IF

IF is a special form that evaluates its first argument. If the result is #f it skips its second argument and evaluates and returns its third element if any. If result of evaluating the first element was not #f, it evaluates the second argument and returns that.

> (define x 10)

10

> (if (> x 2) (- x 1) (+ x 1))

9

Previous slide

Back to first slide

View graphic version