Add Parametric Morphism {R : ConstructiveReals} : CRmin
    with signature (CReq R) ==> (CReq R) ==> (CReq R)
      as CRmin_morph.#[global]
Instance CRmin_morphT
  : forall {R : ConstructiveReals},
    CMorphisms.Proper
      (CMorphisms.respectful (CReq R) (CMorphisms.respectful (CReq R) (CReq R))) (@CRmin R).

Lemma CRmin_left : forall {R : ConstructiveReals} (x y : CRcarrier R), x <= y -> CRmin x y == x.