add builtin function for negation (#20)

JunNishimura · Sep 30, 2024 · ebd5e48 · ebd5e48
1 parent df37652
commit ebd5e48
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/evaluator/builtins.go b/evaluator/builtins.go
@@ -243,4 +243,13 @@ var builtins = map[string]*object.Builtin{
 			return True
 		},
 	},
+	"!": {
+		Fn: func(args object.Object) object.Object {
+			if args.Type() != object.BOOLEAN_OBJ {
+				return newError("argument to '!' must be BOOLEAN, got %s", args.Type())
+			}
+
+			return &object.Boolean{Value: !args.(*object.Boolean).Value}
+		},
+	},
 }