Welcome to DrRacket, version 8.11 [cs].
Language: racket, with debugging; memory limit: 128 MB.
> (+ 3 4)
7
> '(+ 3 4)
'(+ 3 4)
> '((+ 3 4))
'((+ 3 4))
> '((((()))))
'((((()))))
> (car '( 3 4))
3
> (car '((+ 3 4)))
'(+ 3 4)
> (car '((())))
'(())
> (car (+ 3 4))
. . car: contract violation
  expected: pair?
  given: 7
> (car 7)
. . car: contract violation
  expected: pair?
  given: 7
> (cdr '(+ 4 5))
'(4 5)
> (cdr (cdr '(+ 4 5)))
'(5)
> (cdr '())
. . cdr: contract violation
  expected: pair?
  given: '()
> (cons 1 '(3 4))
'(1 3 4)
> a
. . a: undefined;
 cannot reference an identifier before its definition
> (cons 'a '(b c))
'(a b c)
> (car (cons 'a '(b c)))
'a
> '(a b c)
'(a b c)
> (cons 'a (cons 'b (cons 'c '())))
'(a b c)
> (list? '(a b c))
#t
> (list? 3)
#f
> (list? 'a)
#f
> (a . b)
. #%app: bad syntax in: (#%app a . b)
> '(a . b)
'(a . b)
> (list? '(a . b))
#f
> (cons 'a '(b))
'(a b)
> (cons 'a 'b)
'(a . b)
> (cons 'a (cons 'b '()))
'(a b)
> (pair? '(a . b))
#t
> (list 'a 'b '(c d) 'e)
'(a b (c d) e)
> 4
4
> (+ 3 5)
8
> (number? 8)
#t
> (number? (+ 3 5))
#t
> (symbol? 4)
#f
> (symbol? '4)
#f
> (symbol? 'a)
#t
> (symbol? a)
. . a: undefined;
 cannot reference an identifier before its definition
> a
. . a: undefined;
 cannot reference an identifier before its definition
>