元数据读取器语法何时从＃^更改为^？ [英] When did the metadata reader syntax change from #^ to ^?

问题描述

目前（Clojure v1.6）你可以用两种方式给出类型提示：

  ^ float xs 
  

 ＃^ floats xs 
  

根据 Clojure ^ floats vs.＃^ floats？ ，后者是传统语法，前者是当前的首选形式。

解决方案

^ 宏字符的简要历史

• 在Clojure v1.0中， ^ 元读取器宏。换句话说， ^ x 是（meta x）的缩写。 ＃^ 用于将元数据与对象相关联。 （请参见2009年11月宏字符文档。）

  ^ ，都与元数据相关，令人困惑。 他们决定弃用 ^ ，计划最终用 ^ 替换＃^ 。在Clojure v1.1中， ^ 阅读器宏已正式弃用。 （请参阅2010年1月起的宏字符文档。）




• 2010年4月26日，在Github上提交了提交将 ^ 行为替换为＃^ 行为。 （这是＃^ 和 ^ 成为同义词。）




• 在Clojure v1.2版本中， ＃^ 已弃用，赞成 ^ 。 （请参阅2010年8月起的宏字符文档 a>。）




• 他们删除了最后一个

$ b $
b

Currently (Clojure v1.6) you can give a type hint two ways:

^floats xs

#^floats xs

According to Clojure ^floats vs. #^floats?, the latter is legacy syntax, and the former is the current preferred form.

When did that change happen?

解决方案

A brief history of the ^ macro character

• In Clojure v1.0, the ^ character is the "meta reader macro". In other words, ^x was shorthand for (meta x). #^ was used to associate metadata with an object. (See the Macro Characters documentation from November 2009.)

• At some point, someone probably realized that having special cases for both #^ and ^, both related to metadata, was confusing. They decided to deprecate ^, with the plan to eventually replace #^ with ^. In Clojure v1.1, the ^ reader macro was officially deprecated. (See the Macro Characters documentation from January 2010.)

• There's a commit on April 26, 2010 on Github that replaces the old ^ behavior with the #^ behavior. (This is when #^ and ^ became synonymous.)

• In the Clojure v1.2 release, #^ was deprecated in favor of ^. (See the Macro Characters documentation from August 2010.)

• They removed the last few instances of #^ from clojure.core back in 2013, sometime before the Clojure v1.6 release.

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