+ # Is the string non-empty but only made of whitespaces?
+ #
+ # assert " \n\t ".is_whitespace == true
+ # assert " hello ".is_whitespace == false
+ # assert "".is_whitespace == false
+ #
+ # `Char::is_whitespace` determines what is a whitespace.
+ fun is_whitespace: Bool
+ do
+ if is_empty then return false
+ for c in self.chars do
+ if not c.is_whitespace then return false
+ end
+ return true
+ end
+