What is the difference in usage between 夜【よ】 and 夜【よる】？


As I understand, both よ and よる mean 'night'. I guess that the difference might
be purely idiomatic. In this sense:

  * What are idioms where only one of them is correct? 
  * What are idioms where you can use either? 
  * If you can use either, is there a difference in nuance?




Both readings are kun-readings of kanji 夜 and are used in native Japanese
words.

I think the main difference is that:

  * 夜{よる} is rather used as a standalone word meaning evening or night.

  * 夜{よ} is used in compound words, e.g. 夜{よ}中{なか} (midnight), 闇{やみ}夜{よ} (dark night), 夜{よ}空{ぞら} (night sky).

