The
-     * predicate is bound to `thisArg` and invoked with three arguments:
-     * (value, key, object).
      *
      * @static
      * @memberOf _
@@ -9963,8 +10008,6 @@
       return baseValues(object, keysIn(object));
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Checks if `n` is between `start` and up to but not including, `end`. If
      * `end` is not specified it is set to `start` with `start` then set to `0`.
@@ -10069,8 +10112,6 @@
       return baseRandom(min, max);
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Converts `string` to [camel case](https://en.wikipedia.org/wiki/CamelCase).
      *
@@ -10936,8 +10977,6 @@
       return string.match(pattern || reWords) || [];
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Attempts to invoke `func`, returning either the result or the caught error
      * object. Any additional arguments are provided to `func` when it is invoked.
@@ -11008,7 +11047,9 @@
       if (guard && isIterateeCall(func, thisArg, guard)) {
         thisArg = null;
       }
-      return baseCallback(func, thisArg);
+      return isObjectLike(func)
+        ? matches(func)
+        : baseCallback(func, thisArg);
     }
 
     /**
@@ -11133,7 +11174,7 @@
     var method = restParam(function(path, args) {
       return function(object) {
         return invokePath(object, path, args);
-      }
+      };
     });
 
     /**
@@ -11470,8 +11511,6 @@
       return baseToString(prefix) + id;
     }
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * Adds two numbers.
      *
@@ -11636,8 +11675,6 @@
         : baseSum(collection, iteratee);
     }
 
-    /*------------------------------------------------------------------------*/
-
     // Ensure wrappers are instances of `baseLodash`.
     lodash.prototype = baseLodash.prototype;
 
@@ -11708,6 +11745,7 @@
     lodash.keys = keys;
     lodash.keysIn = keysIn;
     lodash.map = map;
+    lodash.mapKeys = mapKeys;
     lodash.mapValues = mapValues;
     lodash.matches = matches;
     lodash.matchesProperty = matchesProperty;
@@ -11756,6 +11794,7 @@
     lodash.union = union;
     lodash.uniq = uniq;
     lodash.unzip = unzip;
+    lodash.unzipWith = unzipWith;
     lodash.values = values;
     lodash.valuesIn = valuesIn;
     lodash.where = where;
@@ -11764,6 +11803,7 @@
     lodash.xor = xor;
     lodash.zip = zip;
     lodash.zipObject = zipObject;
+    lodash.zipWith = zipWith;
 
     // Add aliases.
     lodash.backflow = flowRight;
@@ -11782,8 +11822,6 @@
     // Add functions to `lodash.prototype`.
     mixin(lodash, lodash);
 
-    /*------------------------------------------------------------------------*/
-
     // Add functions that return unwrapped values when chaining.
     lodash.add = add;
     lodash.attempt = attempt;
@@ -11887,8 +11925,6 @@
       return source;
     }()), false);
 
-    /*------------------------------------------------------------------------*/
-
     // Add functions capable of returning wrapped and unwrapped values when chaining.
     lodash.sample = sample;
 
@@ -11901,8 +11937,6 @@
       });
     };
 
-    /*------------------------------------------------------------------------*/
-
     /**
      * The semantic version number.
      *
@@ -12013,8 +12047,13 @@
 
     LazyWrapper.prototype.slice = function(start, end) {
       start = start == null ? 0 : (+start || 0);
-      var result = start < 0 ? this.takeRight(-start) : this.drop(start);
 
+      var result = this;
+      if (start < 0) {
+        result = this.takeRight(-start);
+      } else if (start) {
+        result = this.drop(start);
+      }
       if (end !== undefined) {
         end = (+end || 0);
         result = end < 0 ? result.dropRight(-end) : result.take(end - start);
@@ -12037,7 +12076,6 @@
 
       lodash.prototype[methodName] = function() {
         var args = arguments,
-            length = args.length,
             chainAll = this.__chain__,
             value = this.__wrapped__,
             isHybrid = !!this.__actions__.length,
@@ -12126,8 +12164,6 @@
     return lodash;
   }
 
-  /*--------------------------------------------------------------------------*/
-
   // Export lodash.
   var _ = runInContext();
 

object.js

@@ -1,4 +1,4 @@
-define(['./object/assign', './object/create', './object/defaults', './object/extend', './object/findKey', './object/findLastKey', './object/forIn', './object/forInRight', './object/forOwn', './object/forOwnRight', './object/functions', './object/get', './object/has', './object/invert', './object/keys', './object/keysIn', './object/mapValues', './object/merge', './object/methods', './object/omit', './object/pairs', './object/pick', './object/result', './object/set', './object/transform', './object/values', './object/valuesIn'], function(assign, create, defaults, extend, findKey, findLastKey, forIn, forInRight, forOwn, forOwnRight, functions, get, has, invert, keys, keysIn, mapValues, merge, methods, omit, pairs, pick, result, set, transform, values, valuesIn) {
+define(['./object/assign', './object/create', './object/defaults', './object/extend', './object/findKey', './object/findLastKey', './object/forIn', './object/forInRight', './object/forOwn', './object/forOwnRight', './object/functions', './object/get', './object/has', './object/invert', './object/keys', './object/keysIn', './object/mapKeys', './object/mapValues', './object/merge', './object/methods', './object/omit', './object/pairs', './object/pick', './object/result', './object/set', './object/transform', './object/values', './object/valuesIn'], function(assign, create, defaults, extend, findKey, findLastKey, forIn, forInRight, forOwn, forOwnRight, functions, get, has, invert, keys, keysIn, mapKeys, mapValues, merge, methods, omit, pairs, pick, result, set, transform, values, valuesIn) {
   return {
     'assign': assign,
     'create': create,
@@ -16,6 +16,7 @@ define(['./object/assign', './object/create', './object/defaults', './object/ext
     'invert': invert,
     'keys': keys,
     'keysIn': keysIn,
+    'mapKeys': mapKeys,
     'mapValues': mapValues,
     'merge': merge,
     'methods': methods,

object/assign.js

@@ -10,7 +10,6 @@ define(['../internal/assignWith', '../internal/baseAssign', '../internal/createA
    * **Note:** This method mutates `object` and is based on
    * [`Object.assign`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.assign).
    *
-   *
    * @static
    * @memberOf _
    * @alias extend

object/keys.js

@@ -1,4 +1,4 @@
-define(['../internal/isLength', '../lang/isNative', '../lang/isObject', '../internal/shimKeys'], function(isLength, isNative, isObject, shimKeys) {
+define(['../internal/isArrayLike', '../lang/isNative', '../lang/isObject', '../internal/shimKeys'], function(isArrayLike, isNative, isObject, shimKeys) {
 
   /* Native method references for those with the same name as other `lodash` methods. */
   var nativeKeys = isNative(nativeKeys = Object.keys) && nativeKeys;
@@ -31,12 +31,9 @@ define(['../internal/isLength', '../lang/isNative', '../lang/isObject', '../inte
    * // => ['0', '1']
    */
   var keys = !nativeKeys ? shimKeys : function(object) {
-    if (object) {
-      var Ctor = object.constructor,
-          length = object.length;
-    }
+    var Ctor = object != null && object.constructor;
     if ((typeof Ctor == 'function' && Ctor.prototype === object) ||
-        (typeof object != 'function' && isLength(length))) {
+        (typeof object != 'function' && isArrayLike(object))) {
       return shimKeys(object);
     }
     return isObject(object) ? nativeKeys(object) : [];

object/mapKeys.js

@@ -0,0 +1,26 @@
+define(['../internal/createObjectMapper'], function(createObjectMapper) {
+
+  /**
+   * The opposite of `_.mapValues`; this method creates an object with the
+   * same values as `object` and keys generated by running each own enumerable
+   * property of `object` through `iteratee`.
+   *
+   * @static
+   * @memberOf _
+   * @category Object
+   * @param {Object} object The object to iterate over.
+   * @param {Function|Object|string} [iteratee=_.identity] The function invoked
+   *  per iteration.
+   * @param {*} [thisArg] The `this` binding of `iteratee`.
+   * @returns {Object} Returns the new mapped object.
+   * @example
+   *
+   * _.mapKeys({ 'a': 1, 'b': 2 }, function(value, key) {
+   *   return key + value;
+   * });
+   * // => { 'a1': 1, 'b2': 2 }
+   */
+  var mapKeys = createObjectMapper(true);
+
+  return mapKeys;
+});

object/mapValues.js

@@ -1,4 +1,4 @@
-define(['../internal/baseCallback', '../internal/baseForOwn'], function(baseCallback, baseForOwn) {
+define(['../internal/createObjectMapper'], function(createObjectMapper) {
 
   /**
    * Creates an object with the same keys as `object` and values generated by
@@ -41,15 +41,7 @@ define(['../internal/baseCallback', '../internal/baseForOwn'], function(baseCall
    * _.mapValues(users, 'age');
    * // => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
    */
-  function mapValues(object, iteratee, thisArg) {
-    var result = {};
-    iteratee = baseCallback(iteratee, thisArg, 3);
-
-    baseForOwn(object, function(value, key, object) {
-      result[key] = iteratee(value, key, object);
-    });
-    return result;
-  }
+  var mapValues = createObjectMapper();
 
   return mapValues;
 });

object/omit.js

@@ -3,11 +3,6 @@ define(['../internal/arrayMap', '../internal/baseDifference', '../internal/baseF
   /**
    * The opposite of `_.pick`; this method creates an object composed of the
    * own and inherited enumerable properties of `object` that are not omitted.
-   * Property names may be specified as individual arguments or as arrays of
-   * property names. If `predicate` is provided it is invoked for each property
-   * of `object` omitting the properties `predicate` returns truthy for. The
-   * predicate is bound to `thisArg` and invoked with three arguments:
-   * (value, key, object).
    *
    * @static
    * @memberOf _

package.json

@@ -1,6 +1,6 @@
 {
   "name": "lodash",
-  "version": "3.7.0",
+  "version": "3.8.0",
   "main": "main.js",
   "private": true,
   "volo": {

support.js

@@ -20,6 +20,7 @@ define(['./internal/root'], function(root) {
 
   (function(x) {
     var Ctor = function() { this.x = x; },
+        args = arguments,
         object = { '0': x, 'length': x },
         props = [];
 
@@ -69,7 +70,7 @@ define(['./internal/root'], function(root) {
      * @type boolean
      */
     try {
-      support.nonEnumArgs = !propertyIsEnumerable.call(arguments, 1);
+      support.nonEnumArgs = !propertyIsEnumerable.call(args, 1);
     } catch(e) {
       support.nonEnumArgs = true;
     }

utility/callback.js

@@ -1,4 +1,4 @@
-define(['../internal/baseCallback', '../internal/isIterateeCall'], function(baseCallback, isIterateeCall) {
+define(['../internal/baseCallback', '../internal/isIterateeCall', '../internal/isObjectLike', './matches'], function(baseCallback, isIterateeCall, isObjectLike, matches) {
 
   /**
    * Creates a function that invokes `func` with the `this` binding of `thisArg`
@@ -42,7 +42,9 @@ define(['../internal/baseCallback', '../internal/isIterateeCall'], function(base
     if (guard && isIterateeCall(func, thisArg, guard)) {
       thisArg = null;
     }
-    return baseCallback(func, thisArg);
+    return isObjectLike(func)
+      ? matches(func)
+      : baseCallback(func, thisArg);
   }
 
   return callback;

utility/method.js

@@ -24,7 +24,7 @@ define(['../internal/invokePath', '../function/restParam'], function(invokePath,
   var method = restParam(function(path, args) {
     return function(object) {
       return invokePath(object, path, args);
-    }
+    };
   });
 
   return method;