Добре дошли в DrRacket, версия 7.0 [3m].
Език: R5RS; memory limit: 128 MB.
> 2
2
> 2 + 3
2
#<procedure:+>
3
> (+ 2 3)
5
> (2 + 3)
. . application: not a procedure;
 expected a procedure that can be applied to arguments
  given: 2
  arguments...:
> "ФП"
"ФП"
> \#a
. . |#a|: undefined;
 cannot reference an identifier before its definition
> #\a
#\a
> 1.213
1.213
> a
. . a: undefined;
 cannot reference an identifier before its definition
> (+ 2 3)
5
> +
#<procedure:+>
> (quote +)
+
> ('+ 2 3)
. . application: not a procedure;
 expected a procedure that can be applied to arguments
  given: +
  arguments...:
> (define (f x y) (+ (square (1+ x)) (square y) 5))
> squarre
. . squarre: undefined;
 cannot reference an identifier before its definition
> square
. . square: undefined;
 cannot reference an identifier before its definition
> 1+
. . 1+: undefined;
 cannot reference an identifier before its definition
> f
#<procedure:f>
> (f 2 4)
. . square: undefined;
 cannot reference an identifier before its definition
> (define (square x) (* x x))
> square
#<procedure:square>
> (f 2 4)
. . 1+: undefined;
 cannot reference an identifier before its definition
> (define (1+ k) (+ k 1))
> (f 2 4)
30
> (define (g x) (- (g (1+ x)) 1))
> (g 0)

Interactions disabled

> (+ 1 2 3 4 5)
15
> (+ 1)
1
> (+)
0
> (- 15 5 4 3 2)
1
> (- 15)
-15
> (-)
. . -: arity mismatch;
 the expected number of arguments does not match the given number
  expected: at least 1
  given: 0
> (*)
1
> (/ 32 2 2 2 2)
2
> (/ 32)
1/32
> (/)
. . /: arity mismatch;
 the expected number of arguments does not match the given number
  expected: at least 1
  given: 0
> (boolean? #t)
#t
> (boolean? #f)
#t
> (boolean? 2)
#f
> (symbol? +)
#f
> (procedure? +)
#t
> (symbol? '+)
#t
> (symbol? symbol?)
#f
> (symbol? '
           symbol?)
#t
> (procedure? procedure?)
#t
> (and #t)
#t
> (or #t)
#t
> (and)
#t
> (or)
#f
>