file read

Author: Javran

ty-scheme/ch07/file-ports.scm

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+(define out
+  (lambda (what)
+    (begin
+      (display what)
+      (newline))))
+
+(newline)
+
+; the s-expr below is identical
+;     current-output-port is used if no port is given
+
+(display 9)
+(display 9 (current-output-port))
+; 99
+
+(newline)
+
+; now we've known 'open-{input,output}-file' & 'close-{input,output}-port'
+; let's try to play with them, and do some IO operations
+
+(define infile (open-input-file "in.txt"))
+
+(out (read-char infile))
+; #\T
+
+(out (read-line infile))
+; "each"
+
+; write a function to read all the rest content!
+(define read-all
+  (lambda (port)
+    ; we keep a list for what we've read
+    (let read-next (
+      (cur-content '()))
+      (define cur-ch (read-char port))
+      (if (eof-object? cur-ch)
+	(list->string (reverse cur-content))
+	(read-next (cons cur-ch cur-content))))))
+(out (read-all infile))
+(close-input-port infile)

ty-scheme/ch07/in.txt

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+Teach
+Yourself
+Scheme
+in
+Fixnum
+Days
+Nice boat!