(* Copyright (c) 2012, Robbert Krebbers. *) (* This file is distributed under the terms of the BSD license. *) (** This file collects some general purpose tactics that are used throughout the development. *) Require Export Psatz. Require Export base. (** We declare hint databases [f_equal], [congruence] and [lia] and containing solely the tactic corresponding to its name. These hint database are useful in to be combined in combination with other hint database. *) Hint Extern 998 (_ = _) => f_equal : f_equal. Hint Extern 999 => congruence : congruence. Hint Extern 1000 => lia : lia. (** The tactic [intuition] expands to [intuition auto with *] by default. This is rather efficient when having big hint databases, or expensive [Hint Extern] declarations as the above. *) Tactic Notation "intuition" := intuition auto. (** A slightly modified version of Ssreflect's finishing tactic [done]. It also performs [reflexivity] and does not compute the goal's [hnf] so as to avoid unfolding setoid equalities. Note that this tactic performs much better than Coq's [easy] as it does not perform [inversion]. *) Ltac done := trivial; intros; solve [ repeat first [ solve [trivial] | solve [symmetry; trivial] | reflexivity | discriminate | contradiction | split ] | match goal with H : ¬_ |- _ => solve [destruct H; trivial] end ]. Tactic Notation "by" tactic(tac) := tac; done. Ltac case_match := match goal with | H : context [ match ?x with _ => _ end ] |- _ => destruct x eqn:? | |- context [ match ?x with _ => _ end ] => destruct x eqn:? end. (** The tactic [clear dependent H1 ... Hn] clears the hypotheses [Hi] and their dependencies. *) Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) := clear dependent H1; clear dependent H2. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) := clear dependent H1 H2; clear dependent H3. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) := clear dependent H1 H2 H3; clear dependent H4. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) := clear dependent H1 H2 H3 H4; clear dependent H5. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) hyp (H6) := clear dependent H1 H2 H3 H4 H5; clear dependent H6. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) hyp (H6) hyp(H7) := clear dependent H1 H2 H3 H4 H5 H6; clear dependent H7. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) hyp (H6) hyp(H7) hyp(H8) := clear dependent H1 H2 H3 H4 H5 H6 H7; clear dependent H8. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) hyp (H6) hyp(H7) hyp(H8) hyp(H9) := clear dependent H1 H2 H3 H4 H5 H6 H7 H8; clear dependent H9. Tactic Notation "clear" "dependent" hyp(H1) hyp(H2) hyp(H3) hyp(H4) hyp(H5) hyp (H6) hyp(H7) hyp(H8) hyp(H9) hyp(H10) := clear dependent H1 H2 H3 H4 H5 H6 H7 H8 H9; clear dependent H10. (** The tactic [first_of tac1 tac2] calls [tac1] and then calls [tac2] on the first subgoal generated by [tac1] *) Tactic Notation "first_of" tactic3(tac1) "by" tactic3(tac2) := (tac1; [ tac2 ]) || (tac1; [ tac2 |]) || (tac1; [ tac2 | | ]) || (tac1; [ tac2 | | | ]) || (tac1; [ tac2 | | | | ]) || (tac1; [ tac2 | | | | | ]) || (tac1; [ tac2 | | | | | |]) || (tac1; [ tac2 | | | | | | |]) || (tac1; [ tac2 | | | | | | | |]) || (tac1; [ tac2 | | | | | | | | |]) || (tac1; [ tac2 | | | | | | | | | |]) || (tac1; [ tac2 | | | | | | | | | | |]) || (tac1; [ tac2 | | | | | | | | | | | |]). (** The tactic [is_non_dependent H] determines whether the goal's conclusion or assumptions depend on [H]. *) Tactic Notation "is_non_dependent" constr(H) := match goal with | _ : context [ H ] |- _ => fail 1 | |- context [ H ] => fail 1 | _ => idtac end. (* The tactic [var_eq x y] fails if [x] and [y] are unequal. *) Ltac var_eq x1 x2 := match x1 with x2 => idtac | _ => fail 1 end. Ltac var_neq x1 x2 := match x1 with x2 => fail 1 | _ => idtac end. Tactic Notation "repeat_on_hyps" tactic3(tac) := repeat match goal with H : _ |- _ => progress tac H end. Ltac block_hyps := repeat_on_hyps (fun H => match type of H with | block _ => idtac | ?T => change (block T) in H end). Ltac unblock_hyps := unfold block in * |-. (** The tactic [injection' H] is a variant of injection that introduces the generated equalities. *) Ltac injection' H := block_goal; injection H; clear H; intros; unblock_goal. (** The tactic [simplify_equality] repeatedly substitutes, discriminates, and injects equalities, and tries to contradict impossible inequalities. *) Ltac simplify_equality := repeat match goal with | H : _ ≠ _ |- _ => by destruct H | H : _ = _ → False |- _ => by destruct H | H : ?x = _ |- _ => subst x | H : _ = ?x |- _ => subst x | H : _ = _ |- _ => discriminate H | H : ?f _ = ?f _ |- _ => apply (injective f) in H (* before [injection'] to circumvent bug #2939 in some situations *) | H : _ = _ |- _ => injection' H | H : ?x = ?x |- _ => clear H end. (** Coq's default [remember] tactic does have an option to name the generated equality. The following tactic extends [remember] to do so. *) Tactic Notation "remember" constr(t) "as" "(" ident(x) "," ident(E) ")" := remember t as x; match goal with | E' : x = _ |- _ => rename E' into E end. (** Given a tactic [tac2] generating a list of terms, [iter tac1 tac2] runs [tac x] for each element [x] until [tac x] succeeds. If it does not suceed for any element of the generated list, the whole tactic wil fail. *) Tactic Notation "iter" tactic(tac) tactic(l) := let rec go l := match l with | ?x :: ?l => tac x || go l end in go l. (** Given H : [A_1 → ... → A_n → B] (where each [A_i] is non-dependent), the tactic [feed tac H tac_by] creates a subgoal for each [A_i] and calls [tac p] with the generated proof [p] of [B]. *) Tactic Notation "feed" tactic(tac) constr(H) := let rec go H := let T := type of H in lazymatch eval hnf in T with | ?T1 → ?T2 => (* Use a separate counter for fresh names to make it more likely that the generated name is "fresh" with respect to those generated before calling the [feed] tactic. In particular, this hack makes sure that tactics like [let H' := fresh in feed (fun p => pose proof p as H') H] do not break. *) let HT1 := fresh "feed" in assert T1 as HT1; [| go (H HT1); clear HT1 ] | ?T1 => tac H end in go H. (** The tactic [efeed tac H] is similar to [feed], but it also instantiates dependent premises of [H] with evars. *) Tactic Notation "efeed" tactic(tac) constr(H) := let rec go H := let T := type of H in lazymatch eval hnf in T with | ?T1 → ?T2 => let HT1 := fresh "feed" in assert T1 as HT1; [| go (H HT1); clear HT1 ] | ?T1 → _ => let e := fresh "feed" in evar (e:T1); let e' := eval unfold e in e in clear e; go (H e') | ?T1 => tac H end in go H. (** The following variants of [pose proof], [specialize], [inversion], and [destruct], use the [feed] tactic before invoking the actual tactic. *) Tactic Notation "feed" "pose" "proof" constr(H) "as" ident(H') := feed (fun p => pose proof p as H') H. Tactic Notation "feed" "pose" "proof" constr(H) := feed (fun p => pose proof p) H. Tactic Notation "efeed" "pose" "proof" constr(H) "as" ident(H') := efeed (fun p => pose proof p as H') H. Tactic Notation "efeed" "pose" "proof" constr(H) := efeed (fun p => pose proof p) H. Tactic Notation "feed" "specialize" hyp(H) := feed (fun p => specialize p) H. Tactic Notation "efeed" "specialize" hyp(H) := efeed (fun p => specialize p) H. Tactic Notation "feed" "inversion" constr(H) := feed (fun p => let H':=fresh in pose proof p as H'; inversion H') H. Tactic Notation "feed" "inversion" constr(H) "as" simple_intropattern(IP) := feed (fun p => let H':=fresh in pose proof p as H'; inversion H' as IP) H. Tactic Notation "feed" "destruct" constr(H) := feed (fun p => let H':=fresh in pose proof p as H'; destruct H') H. Tactic Notation "feed" "destruct" constr(H) "as" simple_intropattern(IP) := feed (fun p => let H':=fresh in pose proof p as H'; destruct H' as IP) H. (** Coq's [firstorder] tactic fails or loops on rather small goals already. In particular, on those generated by the tactic [unfold_elem_ofs] to solve propositions on collections. The [naive_solver] tactic implements an ad-hoc and incomplete [firstorder]-like solver using Ltac's backtracking mechanism. The tactic suffers from the following limitations: - It might leave unresolved evars as Ltac provides no way to detect that. - To avoid the tactic going into pointless loops, it just does not allow a universally quantified hypothesis to be used more than once. - It does not perform backtracking on instantiation of universally quantified assumptions. Despite these limitations, it works much better than Coq's [firstorder] tactic for the purposes of this development. This tactic either fails or proves the goal. *) Tactic Notation "naive_solver" tactic(tac) := unfold iff, not in *; let rec go := repeat match goal with (**i intros *) | |- ∀ _, _ => intro (**i simplification of assumptions *) | H : False |- _ => destruct H | H : _ ∧ _ |- _ => destruct H | H : ∃ _, _ |- _ => destruct H (**i simplify and solve equalities *) | |- _ => progress simpl in * | |- _ => progress simplify_equality (**i solve the goal *) | |- _ => solve [ eassumption | symmetry; eassumption | reflexivity ] (**i operations that generate more subgoals *) | |- _ ∧ _ => split | H : _ ∨ _ |- _ => destruct H (**i solve the goal using the user supplied tactic *) | |- _ => solve [tac] end; (**i use recursion to enable backtracking on the following clauses *) match goal with (**i instantiations of assumptions *) | H : _ → _ |- _ => is_non_dependent H; eapply H; clear H; go | H : _ → _ |- _ => is_non_dependent H; (**i create subgoals for all premises *) efeed (fun p => match type of p with | _ ∧ _ => let H' := fresh in pose proof p as H'; destruct H' | ∃ _, _ => let H' := fresh in pose proof p as H'; destruct H' | _ ∨ _ => let H' := fresh in pose proof p as H'; destruct H' | False => let H' := fresh in pose proof p as H'; destruct H' end) H; (**i solve these subgoals, but clear [H] to avoid loops *) clear H; go (**i instantiation of the conclusion *) | |- ∃ x, _ => eexists; go | |- _ ∨ _ => first [left; go | right; go] end in go. Tactic Notation "naive_solver" := naive_solver eauto.