From 68fedae3ffa8b35bcbdc4a0f7c08e8544c827d56 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Tue, 23 Jun 2015 21:00:28 -0400
Subject: [PATCH] Initial version of with-output-to-file, still needs debugging

---
 scheme/file.sld | 25 ++++++++++++++++++++-----
 test2.scm       |  3 ++-
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/scheme/file.sld b/scheme/file.sld
index 328d2b3a..0a083341 100644
--- a/scheme/file.sld
+++ b/scheme/file.sld
@@ -1,9 +1,15 @@
 (define-library (scheme file)
   (export
-    call-with-input-file
+    call-with-input-file 
     call-with-output-file
-    with-input-from-file
-    with-output-from-file
+    ;delete-file 
+    ;file-exists?
+    ;open-binary-input-file 
+    ;open-binary-output-file
+    ;open-input-file 
+    ;open-output-file
+    with-input-from-file 
+    with-output-to-file
   )
   (import (scheme base))
   (begin
@@ -11,6 +17,15 @@
       (call-with-port (open-input-file string) proc))
     (define (call-with-output-file string proc)
       (call-with-port (open-output-file string) proc))
-    TODO: with-input-from-file
-    TODO: with-output-from-file
+    (define (with-input-from-file string thunk) #f)
+    (define (with-output-to-file string thunk)
+      ;; Have to do this the long way since parameterize is not available
+      (let ((old (current-output-port))
+            (new (current-output-port '<param-convert> (open-output-file string))))
+        (dynamic-wind
+          (lambda () (current-output-port '<param-set!> new))
+          thunk
+          (lambda () 
+            (close-port (current-output-port))
+            (current-output-port '<param-set!> old)))))
 ))
diff --git a/test2.scm b/test2.scm
index 25d29577..ba3e1c8f 100644
--- a/test2.scm
+++ b/test2.scm
@@ -1,5 +1,6 @@
 (import (scheme base)
-        (scheme file))
+        (scheme file)
+        (scheme write))
 
 (with-output-to-file 
   "test.out"