序列与LazyList [英] Sequence vs LazyList

问题描述

我无法围绕序列与 LazyList 之间的区别。他们都是懒惰的，潜在的无限的。而 seq<'T> 是.NET框架中的 IEnumerable<'T> ， LazyList 包含在 F＃PowerPack 中。实际上，我遇到的次序比 LazyList s更多。

I can't wrap my head around the differences between sequence and LazyList. They're both lazy and potentially infinite. While seq<'T> is IEnumerable<'T> from .NET framework, LazyList is included in F# PowerPack. In practice, I encounter sequences much more often than LazyLists.

他们的区别是什么的性能，使用，可读性等？与 seq 相比， c

What are their differences in terms of performance, usage, readability, etc? What are reasons for such a bad reputation of LazyList compared to that of seq?

推荐答案

LazyList 仅计算每个元素一次，而不管遍历列表多少次。以这种方式，它更接近于从 Seq.cache （而不是典型的序列）返回的序列。但是，除了缓存之外， LazyList 的行为完全像一个列表：它使用一个列表结构，并支持模式匹配。所以你可能会说：当你需要列表语义和缓存（除了懒惰）之后，使用 LazyList 而不是 seq 。

LazyList computes each element only once regardless of how many times the list is traversed. In this way, it's closer to a sequence returned from Seq.cache (rather than a typical sequence). But, other than caching, LazyList behaves exactly like a list: it uses a list structure under the hood and supports pattern matching. So you might say: use LazyList instead of seq when you need list semantics and caching (in addition to laziness).

关于无限， seq 的内存使用情况是不变的，而 LazyList 是线性的。

Regarding both being infinite, seq's memory usage is constant while LazyList's is linear.

这些 docs 可能值得一读。

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