diff --git a/theories/tactics.v b/theories/tactics.v index a9a76e876798feba38e589983793aefc3887df4f..45d975a5e1c611e5442d14f27450aa2b18fe4935 100644 --- a/theories/tactics.v +++ b/theories/tactics.v @@ -229,30 +229,23 @@ Ltac setoid_subst := | H : @equiv ?A ?e _ ?x |- _ => symmetry in H; setoid_subst_aux (@equiv A e) x end. -(** f_equiv solves goals of the form "f _ = f _", for any relation and any - number of arguments, by looking for appropriate "Proper" instances. - If it cannot solve an equality, it will leave that to the user. *) +(** f_equiv works on goals of the form "f _ = f _", for any relation and any + number of arguments. It looks for an appropriate "Proper" instance, and + applies it. *) Ltac f_equiv := - (* Deal with "pointwise_relation" *) - repeat lazymatch goal with - | |- pointwise_relation _ _ _ _ => intros ? - end; - (* Normalize away equalities. *) - simplify_eq; - (* repeatedly apply congruence lemmas and use the equalities in the hypotheses. *) - try match goal with - | _ => first [ reflexivity | assumption | symmetry; assumption] + match goal with + | _ => reflexivity (* We support matches on both sides, *if* they concern the same variable. TODO: We should support different variables, provided that we can derive contradictions for the off-diagonal cases. *) | |- ?R (match ?x with _ => _ end) (match ?x with _ => _ end) => - destruct x; f_equiv + destruct x (* First assume that the arguments need the same relation as the result *) | |- ?R (?f ?x) (?f _) => - apply (_ : Proper (R ==> R) f); f_equiv + apply (_ : Proper (R ==> R) f) | |- ?R (?f ?x ?y) (?f _ _) => - apply (_ : Proper (R ==> R ==> R) f); f_equiv + apply (_ : Proper (R ==> R ==> R) f) (* Next, try to infer the relation. Unfortunately, there is an instance of Proper for (eq ==> _), which will always be matched. *) (* TODO: Can we exclude that instance? *) @@ -260,15 +253,28 @@ Ltac f_equiv := query for "pointwise_relation"'s. But that leads to a combinatorial explosion about which arguments are and which are not the same. *) | |- ?R (?f ?x) (?f _) => - apply (_ : Proper (_ ==> R) f); f_equiv + apply (_ : Proper (_ ==> R) f) | |- ?R (?f ?x ?y) (?f _ _) => - apply (_ : Proper (_ ==> _ ==> R) f); f_equiv + apply (_ : Proper (_ ==> _ ==> R) f) (* In case the function symbol differs, but the arguments are the same, maybe we have a pointwise_relation in our context. *) | H : pointwise_relation _ ?R ?f ?g |- ?R (?f ?x) (?g ?x) => - apply H; f_equiv + apply H end. +(** auto_proper solves goals of the form "f _ = f _", for any relation and any + number of arguments, by repeatedly apply f_equiv and handling trivial cases. + If it cannot solve an equality, it will leave that to the user. *) +Ltac auto_proper := + (* Deal with "pointwise_relation" *) + repeat lazymatch goal with + | |- pointwise_relation _ _ _ _ => intros ? + end; + (* Normalize away equalities. *) + simplify_eq; + (* repeatedly apply congruence lemmas and use the equalities in the hypotheses. *) + try (f_equiv; assumption || (symmetry; assumption) || auto_proper). + (** solve_proper solves goals of the form "Proper (R1 ==> R2)", for any number of relations. All the actual work is done by f_equiv; solve_proper just introduces the assumptions and unfolds the first @@ -291,7 +297,7 @@ Ltac solve_proper := | |- ?R (?f _ _) (?f _ _) => unfold f | |- ?R (?f _) (?f _) => unfold f end; - solve [ f_equiv ]. + solve [ auto_proper ]. (** The tactic [intros_revert tac] introduces all foralls/arrows, performs tac, and then reverts them. *)