发布于 2014-10-08 23:47:39 | 106 次阅读 | 评论: 0 | 来源: 网友投递
Immutable.js 不可变数据集合
Immutable 是 Facebook 开发的不可变数据集合。不可变数据一旦创建就不能被修改，是的应用开发更简单，允许使用函数式编程技术，比如惰性评估。Immutable JS 提供一个惰性 Sequence，允许高效的队列方法链，类似 map 和 filter ，不用创建中间代表。
Immutable.js 2.2.1 发布，此版本现已提供下载，更新内容如下：
新特性：
groupBy and countBy now return Sequence instead of Map.
Bug 修复
Fix issue where seq.flip().reverse() can result in incorrect value.
在 2.2.1 发布前两个小时还发布了 Immutable.js 2.2.0 版本，更新内容如下：
新特性
mapEntries() works like map and mapKeys, but accepts and returns [key, value] tuples, enabling mapping both keys and values simultaniously.
toKeyedSeq() converts an IndexedSequence into a Sequence where the indices are treated as keys. This is a lazy operation.
The whole IndexedSequence API has been reworked to remove the third maintainIndices argument from many methods. Using maintainIndices resulted in a sparse IndexedSequence, which no longer made sense in the context of dense IndexedSequences.
示例：
// Old: [0,,2,,4,,6,,8,,]
Range(0,10).filter(isEven, null, true)
// New: { 0: 0, 2: 2, 4: 4, 6: 6, 8: 8 }
Range(0,10).toKeyedSeq().filter(isEven)
Bug 修复：
Returning false from forEach() often resulted in an incorrect length iterated. Clarified the documentation describing this behavior and corrected any bad behavior.
Fixed some documentation which referenced sparse behavior.
Fixed some issues when using reverse() and take() or skip() in concert that resulted in incorrect indices.
Fixed incorrect behavior when take() or skip() are given negative values.
Fixed issue where iteration of valueSeq() didn't provide the correct collection as a third argument.
Fixed issue where flatten() and concat() behavior diverged.
更多内容请看发行说明。
Immutable 是 Facebook 开发的不可变数据集合。不可变数据一旦创建就不能被修改，是的应用开发更简单，允许使用函数式编程技术，比如惰性评估。Immutable JS 提供一个惰性 Sequence，允许高效的队列方法链，类似 map 和 filter ，不用创建中间代表。
immutable 通过惰性队列和哈希映射提供 Sequence, Range, Repeat, Map, OrderedMap, Set 和一个稀疏 Vector。