问题描述
我对Scala还是陌生的，尝试理解易变的 Seq 。由于它位于软件包 mutable 中，我希望有一种方法可以让我们在不复制整个集合的情况下追加元素。
I'm pretty new to Scala and try to understand mutable Seq. Since it's in package mutable I expected there is a method that allows us to append element without copying the whole collection.
但是 mutable.Seq + = 方法$ c>，但在 Buffer 中。 ：+ 和 +：都复制了集合。
But there is no += method in the mutable.Seq, but in Buffer is. :+ and +: both copy the collection.
为什么它是可变的？
推荐答案
因为可变和 growable 不是一回事。
（后者是前者的一种特定类型：所有可增长的东西都是可变的，但并不是所有可变的东西都是可变的。）
Because mutable and growable isn't the same thing. (the latter is one specific type of the former: everything, that's growable is mutable, but not everything that's mutable is growable).
mutable.Seq 具有 update ，可让您更改给定索引处的元素，但不会增大或缩小。
Buffer 是 Seq 的特化，既可变又可扩展。
mutable.Seq has update, that allows you to change the element at a given index, but it does not grow or shrink. Buffer is s specialization of Seq, that is both mutable and growable.
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