add a write-to-file function for exporting stuff

ffmpeg-myth.scm

@@ -27,6 +27,14 @@
 
 (define (roundx x) (inexact->exact (round x)))
 
+(define (write-to-file obj filename)
+  (let ((port (open-file filename "w")))
+    (catch 'write-error
+      ;; thunk
+      (lambda () (simple-format port "~a" obj) (force-output) (close port))
+      ;; handler
+      (lambda () (close port) 'write-error))))
+
 (define* (shell-command-to-string* cmd args)
   (let* ((port (apply open-pipe* (append (list OPEN_READ cmd) args)))
 	 (str (read-string port)))