more builtins

builtins/hash.go

@@ -0,0 +1,16 @@
+package builtins
+
+import "monkey/object"
+
+// HashOf ...
+func HashOf(args ...object.Object) object.Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1",
+			len(args))
+	}
+
+	if hash, ok := args[0].(object.Hashable); ok {
+		return &object.Integer{Value: int64(hash.HashKey().Value)}
+	}
+	return newError("argument #1 to `hash()` is not hashable: %s", args[0].Inspect())
+}