agda-spa/Map.agda

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open import Relation.Binary.PropositionalEquality as Eq using (_≡_; refl; sym; trans; cong)
open import Relation.Binary.Definitions using (Decidable)
open import Relation.Binary.Core using (Rel)
open import Relation.Nullary using (Dec; yes; no; Reflects; ofʸ; ofⁿ)
open import Agda.Primitive using (Level; _⊔_)
module Map {a b : Level} (A : Set a) (B : Set b)
(≡-dec-A : Decidable (_≡_ {a} {A}))
where
import Data.List.Membership.Propositional as MemProp
open import Relation.Nullary using (¬_)
open import Data.Nat using ()
open import Data.List using (List; map; []; _∷_; _++_)
open import Data.List.Relation.Unary.All using (All; []; _∷_)
open import Data.List.Relation.Unary.Any using (Any; here; there) -- TODO: re-export these with nicer names from map
open import Data.Product using (_×_; _,_; Σ; proj₁ ; proj₂)
open import Data.Empty using ()
keys : List (A × B) List A
keys = map proj₁
data Unique {c} {C : Set c} : List C Set c where
empty : Unique []
push : {x : C} {xs : List C}
All (λ x' ¬ x x') xs
Unique xs
Unique (x xs)
Unique-append : {c} {C : Set c} {x : C} {xs : List C}
¬ MemProp._∈_ x xs Unique xs Unique (xs ++ (x []))
Unique-append {c} {C} {x} {[]} _ _ = push [] empty
Unique-append {c} {C} {x} {x' xs'} x∉xs (push x'≢ uxs') =
push (help x'≢) (Unique-append (λ x∈xs' x∉xs (there x∈xs')) uxs')
where
x'≢x : ¬ x' x
x'≢x x'≡x = x∉xs (here (sym x'≡x))
help : {l : List C} All (λ x'' ¬ x' x'') l All (λ x'' ¬ x' x'') (l ++ (x []))
help {[]} _ = x'≢x []
help {e es} (x'≢e x'≢es) = x'≢e help x'≢es
All¬-¬Any : {p c} {C : Set c} {P : C Set p} {l : List C} All (λ x ¬ P x) l ¬ Any P l
All¬-¬Any {l = x xs} (¬Px _) (here Px) = ¬Px Px
All¬-¬Any {l = x xs} (_ ¬Pxs) (there Pxs) = All¬-¬Any ¬Pxs Pxs
absurd : {a} {A : Set a} A
absurd ()
private module _ where
open MemProp using (_∈_)
unique-not-in : {k : A} {v : B} {l : List (A × B)}
¬ (All (λ k' ¬ k k') (keys l) × (k , v) l)
unique-not-in {l = (k' , _) xs} (k≢k' _ , here k',≡x) =
k≢k' (cong proj₁ k',≡x)
unique-not-in {l = _ xs} (_ rest , there k,v'∈xs) =
unique-not-in (rest , k,v'∈xs)
ListAB-functional : {k : A} {v v' : B} {l : List (A × B)}
Unique (keys l) (k , v) l (k , v') l v v'
ListAB-functional _ (here k,v≡x) (here k,v'≡x) =
cong proj₂ (trans k,v≡x (sym k,v'≡x))
ListAB-functional (push k≢xs _) (here k,v≡x) (there k,v'∈xs)
rewrite sym k,v≡x = absurd (unique-not-in (k≢xs , k,v'∈xs))
ListAB-functional (push k≢xs _) (there k,v∈xs) (here k,v'≡x)
rewrite sym k,v'≡x = absurd (unique-not-in (k≢xs , k,v∈xs))
ListAB-functional {l = _ xs } (push _ uxs) (there k,v∈xs) (there k,v'∈xs) =
ListAB-functional uxs k,v∈xs k,v'∈xs
∈k-dec : (k : A) (l : List (A × B)) Dec (k keys l)
∈k-dec k [] = no (λ ())
∈k-dec k ((k' , v) xs)
with (≡-dec-A k k')
... | yes k≡k' = yes (here k≡k')
... | no k≢k' with (∈k-dec k xs)
... | yes k∈kxs = yes (there k∈kxs)
... | no k∉kxs = no witness
where
witness : ¬ k keys ((k' , v) xs)
witness (here k≡k') = k≢k' k≡k'
witness (there k∈kxs) = k∉kxs k∈kxs
∈-cong : {c d} {C : Set c} {D : Set d} {c : C} {l : List C}
(f : C D) c l f c map f l
∈-cong f (here c≡c') = here (cong f c≡c')
∈-cong f (there c∈xs) = there (∈-cong f c∈xs)
locate : {k : A} {l : List (A × B)} k keys l Σ B (λ v (k , v) l)
locate {k} {(k' , v) xs} (here k≡k') rewrite k≡k' = (v , here refl)
locate {k} {(k' , v) xs} (there k∈kxs) = let (v , k,v∈xs) = locate k∈kxs in (v , there k,v∈xs)
private module ImplRelation (_≈_ : B B Set b) where
open MemProp using (_∈_)
subset : List (A × B) List (A × B) Set (a b)
subset m₁ m₂ = (k : A) (v : B) (k , v) m₁
Σ B (λ v' v v' × ((k , v') m₂))
private module ImplInsert (f : B B B) where
open import Data.List using (map)
open MemProp using (_∈_)
private
_∈k_ : A List (A × B) Set a
_∈k_ k m = k (keys m)
foldr : {c} {C : Set c} (A B C C) -> C -> List (A × B) -> C
foldr f b [] = b
foldr f b ((k , v) xs) = f k v (foldr f b xs)
insert : A B List (A × B) List (A × B)
insert k v [] = (k , v) []
insert k v (x@(k' , v') xs) with ≡-dec-A k k'
... | yes _ = (k' , f v v') xs
... | no _ = x insert k v xs
merge : List (A × B) List (A × B) List (A × B)
merge m₁ m₂ = foldr insert m₂ m₁
insert-keys-∈ : {k : A} {v : B} {l : List (A × B)}
k ∈k l keys l keys (insert k v l)
insert-keys-∈ {k} {v} {(k' , v') xs} (here k≡k')
with (≡-dec-A k k')
... | yes _ = refl
... | no k≢k' = absurd (k≢k' k≡k')
insert-keys-∈ {k} {v} {(k' , _) xs} (there k∈kxs)
with (≡-dec-A k k')
... | yes _ = refl
... | no _ = cong (λ xs' k' xs') (insert-keys-∈ k∈kxs)
insert-keys-∉ : {k : A} {v : B} {l : List (A × B)}
¬ (k ∈k l) (keys l ++ (k [])) keys (insert k v l)
insert-keys-∉ {k} {v} {[]} _ = refl
insert-keys-∉ {k} {v} {(k' , v') xs} k∉kl
with (≡-dec-A k k')
... | yes k≡k' = absurd (k∉kl (here k≡k'))
... | no _ = cong (λ xs' k' xs')
(insert-keys-∉ (λ k∈kxs k∉kl (there k∈kxs)))
insert-preserves-Unique : {k : A} {v : B} {l : List (A × B)}
Unique (keys l) Unique (keys (insert k v l))
insert-preserves-Unique {k} {v} {l} u
with (∈k-dec k l)
... | yes k∈kl rewrite insert-keys-∈ {v = v} k∈kl = u
... | no k∉kl rewrite sym (insert-keys-∉ {v = v} k∉kl) = Unique-append k∉kl u
merge-preserves-Unique : (l₁ l₂ : List (A × B))
Unique (keys l₂) Unique (keys (merge l₁ l₂))
merge-preserves-Unique [] l₂ u₂ = u₂
merge-preserves-Unique ((k₁ , v₁) xs₁) l₂ u₂ =
insert-preserves-Unique (merge-preserves-Unique xs₁ l₂ u₂)
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insert-fresh : {k : A} {v : B} {l : List (A × B)}
¬ k ∈k l (k , v) insert k v l
insert-fresh {l = []} k∉kl = here refl
insert-fresh {k} {l = (k' , v') xs} k∉kl
with ≡-dec-A k k'
... | yes k≡k' = absurd (k∉kl (here k≡k'))
... | no _ = there (insert-fresh (λ k∈kxs k∉kl (there k∈kxs)))
insert-preserves-∉k : {k k' : A} {v' : B} {l : List (A × B)}
¬ k k' ¬ k ∈k l ¬ k ∈k insert k' v' l
insert-preserves-∉k {l = []} k≢k' k∉kl (here k≡k') = k≢k' k≡k'
insert-preserves-∉k {l = []} k≢k' k∉kl (there ())
insert-preserves-∉k {k} {k'} {v'} {(k'' , v'') xs} k≢k' k∉kl k∈kil
with ≡-dec-A k k''
... | yes k≡k'' = k∉kl (here k≡k'')
... | no k≢k'' with ≡-dec-A k' k'' | k∈kil
... | yes k'≡k'' | here k≡k'' = k≢k'' k≡k''
... | yes k'≡k'' | there k∈kxs = k∉kl (there k∈kxs)
... | no k'≢k'' | here k≡k'' = k∉kl (here k≡k'')
... | no k'≢k'' | there k∈kxs = insert-preserves-∉k k≢k'
(λ k∈kxs k∉kl (there k∈kxs)) k∈kxs
merge-preserves-∉ : {k : A} {l₁ l₂ : List (A × B)}
¬ k ∈k l₁ ¬ k ∈k l₂ ¬ k ∈k merge l₁ l₂
merge-preserves-∉ {l₁ = []} _ k∉kl₂ = k∉kl₂
merge-preserves-∉ {k} {(k' , v') xs₁} k∉kl₁ k∉kl₂
with ≡-dec-A k k'
... | yes k≡k' = absurd (k∉kl₁ (here k≡k'))
... | no k≢k' = insert-preserves-∉k k≢k' (merge-preserves-∉ (λ k∈kxs₁ k∉kl₁ (there k∈kxs₁)) k∉kl₂)
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insert-preserves-∈ : {k k' : A} {v v' : B} {l : List (A × B)}
¬ k k' (k , v) l (k , v) insert k' v' l
insert-preserves-∈ {k} {k'} {l = x xs} k≢k' (here k,v=x)
rewrite sym k,v=x with ≡-dec-A k' k
... | yes k'≡k = absurd (k≢k' (sym k'≡k))
... | no _ = here refl
insert-preserves-∈ {k} {k'} {l = (k'' , _) xs} k≢k' (there k,v∈xs)
with ≡-dec-A k' k''
... | yes _ = there k,v∈xs
... | no _ = there (insert-preserves-∈ k≢k' k,v∈xs)
insert-preserves-∈k : {k k' : A} {v' : B} {l : List (A × B)}
¬ k k' k ∈k l k ∈k insert k' v' l
insert-preserves-∈k k≢k' k∈kl =
let (v , k,v∈l) = locate k∈kl
in ∈-cong proj₁ (insert-preserves-∈ k≢k' k,v∈l)
merge-preserves-∈₁ : {k : A} {v : B} {l₁ l₂ : List (A × B)}
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¬ k ∈k l₁ (k , v) l₂ (k , v) merge l₁ l₂
merge-preserves-∈₁ {l₁ = []} _ k,v∈l₂ = k,v∈l₂
merge-preserves-∈₁ {l₁ = (k' , v') xs₁} k∉kl₁ k,v∈l₂ =
let recursion = merge-preserves-∈₁ (λ k∈xs₁ k∉kl₁ (there k∈xs₁)) k,v∈l₂
in insert-preserves-∈ (λ k≡k' k∉kl₁ (here k≡k')) recursion
merge-preserves-∈₂ : {k : A} {v : B} {l₁ l₂ : List (A × B)}
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Unique (keys l₁) (k , v) l₁ ¬ k ∈k l₂ (k , v) merge l₁ l₂
merge-preserves-∈₂ {k} {v} {(k' , v') xs₁} (push k'≢xs₁ uxs₁) (there k,v∈xs₁) k∉kl₂ =
insert-preserves-∈ k≢k' k,v∈mxs₁l
where
k,v∈mxs₁l = merge-preserves-∈₂ uxs₁ k,v∈xs₁ k∉kl₂
k≢k' : ¬ k k'
k≢k' with ≡-dec-A k k'
... | yes k≡k' rewrite k≡k' = absurd (All¬-¬Any k'≢xs₁ (∈-cong proj₁ k,v∈xs₁))
... | no k≢k' = k≢k'
merge-preserves-∈₂ {l₁ = (k' , v') xs₁} (push k'≢xs₁ uxs₁) (here k,v≡k',v') k∉kl₂
rewrite cong proj₁ k,v≡k',v' rewrite cong proj₂ k,v≡k',v' =
insert-fresh (merge-preserves-∉ (All¬-¬Any k'≢xs₁) k∉kl₂)
insert-combines : {k : A} {v v' : B} {l : List (A × B)}
Unique (keys l) (k , v') l (k , f v v') (insert k v l)
insert-combines {l = (k' , v'') xs} _ (here k,v'≡k',v'')
rewrite cong proj₁ k,v'≡k',v'' rewrite cong proj₂ k,v'≡k',v''
with ≡-dec-A k' k'
... | yes _ = here refl
... | no k≢k' = absurd (k≢k' refl)
insert-combines {k} {l = (k' , v'') xs} (push k'≢xs uxs) (there k,v'∈xs)
with ≡-dec-A k k'
... | yes k≡k' rewrite k≡k' = absurd (All¬-¬Any k'≢xs (∈-cong proj₁ k,v'∈xs))
... | no k≢k' = there (insert-combines uxs k,v'∈xs)
merge-combines : {k : A} {v₁ v₂ : B} {l₁ l₂ : List (A × B)}
Unique (keys l₁) Unique (keys l₂)
(k , v₁) l₁ (k , v₂) l₂ (k , f v₁ v₂) merge l₁ l₂
merge-combines {l₁ = (k' , v) xs₁} {l₂} (push k'≢xs₁ uxs₁) ul₂ (here k,v₁≡k',v) k,v₂∈l₂
rewrite cong proj₁ (sym (k,v₁≡k',v)) rewrite cong proj₂ (sym (k,v₁≡k',v)) =
insert-combines (merge-preserves-Unique xs₁ l₂ ul₂) (merge-preserves-∈₁ (All¬-¬Any k'≢xs₁) k,v₂∈l₂)
merge-combines {k} {l₁ = (k' , v) xs₁} (push k'≢xs₁ uxs₁) ul₂ (there k,v₁∈xs₁) k,v₂∈l₂ =
insert-preserves-∈ k≢k' (merge-combines uxs₁ ul₂ k,v₁∈xs₁ k,v₂∈l₂)
where
k≢k' : ¬ k k'
k≢k' with ≡-dec-A k k'
... | yes k≡k' rewrite k≡k' = absurd (All¬-¬Any k'≢xs₁ (∈-cong proj₁ k,v₁∈xs₁))
... | no k≢k' = k≢k'
Map : Set (a b)
Map = Σ (List (A × B)) (λ l Unique (keys l))
_∈_ : (A × B) Map Set (a b)
_∈_ p (kvs , _) = MemProp._∈_ p kvs
_∈k_ : A Map Set a
_∈k_ k (kvs , _) = MemProp._∈_ k (keys kvs)
Map-functional : {k : A} {v v' : B} {m : Map} (k , v) m (k , v') m v v'
Map-functional {m = (l , ul)} k,v∈m k,v'∈m = ListAB-functional ul k,v∈m k,v'∈m
data Provenance (k : A) (m₁ m₂ : Map) : Set (a b) where
both : (v₁ v₂ : B) (k , v₁) m₁ (k , v₂) m₂ Provenance k m₁ m₂
in₁ : (v₁ : B) (k , v₁) m₁ ¬ k ∈k m₂ Provenance k m₁ m₂
in₂ : (v₂ : B) ¬ k ∈k m₁ (k , v₂) m₂ Provenance k m₁ m₂
module _ (f : B B B) where
open ImplInsert f renaming
( insert to insert-impl
; merge to merge-impl
)
insert : A B Map Map
insert k v (kvs , uks) = (insert-impl k v kvs , insert-preserves-Unique uks)
merge : Map Map Map
merge (kvs₁ , _) (kvs₂ , uks₂) = (merge-impl kvs₁ kvs₂ , merge-preserves-Unique kvs₁ kvs₂ uks₂)
MergeResult : {k : A} {m₁ m₂ : Map} Provenance k m₁ m₂ Set (a b)
MergeResult {k} {m₁} {m₂} (both v₁ v₂ _ _) = (k , f v₁ v₂) merge m₁ m₂
MergeResult {k} {m₁} {m₂} (in v₁ _ _) = (k , v₁) merge m₁ m₂
MergeResult {k} {m₁} {m₂} (in v₂ _ _) = (k , v₂) merge m₁ m₂
merge-provenance : (m₁ m₂ : Map) (k : A) k ∈k merge m₁ m₂ Σ (Provenance k m₁ m₂) MergeResult
merge-provenance m₁@(l₁ , u₁) m₂@(l₂ , u₂) k k∈km₁m₂
with ∈k-dec k l₁ | ∈k-dec k l₂
... | yes k∈kl₁ | yes k∈kl₂ =
let
(v₁ , k,v₁∈l₁) = locate k∈kl₁
(v₂ , k,v₂∈l₂) = locate k∈kl₂
in
(both v₁ v₂ k,v₁∈l₁ k,v₂∈l₂ , merge-combines u₁ u₂ k,v₁∈l₁ k,v₂∈l₂)
... | yes k∈kl₁ | no k∉kl₂ =
let
(v₁ , k,v₁∈l₁) = locate k∈kl₁
in
(in v₁ k,v₁∈l₁ k∉kl₂ , merge-preserves-∈₂ u₁ k,v₁∈l₁ k∉kl₂)
... | no k∉kl₁ | yes k∈kl₂ =
let
(v₂ , k,v₂∈l₂) = locate k∈kl₂
in
(in v₂ k∉kl₁ k,v₂∈l₂ , merge-preserves-∈₁ k∉kl₁ k,v₂∈l₂)
... | no k∉kl₁ | no k∉kl₂ = absurd (merge-preserves-∉ k∉kl₁ k∉kl₂ k∈km₁m₂)
module _ (_≈_ : B B Set b) where
open ImplRelation _≈_ renaming (subset to subset-impl)
subset : Map Map Set (a b)
subset (kvs₁ , _) (kvs₂ , _) = subset-impl kvs₁ kvs₂
lift : Map Map Set (a b)
lift m₁ m₂ = subset m₁ m₂ × subset m₂ m₁
module _ (f : B B B) where
module _ (f-comm : (b₁ b₂ : B) f b₁ b₂ f b₂ b₁) where
merge-comm : (m₁ m₂ : Map) lift (_≡_) (merge f m₁ m₂) (merge f m₂ m₁)
merge-comm m₁ m₂ = (merge-comm-subset m₁ m₂ , merge-comm-subset m₂ m₁)
where
merge-comm-subset : (m₁ m₂ : Map) subset (_≡_) (merge f m₁ m₂) (merge f m₂ m₁)
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merge-comm-subset m₁@(l₁ , u₁) m₂@(l₂ , u₂) k v k,v∈m₁m₂
with merge-provenance f m₁ m₂ k (∈-cong proj₁ k,v∈m₁m₂)
... | (both v₁ v₂ v₁∈m₁ v₂∈m₂ , v₁v₂∈m₁m₂)
rewrite Map-functional {m = merge f m₁ m₂} k,v∈m₁m₂ v₁v₂∈m₁m₂ =
(f v₂ v₁ , (f-comm v₁ v₂ , ImplInsert.merge-combines f u₂ u₁ v₂∈m₂ v₁∈m₁))
... | (in v₁ v₁∈m₁ k∉km₂ , v₁∈m₁m₂)
rewrite Map-functional {m = merge f m₁ m₂} k,v∈m₁m₂ v₁∈m₁m₂ =
(v₁ , (refl , ImplInsert.merge-preserves-∈₁ f k∉km₂ v₁∈m₁))
... | (in v₂ k∉km₁ v₂∈m₂ , v₂∈m₁m₂)
rewrite Map-functional {m = merge f m₁ m₂} k,v∈m₁m₂ v₂∈m₁m₂ =
(v₂ , (refl , ImplInsert.merge-preserves-∈₂ f u₂ v₂∈m₂ k∉km₁))