Section ExtensionalEquality.
Variables A B C : Type.
Definition eqfun (f g : B -> A) : Prop := forall x, f x = g x.
Definition eqrel (r s : C -> B -> A) : Prop := forall x y, r x y = s x y.

Lemma frefl f : eqfun f f. Proof. by []. Qed.
Lemma fsym f g : eqfun f g -> eqfun g f. Proof. by move=> eq_fg x. Qed.