Welcome to DrRacket, version 8.4 [cs].
Language: Determine language from source; memory limit: 128 MB.
> 1
1
> 56
56
> 56.7
56.7
> 1/5
1/5
> (circle 20 "solid" "blue")
...
> "abc"
"abc"
> 'abc
'abc
> abc
. . abc: undefined;
 cannot reference an identifier before its definition
> '(+ 1 2)
'(+ 1 2)
> (+ 1 2)
3
> (eval '(+ 1 2))
3
> (cons 1 2)
'(1 . 2)
> '()
'()
> (list 1 2 3 4 5)
'(1 2 3 4 5)
> (cons 1 '(2 3 4))
'(1 2 3 4)
> (cons 1 '())
'(1)
> (cons 2 (cons 1 '()))
'(2 1)
> (length (cons 2 (cons 1 '())))
2
> (length (cons 1 2))
. . length: contract violation
  expected: list?
  given: '(1 . 2)
> (if #f (length (cons 1 2)) 5)
5
> (car (cons 1 2))
1
> (cdr (cons 1 2))
2
> (first (cons 1 2))
. . first: contract violation
  expected: (and/c list? (not/c empty?))
  given: '(1 . 2)
> (first (list 1 2))
1
> (second (list 1 2))
2
> (car (list 1 2 3 4 5))
1
> (cdr (list 1 2 3 4 5))
'(2 3 4 5)
> (cdr (list 1))
'()
> 

> (foldl + (list 1 2 3 4 5))
. . foldl: arity mismatch;
 the expected number of arguments does not match the given number
  expected: at least 3
  given: 2
> (foldl + 0 (list 1 2 3 4 5))
15
> 
> (1 2 3 4)
. . application: not a procedure;
 expected a procedure that can be applied to arguments
  given: 1
> 
> (map (λ (x) (+ x 1)) '(1 2 3 4 5))
'(2 3 4 5 6)
> 
> #t
#t
> #f
#f
>