#[global]
Instance CR_of_Q_morph_T
  : forall {R : ConstructiveReals}, CMorphisms.Proper
      (CMorphisms.respectful Qeq (CReq R)) (CR_of_Q R).

Lemma CR_of_Q_inv : forall {R : ConstructiveReals} (q : Q) (qPos : Qlt 0 q), CR_of_Q R (/q) == (/ CR_of_Q R q) (inr (CR_of_Q_pos q qPos)).