diff --git a/stl/lib.nas b/stl/lib.nas
index a271acd..4565162 100644
--- a/stl/lib.nas
+++ b/stl/lib.nas
@@ -139,7 +139,8 @@ var math=
     ln:    func(x)  {return __builtin_ln(x);     },
     sqrt:  func(x)  {return __builtin_sqrt(x);   },
     atan2: func(x,y){return __builtin_atan2(x,y);},
-    nan:   func()   {return 1/0-1/0;             },
+    inf:   1/0,
+    nan:   1/0-1/0,
     isnan: func(x)  {return __builtin_isnan(x);  }
 };
 
diff --git a/stl/result.nas b/stl/result.nas
new file mode 100644
index 0000000..e7b4159
--- /dev/null
+++ b/stl/result.nas
@@ -0,0 +1,28 @@
+
+import("lib.nas");
+var ResultTrait={
+    Ok:func(val){
+        me.ok=val;
+        me.flag=0;
+        return me;
+    },
+    Err:func(info){
+        me.err=info;
+        me.flag=1;
+        return me;
+    },
+    unwrap:func(){
+        if(me.flag)
+            die("error: "~me.err);
+        return me.ok;
+    }
+};
+
+var Result=func(){
+    return{
+        ok:nil,
+        err:"",
+        flag:1,
+        parents:[ResultTrait]
+    };
+};
\ No newline at end of file
diff --git a/test/exception.nas b/test/exception.nas
new file mode 100644
index 0000000..5e0ecc6
--- /dev/null
+++ b/test/exception.nas
@@ -0,0 +1,39 @@
+import("lib.nas");
+
+var ResultTrait={
+    Ok:func(val){
+        me.ok=val;
+        me.flag=0;
+        return me;
+    },
+    Err:func(info){
+        me.err=info;
+        me.flag=1;
+        return me;
+    },
+    unwrap:func(){
+        if(me.flag)
+            die("error: "~me.err);
+        return me.ok;
+    }
+};
+
+var Result=func(){
+    return{
+        ok:nil,
+        err:"",
+        flag:1,
+        parents:[ResultTrait]
+    };
+};
+
+var a=func(){
+    return Result().Ok("hello world");
+}
+
+var b=func(){
+    return Result().Err("unknown");
+}
+
+println(a().unwrap());
+b().unwrap();
\ No newline at end of file