The type of top-level `~` should refer `num` rather than `realint`

[minoki]

The SML Basis Library specifies the type of top-level ~ as

val ~ : num -> num  (* default: int -> int *)

i.e. word is accepted.

Appendix E should be updated accordingly.

[JohnReppy]

The Successor-ML Definition inherits this mistake from the Definition (revised). I suspect (although I don't remember) that the decision to overload negation on words was probably made after the Definition was published. I'll make the change to the TeX sources.