Require Export QArith.
Local Notation " ' x " := (Zpos x) (at level 20, no associativity) : Z_scope.
Fixpoint pos_power2 (n:nat) : positive := match n with
| O => 1%positive
| S m => ((pos_power2 m)~0)%positive
end.
Definition dr2Q (x:dyadic_rational) : Q :=
match x with
| m_over_2_to_n m n => (Z_of_nat m) # (pos_power2 n)
end.

Lemma dr2Q_wd: forall x y:dyadic_rational,
dr_eq x y -> dr2Q x == dr2Q y.