Execute HQ9+: Difference between revisions
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See [[RCHQ9+/Python]].
=={{header|Racket}}==
Getting HQ9+ code from standard output is not easy without a trailing newline.
So I've extended the language (maybe the program could do with a flag to allow/
disallow newlines). To make up for that slackness, this implementation is
strictly case-sensitive.
<lang racket>#lang racket
; if we `for` over the port, we won't have the program in memory for 'Q'
(define (parse-HQ9+ the-program)
(define oTW " on the wall")
(and ; ensures the accumulator is never seen!
(for/fold ((A 0))
((token (in-string the-program)))
(case token
((#\H) (display "hello, world") A)
((#\Q) (display the-program) A)
;; official esolang version of 99-BoB at:
;; http://esolangs.org/wiki/99_bottles_of_beer
((#\9)
(displayln
(let ((BoB (lambda (n)
(string-append
(case n ((1) "1 bottle") ((0) "No bottles")
(else (format "~a bottles" n)))
" of beer"))))
(string-join
(for/list ((btls (in-range 99 0 -1)))
(string-append (BoB btls)oTW",\n"(BoB btls)
".\nTake one down, pass it around,\n"
(BoB (sub1 btls))oTW"."))
"\n\n"))) A)
((#\+) (add1 A))
((#\newline) ; language extension, makes getting standard in easier
(eprintf "warning: HQ9+: language extension ~s" token)
A)
(else (error "syntax error: HQ9+: unrecognised token ~s" token))))
(void)))
(module+ main (parse-HQ9+ (port->string)))
(module+ test
(require rackunit)
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ ""))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "H"))) "hello, world")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "Q"))) "Q")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "QQ"))) "QQQQ")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "+"))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "+"))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "++"))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "+++"))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ "+++++++++++++++++"))) "")
(check-equal? (with-output-to-string (lambda () (parse-HQ9+ (make-string 10000 #\+)))) "")
;;; you can jolly well read (and sing along to) the output of '9'
)</lang>
=={{header|REXX}}==
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