One important element of expressions is the variable.
表达式的重要元素是变量。
2
Note in the evaluation, if the pattern is a bound variable, or the element of the pattern is a bound variable, then the result of the pattern match becomes a comparison.
注意，如果模式是绑定的变量，或者模式的元素是绑定的变量，那么模式匹配的结果就会变成比较。
3
For this definition, add a with element and set the variable to activeMenuSelection.