Question

这是GHCi会议：

Prelude> words " one two three"
["one","two","three"]
Prelude> lines "\none\ntwo\nthree"
["","one","two","three"]

这种不一致是否有原因？如果是这样，它是什么？

Answer 1

lines是一个实际的广告素材：您可以使用它来分割'\n'字符处的任何字符串，然后使用unlines完美地重新组合它们。（好吧，差不多：让我们忽略尾随新行和Windows行结束。）

如果words仅使用' '而不是'\n'作为分隔符，则行为相同，那么它就不会按照我们想要的方式运行：例如，串

     "I will not buy this record\nit is scratched"

将分裂为

     ["I","will","not","buy","this","record\nit","is","scratched"]

words通过拆分任何空格来避免。

Prelude> words "I will not buy this record\nit is scratched"
["I","will","not","buy","this","record","it","is","scratched"]

这意味着 a）它无论如何都不是双射，因为空白的味道会丢失，而 b）你会得到很多“空字“当两个空格字符相邻时。

因此，words的明智行为就是将这样的空白压缩成一个空白。