parentsTheory.parents : string -> string list
Lists the parent theories of a named theory.
If s is the name of the current theory or an ancestor of
the current theory, the call parents s returns a list of
strings that identify the parent theories of s. The
shorthand "-" may be used to denote the name of the current
theory segment.
Fails if the named theory is not an ancestor of the current theory.
> parents "bool";
val it = ["min"]: string list
> parents "min";
val it = []: string list
> current_theory();
val it = "foo": string
> parents "-";
val it = ["wombat"]: string list
Theory.ancestry, Theory.current_theory