The simplest expressions are constants. The boolean constants are \(\rm true\) and \(\rm false\). Integer constants are unsigned strings of digits such as \(\rm 0\), \(\rm 123\), and \(\rm 007\). String constants are sequences of characters enclosed in double quotes, such as \(\rm \LQT This\ is\ a\ string. \RQT\) String constants may be at most 1024 characters long. There are other restrictions on strings; see Section 10.
The constants belong to the basic classes \(\rm Bool\), \(\rm Int\), and \(\rm String\). The value of a constant is an object of the appropriate basic class.