(* Copyright (c) 2012-2013, Robbert Krebbers. *) (* This file is distributed under the terms of the BSD license. *) (** This files extends the implementation of finite over [positive] to finite maps whose keys range over Coq's data type of binary naturals [N]. *) Require Import pmap. Require Export prelude fin_maps. Local Open Scope N_scope. Record Nmap A := NMap { Nmap_0 : option A; Nmap_pos : Pmap A }. Arguments Nmap_0 {_} _. Arguments Nmap_pos {_} _. Arguments NMap {_} _ _. Instance Nmap_eq_dec `{∀ x y : A, Decision (x = y)} (t1 t2 : Nmap A) : Decision (t1 = t2). Proof. refine match t1, t2 with | NMap x t1, NMap y t2 => cast_if_and (decide (x = y)) (decide (t1 = t2)) end; abstract congruence. Defined. Instance Nempty {A} : Empty (Nmap A) := NMap None ∅. Instance Nlookup {A} : Lookup N A (Nmap A) := λ i t, match i with | N0 => Nmap_0 t | Npos p => Nmap_pos t !! p end. Instance Npartial_alter {A} : PartialAlter N A (Nmap A) := λ f i t, match i, t with | N0, NMap o t => NMap (f o) t | Npos p, NMap o t => NMap o (partial_alter f p t) end. Instance Nto_list {A} : FinMapToList N A (Nmap A) := λ t, match t with | NMap o t => option_case (λ x, [(0,x)]) [] o ++ (fst_map Npos <\$> map_to_list t) end. Instance Nmerge: Merge Nmap := λ A B C f t1 t2, match t1, t2 with | NMap o1 t1, NMap o2 t2 => NMap (f o1 o2) (merge f t1 t2) end. Instance Nfmap: FMap Nmap := λ A B f t, match t with | NMap o t => NMap (fmap f o) (fmap f t) end. Instance: FinMap N Nmap. Proof. split. * intros ? [??] [??] H. f_equal. + apply (H 0). + apply map_eq. intros i. apply (H (Npos i)). * by intros ? [|?]. * intros ? f [? t] [|i]; simpl. + done. + apply lookup_partial_alter. * intros ? f [? t] [|i] [|j]; simpl; try intuition congruence. intros. apply lookup_partial_alter_ne. congruence. * intros ??? [??] []; simpl. done. apply lookup_fmap. * intros ? [[x|] t]; unfold map_to_list; simpl. + constructor. - rewrite elem_of_list_fmap. by intros [[??] [??]]. - rewrite (NoDup_fmap _). apply map_to_list_nodup. + rewrite (NoDup_fmap _). apply map_to_list_nodup. * intros ? t i x. unfold map_to_list. split. + destruct t as [[y|] t]; simpl. - rewrite elem_of_cons, elem_of_list_fmap. intros [? | [[??] [??]]]; simplify_equality; simpl; [done |]. by apply elem_of_map_to_list. - rewrite elem_of_list_fmap. intros [[??] [??]]; simplify_equality; simpl. by apply elem_of_map_to_list. + destruct t as [[y|] t]; simpl. - rewrite elem_of_cons, elem_of_list_fmap. destruct i as [|i]; simpl; [intuition congruence |]. intros. right. exists (i, x). by rewrite elem_of_map_to_list. - rewrite elem_of_list_fmap. destruct i as [|i]; simpl; [done |]. intros. exists (i, x). by rewrite elem_of_map_to_list. * intros ??? f ? [o1 t1] [o2 t2] [|?]; simpl. + done. + apply (lookup_merge f t1 t2). Qed.