From 0aba8feb87cab378ea3f15855391f9165578db4f Mon Sep 17 00:00:00 2001
From: HAYAMA Kaoru <3752189+hymkor@users.noreply.github.com>
Date: Tue, 26 Aug 2025 02:31:17 +0900
Subject: [PATCH] Replace `IsNull` with `IsNone`

---
 global.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/global.go b/global.go
index fa661cd..3d8cbd2 100644
--- a/global.go
+++ b/global.go
@@ -208,7 +208,7 @@ func (env *Env) setenv(ctx context.Context, w *gmnlisp.World, __key, __val gmnli
 	}
 	key := string(_key)
 
-	if gmnlisp.IsNull(__val) {
+	if gmnlisp.IsNone(__val) {
 		return gmnlisp.Null, os.Unsetenv(key)
 	}
 	_val, err := gmnlisp.ExpectClass[gmnlisp.String](ctx, w, __val)