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-rw-r--r--Data/Opaque/Multiset.agda74
1 files changed, 69 insertions, 5 deletions
diff --git a/Data/Opaque/Multiset.agda b/Data/Opaque/Multiset.agda
index 2ba0a0e..99501d6 100644
--- a/Data/Opaque/Multiset.agda
+++ b/Data/Opaque/Multiset.agda
@@ -4,14 +4,20 @@
module Data.Opaque.Multiset where
import Data.List as L
+import Relation.Binary.Reasoning.Setoid as ≈-Reasoning
+import Data.Opaque.List as List
-open import Data.List.Relation.Binary.Permutation.Setoid as ↭ using (↭-setoid; prep)
+open import Algebra.Bundles using (CommutativeMonoid)
+open import Data.List.Effectful.Foldable using (foldable; ++-homo)
+open import Data.List.Relation.Binary.Permutation.Setoid as ↭ using (↭-setoid; ↭-refl)
open import Data.List.Relation.Binary.Permutation.Setoid.Properties using (map⁺; ++⁺; ++-comm)
-open import Data.Product using (_,_)
-open import Data.Product using (uncurry′)
+open import Algebra.Morphism using (IsMonoidHomomorphism)
+open import Data.Product using (_,_; uncurry′)
open import Data.Product.Relation.Binary.Pointwise.NonDependent using (_×ₛ_)
+open import Data.Setoid using (∣_∣)
open import Data.Setoid.Unit using (⊤ₛ)
-open import Function using (_⟶ₛ_; Func; _⟨$⟩_)
+open import Effect.Foldable using (RawFoldable)
+open import Function using (_⟶ₛ_; Func; _⟨$⟩_; id)
open import Function.Construct.Constant using () renaming (function to Const)
open import Level using (Level; _⊔_)
open import Relation.Binary using (Setoid)
@@ -50,7 +56,11 @@ opaque
∷ₛ : Aₛ ×ₛ Multisetₛ Aₛ ⟶ₛ Multisetₛ Aₛ
∷ₛ .to = uncurry′ _∷_
- ∷ₛ .cong = uncurry′ prep
+ ∷ₛ .cong = uncurry′ ↭.prep
+
+ [-]ₛ : Aₛ ⟶ₛ Multisetₛ Aₛ
+ [-]ₛ .to = L.[_]
+ [-]ₛ {Aₛ} .cong y = ↭.prep y (↭-refl Aₛ)
mapₛ : (Aₛ ⟶ₛ Bₛ) → Multisetₛ Aₛ ⟶ₛ Multisetₛ Bₛ
mapₛ f .to = map (to f)
@@ -65,3 +75,57 @@ opaque
→ (xs ys : Carrier)
→ ++ₛ ⟨$⟩ (xs , ys) ≈ ++ₛ ⟨$⟩ (ys , xs)
++ₛ-comm {Aₛ} xs ys = ++-comm Aₛ xs ys
+
+module _ (M : CommutativeMonoid c ℓ) where
+
+ open CommutativeMonoid M renaming (setoid to Mₛ)
+
+ opaque
+ unfolding Multiset List.fold-cong
+ fold : ∣ Multisetₛ Mₛ ∣ → ∣ Mₛ ∣
+ fold = List.fold monoid -- RawFoldable.fold foldable rawMonoid
+
+ fold-cong
+ : {xs ys : ∣ Multisetₛ Mₛ ∣}
+ → (let module [M]ₛ = Setoid (Multisetₛ Mₛ))
+ → (xs [M]ₛ.≈ ys)
+ → fold xs ≈ fold ys
+ fold-cong (↭.refl x) = cong (List.foldₛ monoid) x
+ fold-cong (↭.prep x≈y xs↭ys) = ∙-cong x≈y (fold-cong xs↭ys)
+ fold-cong
+ {x₀ L.∷ x₁ L.∷ xs}
+ {y₀ L.∷ y₁ L.∷ ys}
+ (↭.swap x₀≈y₁ x₁≈y₀ xs↭ys) = trans
+ (sym (assoc x₀ x₁ (fold xs))) (trans 
+ (∙-cong (trans (∙-cong x₀≈y₁ x₁≈y₀) (comm y₁ y₀)) (fold-cong xs↭ys))
+ (assoc y₀ y₁ (fold ys)))
+ fold-cong {xs} {ys} (↭.trans xs↭zs zs↭ys) = trans (fold-cong xs↭zs) (fold-cong zs↭ys)
+
+ foldₛ : Multisetₛ Mₛ ⟶ₛ Mₛ
+ foldₛ .to = fold
+ foldₛ .cong = fold-cong
+
+ opaque
+ unfolding fold
+ ++ₛ-homo
+ : (xs ys : ∣ Multisetₛ Mₛ ∣)
+ → foldₛ ⟨$⟩ (++ₛ ⟨$⟩ (xs , ys)) ≈ (foldₛ ⟨$⟩ xs) ∙ (foldₛ ⟨$⟩ ys)
+ ++ₛ-homo xs ys = ++-homo monoid id xs
+
+ []ₛ-homo : foldₛ ⟨$⟩ ([]ₛ ⟨$⟩ _) ≈ ε
+ []ₛ-homo = refl
+
+module _ (M N : CommutativeMonoid c ℓ) where
+
+ module M = CommutativeMonoid M
+ module N = CommutativeMonoid N
+
+ opaque
+ unfolding fold
+
+ fold-mapₛ
+ : (f : M.setoid ⟶ₛ N.setoid)
+ → IsMonoidHomomorphism M.rawMonoid N.rawMonoid (to f)
+ → {xs : ∣ Multisetₛ M.setoid ∣}
+ → foldₛ N ⟨$⟩ (mapₛ f ⟨$⟩ xs) N.≈ f ⟨$⟩ (foldₛ M ⟨$⟩ xs)
+ fold-mapₛ = List.fold-mapₛ M.monoid N.monoid