WriteLn used to be the PascalLanguage version of printf. Fortunately, CeeLanguage came up and gave us a much improved thing called "printf", which at least did not bother being type safe or convenient to use. The problem with WriteLn is that it is in general difficult to define in a library.
LxLanguage has type-safe, variable argument size functions, so you can define WriteLn.
procedure WriteLn() is
Write lineTermination -- Whatever that is
procedure WriteLn(writable X; other) is