Prev Up Next
Like all languages, Scheme provides conditionals. The basic form is the if:
(if test-expression
then-expression
else-expression)
If test-expression evaluates to true (ie, any value other
than #f), the then-expression is evaluated. If
not, the else-expression is evaluated.
else-expression is optional.
(if (= (+ 2 3) 5)
'schemes-addition-works!)
=> schemes-addition-works!
(if (< 3 2)
'three-is-less-than-two
'three-isnt-less-than-two)
=> three-isnt-less-than-two
Scheme provides some other conditional forms for
convenience. They can all be defined as macros
(chap 8) that expand
into if-expressions.
Prev Up Next