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Task/Unix-ls/Racket/unix-ls.rkt

@@ -0,0 +1,20 @@
+#lang racket/base
+
+;; Racket's `directory-list' produces a sorted list of files
+(define (ls) (for-each displayln (directory-list)))
+
+;; Code to run when this file is running directly
+(module+ main
+  (ls))
+
+(module+ test
+  (require tests/eli-tester racket/port racket/file)
+  (define (make-directory-tree)
+    (make-directory* "foo/bar")
+    (for ([f '("1" "2" "a" "b")])
+      (with-output-to-file (format "foo/bar/~a"f) #:exists 'replace newline)))
+  (make-directory-tree)
+  (define (ls/str dir)
+    (parameterize ([current-directory dir]) (with-output-to-string ls)))
+  (test (ls/str "foo") => "bar\n"
+        (ls/str "foo/bar") => "1\n2\na\nb\n"))