we need batch io for htdp/2e

svn: r14503

collects/2htdp/batch-io.ss

@@ -0,0 +1,31 @@
+#lang scheme/base
+
+(require htdp/error)
+
+(define (read-file f)
+  (check-arg 'read-file (string? f) "string" "first" f)
+  (check-arg 'read-file (file-exists? f) "name of file in program's folder" "first" f)
+  (list->string
+    (with-input-from-file f 
+      (lambda ()
+	(let loop ()
+	  (define nxt (read-char))
+	  (if (eof-object? nxt) '() (cons nxt (loop))))))))
+ 
+(define (write-file f str)
+  (check-arg 'read-file (string? f) "string" "first" f)
+  (let ([result (not (file-exists? f))])
+    (with-output-to-file f 
+      (lambda () (printf "~a" str))
+      #:exists 'truncate)
+    result))
+
+(provide 
+ read-file ;; String -> String
+ ;; read the file f (in current-directory) as a string
+ 
+ write-file ;; String String -> Boolean
+ ;; write str to file f (in current-directory); 
+ ;; false, if f exists
+ ;; true, if f doesn't exist
+ )

collects/2htdp/universe.ss

@@ -1,7 +1,7 @@
 #lang scheme/gui
 
 #| TODO: 
-   -- make window resizable :: why? 
+   -- make window resizable :: why
 |#
 
 (require (for-syntax "private/syn-aux.ss")