1 (*********************************************************************************************************************************)
2 (* General: general data structures *)
3 (*********************************************************************************************************************************)
5 Require Import Coq.Unicode.Utf8.
6 Require Import Coq.Classes.RelationClasses.
7 Require Import Coq.Classes.Morphisms.
8 Require Import Coq.Setoids.Setoid.
9 Require Import Coq.Strings.String.
11 Require Import Coq.Lists.List.
12 Require Import Preamble.
13 Generalizable All Variables.
16 Definition EqDecider T := forall (n1 n2:T), sumbool (n1=n2) (not (n1=n2)).
17 Class EqDecidable (T:Type) :=
19 ; eqd_dec : forall v1 v2:T, sumbool (v1=v2) (not (v1=v2))
21 Coercion eqd_type : EqDecidable >-> Sortclass.
24 Class ToString (T:Type) := { toString : T -> string }.
25 Instance StringToString : ToString string := { toString := fun x => x }.
26 Notation "a +++ b" := (append (toString a) (toString b)) (at level 100).
28 (*******************************************************************************)
31 Inductive Tree (a:Type) : Type :=
32 | T_Leaf : a -> Tree a
33 | T_Branch : Tree a -> Tree a -> Tree a.
34 Implicit Arguments T_Leaf [ a ].
35 Implicit Arguments T_Branch [ a ].
37 Notation "a ,, b" := (@T_Branch _ a b) : tree_scope.
39 (* tree-of-option-of-X comes up a lot, so we give it special notations *)
40 Notation "[ q ]" := (@T_Leaf (option _) (Some q)) : tree_scope.
41 Notation "[ ]" := (@T_Leaf (option _) None) : tree_scope.
42 Notation "[]" := (@T_Leaf (option _) None) : tree_scope.
44 Fixpoint InT {A} (a:A) (t:Tree ??A) {struct t} : Prop :=
46 | T_Leaf None => False
47 | T_Leaf (Some x) => x = a
48 | T_Branch b1 b2 => InT a b1 \/ InT a b2
51 Open Scope tree_scope.
53 Fixpoint mapTree {a b:Type}(f:a->b)(t:@Tree a) : @Tree b :=
55 | T_Leaf x => T_Leaf (f x)
56 | T_Branch l r => T_Branch (mapTree f l) (mapTree f r)
58 Fixpoint mapOptionTree {a b:Type}(f:a->b)(t:@Tree ??a) : @Tree ??b :=
60 | T_Leaf None => T_Leaf None
61 | T_Leaf (Some x) => T_Leaf (Some (f x))
62 | T_Branch l r => T_Branch (mapOptionTree f l) (mapOptionTree f r)
64 Fixpoint mapTreeAndFlatten {a b:Type}(f:a->@Tree b)(t:@Tree a) : @Tree b :=
67 | T_Branch l r => T_Branch (mapTreeAndFlatten f l) (mapTreeAndFlatten f r)
69 Fixpoint mapOptionTreeAndFlatten {a b:Type}(f:a->@Tree ??b)(t:@Tree ??a) : @Tree ??b :=
72 | T_Leaf (Some x) => f x
73 | T_Branch l r => T_Branch (mapOptionTreeAndFlatten f l) (mapOptionTreeAndFlatten f r)
75 Fixpoint treeReduce {T:Type}{R:Type}(mapLeaf:T->R)(mergeBranches:R->R->R) (t:Tree T) :=
77 | T_Leaf x => mapLeaf x
78 | T_Branch y z => mergeBranches (treeReduce mapLeaf mergeBranches y) (treeReduce mapLeaf mergeBranches z)
80 Definition treeDecomposition {D T:Type} (mapLeaf:T->D) (mergeBranches:D->D->D) :=
81 forall d:D, { tt:Tree T & d = treeReduce mapLeaf mergeBranches tt }.
84 forall {Q}(t1 t2:Tree ??Q),
85 (forall q1 q2:Q, sumbool (q1=q2) (not (q1=q2))) ->
86 sumbool (t1=t2) (not (t1=t2)).
91 destruct a; destruct t2.
96 right; unfold not; intro; apply H. inversion H0; subst. auto.
97 right. unfold not; intro; inversion H.
98 right. unfold not; intro; inversion H.
100 right. unfold not; intro; inversion H.
102 right. unfold not; intro; inversion H.
105 right. unfold not; intro; inversion H.
106 set (IHt1_1 t2_1 X) as X1.
107 set (IHt1_2 t2_2 X) as X2.
108 destruct X1; destruct X2; subst.
127 Lemma mapOptionTree_compose : forall A B C (f:A->B)(g:B->C)(l:Tree ??A),
128 (mapOptionTree (g ○ f) l) = (mapOptionTree g (mapOptionTree f l)).
139 Lemma mapOptionTree_extensional {A}{B}(f g:A->B) : (forall a, f a = g a) -> (forall t, mapOptionTree f t = mapOptionTree g t).
143 simpl; rewrite H; auto.
144 simpl; rewrite IHt1; rewrite IHt2; auto.
147 Open Scope string_scope.
148 Fixpoint treeToString {T}{TT:ToString T}(t:Tree ??T) : string :=
150 | T_Leaf None => "[]"
151 | T_Leaf (Some s) => "["+++s+++"]"
152 | T_Branch b1 b2 => treeToString b1 +++ ",," +++ treeToString b2
154 Instance TreeToString {T}{TT:ToString T} : ToString (Tree ??T) := { toString := treeToString }.
156 (*******************************************************************************)
159 Notation "a :: b" := (cons a b) : list_scope.
160 Open Scope list_scope.
161 Fixpoint leaves {a:Type}(t:Tree (option a)) : list a :=
163 | (T_Leaf l) => match l with
167 | (T_Branch l r) => app (leaves l) (leaves r)
169 (* weak inverse of "leaves" *)
170 Fixpoint unleaves {A:Type}(l:list A) : Tree (option A) :=
173 | (a::b) => [a],,(unleaves b)
176 (* a map over a list and the conjunction of the results *)
177 Fixpoint mapProp {A:Type} (f:A->Prop) (l:list A) : Prop :=
180 | (a::al) => f a /\ mapProp f al
183 Lemma map_id : forall A (l:list A), (map (fun x:A => x) l) = l.
190 Lemma map_app : forall `(f:A->B) l l', map f (app l l') = app (map f l) (map f l').
197 Lemma map_compose : forall A B C (f:A->B)(g:B->C)(l:list A),
198 (map (g ○ f) l) = (map g (map f l)).
206 Lemma list_cannot_be_longer_than_itself : forall `(a:A)(b:list A), b = (a::b) -> False.
210 inversion H. apply IHb in H2.
213 Lemma list_cannot_be_longer_than_itself' : forall A (b:list A) (a c:A), b = (a::c::b) -> False.
222 Lemma mapOptionTree_on_nil : forall `(f:A->B) h, [] = mapOptionTree f h -> h=[].
225 destruct o. inversion H.
230 Lemma mapOptionTree_comp a b c (f:a->b) (g:b->c) q : (mapOptionTree g (mapOptionTree f q)) = mapOptionTree (g ○ f) q.
241 Lemma leaves_unleaves {T}(t:list T) : leaves (unleaves t) = t.
247 Lemma mapleaves' {T:Type}(t:list T){Q}{f:T->Q} : unleaves (map f t) = mapOptionTree f (unleaves t).
248 induction t; simpl in *; auto.
252 (* handy facts: map preserves the length of a list *)
253 Lemma map_on_nil : forall A B (s1:list A) (f:A->B), nil = map f s1 -> s1=nil.
262 Lemma map_on_singleton : forall A B (f:A->B) x (s1:list A), (cons x nil) = map f s1 -> { y : A & s1=(cons y nil) & (f y)=x }.
265 simpl in H; assert False. inversion H. inversion H0.
271 inversion H. apply map_on_nil in H2. auto.
275 inversion H. apply map_on_nil in H2. auto.
281 Lemma map_on_doubleton : forall A B (f:A->B) x y (s1:list A), ((x::y::nil) = map f s1) ->
282 { z : A*A & s1=((fst z)::(snd z)::nil) & (f (fst z))=x /\ (f (snd z))=y }.
296 Lemma mapTree_compose : forall A B C (f:A->B)(g:B->C)(l:Tree A),
297 (mapTree (g ○ f) l) = (mapTree g (mapTree f l)).
306 Lemma lmap_compose : forall A B C (f:A->B)(g:B->C)(l:list A),
307 (map (g ○ f) l) = (map g (map f l)).
316 (* sends a::b::c::nil to [[[[],,c],,b],,a] *)
317 Fixpoint unleaves' {A:Type}(l:list A) : Tree (option A) :=
320 | (a::b) => (unleaves' b),,[a]
323 (* sends a::b::c::nil to [[[[],,c],,b],,a] *)
324 Fixpoint unleaves'' {A:Type}(l:list ??A) : Tree ??A :=
327 | (a::b) => (unleaves'' b),,(T_Leaf a)
330 Lemma mapleaves {T:Type}(t:Tree ??T){Q}{f:T->Q} : leaves (mapOptionTree f t) = map f (leaves t).
340 Fixpoint filter {T:Type}(l:list ??T) : list T :=
343 | (None::b) => filter b
344 | ((Some x)::b) => x::(filter b)
347 Inductive distinct {T:Type} : list T -> Prop :=
348 | distinct_nil : distinct nil
349 | distinct_cons : forall a ax, (@In _ a ax -> False) -> distinct ax -> distinct (a::ax).
351 Inductive distinctT {T:Type} : Tree ??T -> Prop :=
352 | distinctT_nil : distinctT []
353 | distinctT_leaf : forall t, distinctT [t]
354 | distinctT_cons : forall t1 t2, (forall v, InT v t1 -> InT v t2 -> False) -> distinctT (t1,,t2).
356 Lemma in_decidable {VV:Type}{eqdVV:EqDecidable VV} : forall (v:VV)(lv:list VV), sumbool (In v lv) (not (In v lv)).
367 set (eqd_dec v a) as dec.
380 Lemma distinct_decidable {VV:Type}{eqdVV:EqDecidable VV} : forall (lv:list VV), sumbool (distinct lv) (not (distinct lv)).
383 left; apply distinct_nil.
385 set (in_decidable a lv) as dec.
387 right; unfold not; intros.
392 apply distinct_cons; auto.
400 Lemma distinctT_decidable {VV:Type}{eqdVV:EqDecidable VV} : forall (lv:Tree ??VV), sumbool (distinctT lv) (not (distinctT lv)).
404 Lemma map_preserves_length {A}{B}(f:A->B)(l:list A) : (length l) = (length (map f l)).
410 (* decidable quality on a list of elements which have decidable equality *)
411 Definition list_eq_dec : forall {T:Type}(l1 l2:list T)(dec:forall t1 t2:T, sumbool (eq t1 t2) (not (eq t1 t2))),
412 sumbool (eq l1 l2) (not (eq l1 l2)).
415 induction l1; intros.
418 right; intro H; inversion H.
419 destruct l2 as [| b l2].
420 right; intro H; inversion H.
421 set (IHl1 l2 dec) as eqx.
424 set (dec a b) as eqy.
428 right. intro. inversion H. subst. apply n. auto.
436 Instance EqDecidableList {T:Type}(eqd:EqDecidable T) : EqDecidable (list T).
437 apply Build_EqDecidable.
443 (*******************************************************************************)
444 (* Length-Indexed Lists *)
446 Inductive vec (A:Type) : nat -> Type :=
448 | vec_cons : forall n, A -> vec A n -> vec A (S n).
450 Fixpoint vec2list {n:nat}{t:Type}(v:vec t n) : list t :=
453 | vec_cons n a va => a::(vec2list va)
456 Require Import Omega.
457 Definition vec_get : forall {T:Type}{l:nat}(v:vec T l)(n:nat)(pf:lt n l), T.
472 Definition vec_zip {n:nat}{A B:Type}(va:vec A n)(vb:vec B n) : vec (A*B) n.
477 apply vec_cons; auto.
480 Definition vec_map {n:nat}{A B:Type}(f:A->B)(v:vec A n) : vec B n.
484 apply vec_cons; auto.
487 Fixpoint vec_In {A:Type} {n:nat} (a:A) (l:vec A n) : Prop :=
490 | vec_cons _ n m => (n = a) \/ vec_In a m
492 Implicit Arguments vec_nil [ A ].
493 Implicit Arguments vec_cons [ A n ].
495 Definition append_vec {n:nat}{T:Type}(v:vec T n)(t:T) : vec T (S n).
497 apply (vec_cons t vec_nil).
498 apply vec_cons; auto.
501 Definition list2vec {T:Type}(l:list T) : vec T (length l).
504 apply vec_cons; auto.
507 Definition vec_head {n:nat}{T}(v:vec T (S n)) : T.
510 Definition vec_tail {n:nat}{T}(v:vec T (S n)) : vec T n.
514 Lemma vec_chop {T}{l1 l2:list T}{Q}(v:vec Q (length (app l1 l2))) : vec Q (length l1).
519 inversion v; subst; auto.
521 inversion v; subst; auto.
524 Lemma vec_chop' {T}{l1 l2:list T}{Q}(v:vec Q (length (app l1 l2))) : vec Q (length l2).
528 apply IHl1; clear IHl1.
529 inversion v; subst; auto.
532 Lemma vec2list_len {T}{n}(v:vec T n) : length (vec2list v) = n.
538 Lemma vec2list_map_list2vec {A B}{n}(f:A->B)(v:vec A n) : map f (vec2list v) = vec2list (vec_map f v).
544 Lemma vec2list_list2vec {A}(v:list A) : vec2list (list2vec v) = v.
546 set (vec2list (list2vec (a :: v))) as q.
554 Notation "a ::: b" := (@vec_cons _ _ a b) (at level 20).
558 (*******************************************************************************)
561 (* a ShapedTree is a tree indexed by the shape (but not the leaf values) of another tree; isomorphic to (ITree (fun _ => Q)) *)
562 Inductive ShapedTree {T:Type}(Q:Type) : Tree ??T -> Type :=
563 | st_nil : @ShapedTree T Q []
564 | st_leaf : forall {t}, Q -> @ShapedTree T Q [t]
565 | st_branch : forall {t1}{t2}, @ShapedTree T Q t1 -> @ShapedTree T Q t2 -> @ShapedTree T Q (t1,,t2).
567 Fixpoint unshape {T:Type}{Q:Type}{idx:Tree ??T}(st:@ShapedTree T Q idx) : Tree ??Q :=
571 | st_branch _ _ b1 b2 => (unshape b1),,(unshape b2)
574 Definition mapShapedTree {T}{idx:Tree ??T}{V}{Q}(f:V->Q)(st:ShapedTree V idx) : ShapedTree Q idx.
577 apply st_leaf. apply f. apply q.
578 apply st_branch; auto.
581 Definition zip_shapedTrees {T:Type}{Q1 Q2:Type}{idx:Tree ??T}
582 (st1:ShapedTree Q1 idx)(st2:ShapedTree Q2 idx) : ShapedTree (Q1*Q2) idx.
590 apply st_branch; auto.
591 inversion st1; subst; apply IHidx1; auto.
592 inversion st2; subst; auto.
593 inversion st2; subst; apply IHidx2; auto.
594 inversion st1; subst; auto.
597 Definition build_shapedTree {T:Type}(idx:Tree ??T){Q:Type}(f:T->Q) : ShapedTree Q idx.
602 apply st_branch; auto.
605 Lemma unshape_map : forall {Q}{b}(f:Q->b){T}{idx:Tree ??T}(t:ShapedTree Q idx),
606 mapOptionTree f (unshape t) = unshape (mapShapedTree f t).
618 (*******************************************************************************)
619 (* Type-Indexed Lists *)
621 (* an indexed list *)
622 Inductive IList (I:Type)(F:I->Type) : list I -> Type :=
623 | INil : IList I F nil
624 | ICons : forall i is, F i -> IList I F is -> IList I F (i::is).
625 Implicit Arguments INil [ I F ].
626 Implicit Arguments ICons [ I F ].
628 Notation "a :::: b" := (@ICons _ _ _ _ a b) (at level 20).
630 Definition ilist_head {T}{F}{x}{y} : IList T F (x::y) -> F x.
637 Definition ilist_tail {T}{F}{x}{y} : IList T F (x::y) -> IList T F y.
644 Definition ilmap {I}{F}{G}{il:list I}(f:forall i:I, F i -> G i) : IList I F il -> IList I G il.
645 induction il; intros; auto.
651 Lemma ilist_chop {T}{F}{l1 l2:list T}(v:IList T F (app l1 l2)) : IList T F l1.
660 Lemma ilist_chop' {T}{F}{l1 l2:list T}(v:IList T F (app l1 l2)) : IList T F l2.
663 inversion v; subst; auto.
666 Fixpoint ilist_to_list {T}{Z}{l:list T}(il:IList T (fun _ => Z) l) : list Z :=
669 | a::::b => a::(ilist_to_list b)
672 (* a tree indexed by a (Tree (option X)) *)
673 Inductive ITree (I:Type)(F:I->Type) : Tree ??I -> Type :=
674 | INone : ITree I F []
675 | ILeaf : forall i: I, F i -> ITree I F [i]
676 | IBranch : forall it1 it2:Tree ??I, ITree I F it1 -> ITree I F it2 -> ITree I F (it1,,it2).
677 Implicit Arguments INil [ I F ].
678 Implicit Arguments ILeaf [ I F ].
679 Implicit Arguments IBranch [ I F ].
681 Definition itmap {I}{F}{G}{il:Tree ??I}(f:forall i:I, F i -> G i) : ITree I F il -> ITree I G il.
682 induction il; intros; auto.
688 apply IBranch; inversion X; auto.
691 Fixpoint itree_to_tree {T}{Z}{l:Tree ??T}(il:ITree T (fun _ => Z) l) : Tree ??Z :=
695 | IBranch _ _ b1 b2 => (itree_to_tree b1),,(itree_to_tree b2)
699 (*******************************************************************************)
700 (* Extensional equality on functions *)
702 Definition extensionality := fun (t1 t2:Type) => (fun (f:t1->t2) g => forall x:t1, (f x)=(g x)).
703 Hint Transparent extensionality.
704 Instance extensionality_Equivalence : forall t1 t2, Equivalence (extensionality t1 t2).
705 intros; apply Build_Equivalence;
706 intros; compute; intros; auto.
707 rewrite H; rewrite H0; auto.
709 Add Parametric Morphism (A B C:Type) : (fun f g => g ○ f)
710 with signature (extensionality A B ==> extensionality B C ==> extensionality A C) as parametric_morphism_extensionality.
711 unfold extensionality; intros; rewrite (H x1); rewrite (H0 (y x1)); auto.
713 Lemma extensionality_composes : forall t1 t2 t3 (f f':t1->t2) (g g':t2->t3),
714 (extensionality _ _ f f') ->
715 (extensionality _ _ g g') ->
716 (extensionality _ _ (g ○ f) (g' ○ f')).
718 unfold extensionality.
719 unfold extensionality in H.
720 unfold extensionality in H0.
731 CoInductive Fresh A T :=
732 { next : forall a:A, (T a * Fresh A T)
733 ; split : Fresh A T * Fresh A T
740 Definition map2 {A}{B}(f:A->B)(t:A*A) : (B*B) := ((f (fst t)), (f (snd t))).
744 Variable eol : string.
745 Extract Constant eol => "'\n':[]".
747 Class Monad {T:Type->Type} :=
748 { returnM : forall {a}, a -> T a
749 ; bindM : forall {a}{b}, T a -> (a -> T b) -> T b
751 Implicit Arguments Monad [ ].
752 Notation "a >>>= b" := (@bindM _ _ _ _ a b) (at level 50, left associativity).
754 (* the Error monad *)
755 Inductive OrError (T:Type) :=
756 | Error : forall error_message:string, OrError T
757 | OK : T -> OrError T.
758 Notation "??? T" := (OrError T) (at level 10).
759 Implicit Arguments Error [T].
760 Implicit Arguments OK [T].
762 Definition orErrorBind {T:Type} (oe:OrError T) {Q:Type} (f:T -> OrError Q) :=
767 Notation "a >>= b" := (@orErrorBind _ a _ b) (at level 20).
769 Open Scope string_scope.
770 Definition orErrorBindWithMessage {T:Type} (oe:OrError T) {Q:Type} (f:T -> OrError Q) err_msg :=
772 | Error s => Error (err_msg +++ eol +++ " " +++ s)
776 Notation "a >>=[ S ] b" := (@orErrorBindWithMessage _ a _ b S) (at level 20).
778 Definition addErrorMessage s {T} (x:OrError T) :=
779 x >>=[ s ] (fun y => OK y).
781 Inductive Indexed {T:Type}(f:T -> Type) : ???T -> Type :=
782 | Indexed_Error : forall error_message:string, Indexed f (Error error_message)
783 | Indexed_OK : forall t, f t -> Indexed f (OK t)
787 Require Import Coq.Arith.EqNat.
788 Instance EqDecidableNat : EqDecidable nat.
789 apply Build_EqDecidable.
794 (* for a type with decidable equality, we can maintain lists of distinct elements *)
795 Section DistinctList.
796 Context `{V:EqDecidable}.
798 Fixpoint addToDistinctList (cv:V)(cvl:list V) :=
801 | cv'::cvl' => if eqd_dec cv cv' then cvl' else cv'::(addToDistinctList cv cvl')
804 Fixpoint removeFromDistinctList (cv:V)(cvl:list V) :=
807 | cv'::cvl' => if eqd_dec cv cv' then removeFromDistinctList cv cvl' else cv'::(removeFromDistinctList cv cvl')
810 Fixpoint removeFromDistinctList' (cvrem:list V)(cvl:list V) :=
813 | rem::cvrem' => removeFromDistinctList rem (removeFromDistinctList' cvrem' cvl)
816 Fixpoint mergeDistinctLists (cvl1:list V)(cvl2:list V) :=
819 | cv'::cvl' => mergeDistinctLists cvl' (addToDistinctList cv' cvl2)
823 Lemma list2vecOrFail {T}(l:list T)(n:nat)(error_message:nat->nat->string) : ???(vec T n).
824 set (list2vec l) as v.
825 destruct (eqd_dec (length l) n).
826 rewrite e in v; apply OK; apply v.
827 apply (Error (error_message (length l) n)).
831 Variable UniqSupply : Type. Extract Inlined Constant UniqSupply => "UniqSupply.UniqSupply".
832 Variable Unique : Type. Extract Inlined Constant Unique => "Unique.Unique".
833 Variable uniqFromSupply : UniqSupply -> Unique. Extract Inlined Constant uniqFromSupply => "UniqSupply.uniqFromSupply".
834 Variable splitUniqSupply : UniqSupply -> UniqSupply * UniqSupply.
835 Extract Inlined Constant splitUniqSupply => "UniqSupply.splitUniqSupply".
836 Variable unique_eq : forall u1 u2:Unique, sumbool (u1=u2) (u1≠u2).
837 Extract Inlined Constant unique_eq => "(==)".
838 Variable unique_toString : Unique -> string.
839 Extract Inlined Constant unique_toString => "show".
840 Instance EqDecidableUnique : EqDecidable Unique :=
841 { eqd_dec := unique_eq }.
842 Instance EqDecidableToString : ToString Unique :=
843 { toString := unique_toString }.
845 Inductive UniqM {T:Type} : Type :=
846 | uniqM : (UniqSupply -> ???(UniqSupply * T)) -> UniqM.
847 Implicit Arguments UniqM [ ].
849 Instance UniqMonad : Monad UniqM :=
850 { returnM := fun T (x:T) => uniqM (fun u => OK (u,x))
851 ; bindM := fun a b (x:UniqM a) (f:a->UniqM b) =>
857 | OK (u',va) => match f va with
864 Definition getU : UniqM Unique :=
865 uniqM (fun us => let (us1,us2) := splitUniqSupply us in OK (us1,(uniqFromSupply us2))).
867 Notation "'bind' x = e ; f" := (@bindM _ _ _ _ e (fun x => f)) (x ident, at level 60, right associativity).
868 Notation "'return' x" := (returnM x) (at level 100).
869 Notation "'failM' x" := (uniqM (fun _ => Error x)) (at level 100).
876 Record FreshMonad {T:Type} :=
878 ; FMT_Monad :> Monad FMT
879 ; FMT_fresh : forall tl:list T, FMT { t:T & @In _ t tl -> False }
881 Implicit Arguments FreshMonad [ ].
882 Coercion FMT : FreshMonad >-> Funclass.
886 Variable Prelude_error : forall {A}, string -> A. Extract Inlined Constant Prelude_error => "Prelude.error".
891 Ltac eqd_dec_refl X :=
892 destruct (eqd_dec X X) as [eqd_dec1 | eqd_dec2];
893 [ clear eqd_dec1 | set (eqd_dec2 (refl_equal _)) as eqd_dec2'; inversion eqd_dec2' ].
895 Lemma unleaves_injective : forall T (t1 t2:list T), unleaves t1 = unleaves t2 -> t1 = t2.
897 induction t1; intros.
905 set (IHt1 _ H2) as q.
910 Lemma fst_zip : forall T Q n (v1:vec T n)(v2:vec Q n), vec_map (@fst _ _) (vec_zip v1 v2) = v1.
914 Lemma snd_zip : forall T Q n (v1:vec T n)(v2:vec Q n), vec_map (@snd _ _) (vec_zip v1 v2) = v2.