Conditional expressions evaluate and return boolean (TRUE and FALSE) expressions for conditional and looping expressions. They can contain conditional operators, and and or.
Examples of conditional expressions:
; The branch is taken if SomeVar is TRUE, *or* both the following things are true: ; SomeOtherVar is TRUE and AnotherVar is FALSE. (if (or SomeVar (and SomeOtherVar (not AnotherVar))) (= x 10) else (= x 20) ) ; The or and and operators can take multiple arguments. In this case, if either SomeVar, ; AnotherVar or AThirdVar are TRUE, the branch will be taken. (if (or SomeVar AnotherVar AThirdVar) (= x 10) ) ; Sometimes it can be useful to place the condition terms on more than one line ; Here the branch is taken if the ego is on green, its x coordinate is less than 100, ; and it has the radio transmitter in its inventory. (if (and (& ctlGREEN (gEgo onControl:)) (< 100 (gEgo x?)) (gEgo has: INV_TRANSMITTER) ) (Print "The transmitter begins to beep") )