Referenz und Spickzettel

#lang racket

(define (zeige name wert) (printf "~a ~a~n" (~a name #:min-width 22) wert))
(zeige "(string? \"a\")" (string? "a"))
(zeige "(symbol? 'a)" (symbol? 'a))
(zeige "(list? '())" (list? '()))
(zeige "(pair? '(1))" (pair? '(1)))
(zeige "(equal? '(1) '(1))" (equal? '(1) '(1)))
(zeige "(eq? 'a 'a)" (eq? 'a 'a))
(zeige "(eqv? 2.0 2.0)" (eqv? 2.0 2.0))
(zeige "(= 1 1.0)" (= 1 1.0))
(zeige "(void)" (void))
(zeige "(length '())" (length '()))
(zeige "(string->symbol \"x\")" (string->symbol "x"))
(zeige "(procedure? car)" (procedure? car))
(zeige "(exact->inexact 22/7)" (exact->inexact 22/7))
(zeige "(string<? \"b\" \"a\")" (string<? "b" "a"))

(string? "a")          #t
(symbol? 'a)           #t
(list? '())            #t
(pair? '(1))           #t
(equal? '(1) '(1))     #t
(eq? 'a 'a)            #t
(eqv? 2.0 2.0)         #t
(= 1 1.0)              #t
(void)                 #<void>
(length '())           0
(string->symbol "x")   x
(procedure? car)       #t
(exact->inexact 22/7)  3.142857142857143
(string<? "b" "a")     #f

#lang racket
(displayln (unbekannt 1))

unbekannt: unbound identifier

#lang racket
(displayln (+ 1 "2"))

+: contract violation