2.12 Conditionals: if, cond, and, and or
Conditionals in The Racket Guide introduces conditionals.
(if testexpr thenexpr elseexpr)
Examples:  

(cond condclause ...)
condclause = [testexpr thenbody ...+]  [else thenbody ...+]  [testexpr => procexpr]  [testexpr]
Chaining Tests: cond in The Racket Guide introduces cond.
A condclause that starts with else must be the last condclause.
If no condclauses are present, the result is #<void>.
If only a [else thenbody ...+] is present, then the thenbodys are evaluated. The results from all but the last thenbody are ignored. The results of the last thenbody, which is in tail position with respect to the cond form, are the results for the whole cond form.
Otherwise, the first testexpr is evaluated. If it produces #f, then the result is the same as a cond form with the remaining condclauses, in tail position with respect to the original cond form. Otherwise, evaluation depends on the form of the condclause:
[testexpr thenbody ...+] The thenbodys are evaluated in order, and the results from all but the last thenbody are ignored. The results of the last thenbody, which is in tail position with respect to the cond form, provides the result for the whole cond form.
[testexpr => procexpr] The procexpr is evaluated, and it must produce a procedure that accepts one argument, otherwise the exn:fail:contract exception is raised. The procedure is applied to the result of testexpr in tail position with respect to the cond expression.
[testexpr] The result of the testexpr is returned as the result of the cond form. The testexpr is not in tail position.
Examples:  

(and expr ...)
Combining Tests: and and or in The Racket Guide introduces and.
If no exprs are provided, then result is #t.
If a single expr is provided, then it is in tail position, so the results of the and expression are the results of the expr.
Otherwise, the first expr is evaluated. If it produces #f, the result of the and expression is #f. Otherwise, the result is the same as an and expression with the remaining exprs in tail position with respect to the original and form.
Examples:  

(or expr ...)
Combining Tests: and and or in The Racket Guide introduces or.
If no exprs are provided, then result is #f.
If a single expr is provided, then it is in tail position, so the results of the or expression are the results of the expr.
Otherwise, the first expr is evaluated. If it produces a value other than #f, that result is the result of the or expression. Otherwise, the result is the same as an or expression with the remaining exprs in tail position with respect to the original or form.
Examples:  
