SearchAbout type.
Definition c_type_type :=
({| Expr.Impl := type
; Expr.Eqb := type_eq
; Expr.Eqb_correct := environ_lemmas.type_eq_true |}).
Parameter environ_eq : environ -> environ -> bool.

Axiom environ_eq_correct : forall x y, environ_eq x y = true -> x = y.
Definition environ_type :=
({| Expr.Impl := environ
; Expr.Eqb := environ_eq
; Expr.Eqb_correct := environ_eq_correct |}).