Module Loc.
Definition type (l: loc) : typ :=
match l with
| R r => mreg_type r
| S sl pos ty => ty
end.
Definition diff_dec (l1 l2: loc) : { Loc.diff l1 l2 } + { ~Loc.diff l1 l2 }.

Lemma in_notin_diff:
forall l1 l2 ll, notin l1 ll -> In l2 ll -> diff l1 l2.