From 7caace8f13f8fa8454add31ada98976b45640af9 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Fri, 7 Oct 2016 23:54:47 -0400
Subject: [PATCH] Filter export lists for (only) and (except)

---
 scheme/cyclone/libraries.sld | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/scheme/cyclone/libraries.sld b/scheme/cyclone/libraries.sld
index 0b8d760e..3a6535c4 100644
--- a/scheme/cyclone/libraries.sld
+++ b/scheme/cyclone/libraries.sld
@@ -222,7 +222,20 @@
          (lib (read-all fp))
          (exports (lib:exports (car lib))))
     (close-input-port fp)
-    exports))
+    (cond
+      ((tagged-list? 'only import)
+       ;; Filter to symbols from "only" that appear in export list
+       (filter
+         (lambda (sym)
+           (member sym exports))
+         (cddr import)))
+      ((tagged-list? 'except import)
+       (filter
+         (lambda (sym)
+           (not (member sym (cddr import))))
+         exports))
+      (else 
+       exports))))
 
 ;; Take a list of imports and resolve it to the imported vars
 (define (lib:resolve-imports imports)