If you're writing a one line function, whose sole purpose in life is addition, and, clearly, this is about addition, well, then it's, in fact, A reasonable to use a shorter symbol like A, but I do have to specify it's type.

如果你在写一个一行的函数，它唯一的目的是,做加法，显然这是关于加法的，好的，实际上，用一个短的标识符是合理的，像，但是我必须指明它的类型。

哈佛公开课 - 计算机科学课程节选

Spelling. These are just dumb little things to look for. Did you spell all the identifiers the way you think you did. The problem is, when you read code you see what you expect to see.

拼写错误，你可能得找找这些粗心的小错误,你是否拼对了标识符,问题是当你阅读代码的时候,你看到的都是你以为的。

麻省理工公开课 - 计算机科学及编程导论课程节选