Immutable.js 2.5.0 发布，不可变数据集合

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Immutable.js 2.5.0 发布，此版本现已提供下载，更新内容如下：

新特性：

• seq.toStack() as alias for Stack(seq)

• flatten now accepts a depth number or shallow boolean to describe how deep it should flatten, by default it now flattens deeply.

Bug 修复：

• Cursors can now represent Indexed sequences #97

• Readme updates: explain CDN, update examples.

• record.clear() no longer mysteriously vanishes.

• Unsafe get and has optimizations removed from ValuesSeq.

• last on a sequence with unknown length no longer returns undefined #141

• seq.reverse().get(i) no longer returns incorrect values for indexed sequences.

• seq.filter().get(i) no longer returns incorrect values for indexed sequences.

• flatten no longer flattens sequencible values (string, array, object), but only Sequence instances, leading to more predictable flattening.

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。