added code to say that discrete types (nat, bool, char) are instances of cp_*_*.
added code to say that discrete types (nat, bool, char)
are instances of cp_*_*.

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle