From f6a8c75a6d704367bb6f1a443a326b92a06ff81b Mon Sep 17 00:00:00 2001
From: Masaya Tojo <masaya@tojo.tokyo>
Date: Sun, 29 Nov 2020 04:32:30 +0900
Subject: wip39

---
 vikalpa.scm | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/vikalpa.scm b/vikalpa.scm
index 0264ba9..27d09c8 100644
--- a/vikalpa.scm
+++ b/vikalpa.scm
@@ -168,8 +168,15 @@
 
 (define (expression-vars expr)
   (cond
-   ((pair? expr)
-    (apply lset-union eq?
+   ((expr-quoted? expr) '())
+   ((if-form? expr)
+    (lset-union eq?
+                (expression-vars (if-form-test expr))
+                (expression-vars (if-form-then expr))
+                (expression-vars (if-form-else expr))))
+   ((app-form? expr)
+    (apply lset-union
+           eq?
            (map expression-vars (app-form-args expr))))
    ((variable? expr) (list expr))
    (else '())))
-- 
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