add list type check

tests/test_lib_append.rs

@@ -328,4 +328,38 @@ mod append_lib_tests {
             result.to_string(),
         );
     }
+
+    #[test]
+    fn test_islist_t() {
+        let document = "(list? ())";
+        let result = "true";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms);
+        dynamic_stdlib(&mut syms, None);
+
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_islist_f() {
+        let document = "(list? 1223)";
+        let result = "false";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms);
+        dynamic_stdlib(&mut syms, None);
+
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
 }