- (if <test> <consequent> <alternate>)syntax
- (if <test> <consequent>)syntax
Syntax: <Test>, <consequent>, and <alternate> may be arbitrary expressions.
Semantics: An if expression is evaluated as follows: first, <test> is evaluated. If it yields a true value (see the section about booleans below), then <consequent> is evaluated and its value(s) is(are) returned. Otherwise <alternate> is evaluated and its value(s) is(are) returned. If <test> yields a false value and no <alternate> is specified, then the result of the expression is unspecified.
(if (> 3 2) 'yes 'no) ===> yes (if (> 2 3) 'yes 'no) ===> no (if (> 3 2) (- 3 2) (+ 3 2)) ===> 1