update

Task/Hello-world-Line-printer/Racket/hello-world-line-printer.rkt

@@ -0,0 +1,11 @@
+#lang racket
+(define (print text)
+  ;; try lpr first
+  (define lpr-exe (find-executable-path "lpr"))
+  ;; otherwise use a special file
+  (if lpr-exe
+    (with-input-from-string (~a text "\n") (λ() (void (system* lpr-exe))))
+    (with-output-to-file #:exists 'append
+      (case (system-type) [(windows) "PRN"] [else "/dev/lp0"])
+      (λ() (displayln text)))))
+(print "Hello World!")