名称“xs”在哪里？模式匹配来自哪里？ [英] Where does the name "xs" for pattern matching come from?

问题描述

可能重复：

变量名称x和xs的历史记录是什么？

模式匹配中的规范名称xs来自哪里？

例如。在

  reverse'[] = [] 
 reverse'[x] = [x] 
 reverse '（x：xs）= reverse'xs ++ [x] 
  

它应该是复数x？

解决方案

这是我一直阅读的方式，你有单数和复数，所以 x：xs 或 y：ys 等。

它本身并没有任何意义，它只是一个约定。

IIRC它也在学习你一个Haskell 。

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编辑

我的错误 - 实际上是在真实世界Haskell 的类型和函数一章。

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Possible Duplicate:
What is the history of the variable names x and xs?

Where does the canonical name "xs" in pattern matching come from?

e.g. in

reverse' []     = []
reverse' [x]    = [x]
reverse' (x:xs) = reverse' xs ++ [x]  

Is it supposed to be the plural of "x" ?

解决方案

That's the way I've always read it, you have the singular and the plural, So x:xs or y:ys etc.

It doesn't actually have any meaning by itself, it's just a convention.

IIRC it's also mentioned in Learn You a Haskell.

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Edited

My mistake - it's actually in Real World Haskell in the chapter on types and functions.

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