rf-web/vendor/bundle/gems/rouge-3.12.0/lib/rouge/demos/racket
2019-10-21 10:18:17 +02:00

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#lang racket
;; draw a graph of cos and deriv^3(cos)
(require plot)
(define ((deriv f) x)
(/ (- (f x) (f (- x 0.001))) 0.001))
(define (thrice f) (lambda (x) (f (f (f x)))))
(plot (list (function ((thrice deriv) sin) -5 5)
(function cos -5 5 #:color 'blue)))
;; Print the Greek alphabet
(for ([i (in-range 25)])
(displayln
(integer->char
(+ i (char->integer #\u3B1)))))
;; An echo server
(define listener (tcp-listen 12345))
(let echo-server ()
(define-values (in out) (tcp-accept listener))
(thread (λ ()
(copy-port in out)
(close-output-port out)))
(echo-server))