5.2 原子 Atoms

Atoms are the most basic elements of expressions. The simplest atoms are identifiers or literals. Forms enclosed in reverse quotes or in parentheses, brackets or braces are also categorized syntactically as atoms. The syntax for atoms is:

原子是表达式最基本的组成单位. 最简单的原子是标识符或者字面值. 以反引号,圆括号, 方括号或大括号括住的符号在句法上也看成是原子.原子的句法如下:

`atom`	::=	`identifier \| literal \| enclosure`
`enclosure`	::=	`parenth_form \| list_display`
		`\| dict_display \| string_conversion`