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

Oh, and actually before you skip your page in the notes, I realized I should write out for you what the addition is to start with. So, when we're combining two waves, 1sb what we have is 1 s a that we're adding together with 1 s for b, the second atom.

在你们翻过这页讲义之前，我觉得我应该写出加法,当我们把两个波函数放在一起时，我们用1sa加上，第二个原子。

麻省理工公开课 - 化学原理课程节选