在Haskell中，Lazy ByteString的调用长度会将整个字符串强制到内存中吗？ [英] In Haskell, will calling length on a Lazy ByteString force the entire string into memory?

问题描述

我正在使用懒惰的字节读取大量数据流，并且想知道解析它时是否至少有X个字节可用。也就是说，我想知道字节串是否至少有X字节长。

会调用 length 导致整个流得到加载，因此击败了使用懒惰字节串的目的？

如果是，那么后续将是：如何判断它是否至少有X字节没有加载整个流？

编辑：最初我问在阅读文件的上下文，但明白，有更好的方式来确定文件大小。我需要的终极解决方案不应该依赖懒惰的bytestring源代码。

长度。取x 。

I am reading a large data stream using lazy bytestrings, and want to know if at least X more bytes is available while parsing it. That is, I want to know if the bytestring is at least X bytes long.

Will calling length on it result in the entire stream getting loaded, hence defeating the purpose of using the lazy bytestring?

If yes, then the followup would be: How to tell if it has at least X bytes without loading the entire stream?

EDIT: Originally I asked in the context of reading files but understand that there are better ways to determine filesize. Te ultimate solution I need however should not depend on the lazy bytestring source.

解决方案

Yes.

length . take x.

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