------------------------------------------------------------------------
-- The Agda standard library
--
-- Pointwise equality over lists parameterised by a setoid
------------------------------------------------------------------------

{-# OPTIONS --without-K --safe #-}

open import Relation.Binary using (Setoid)

module Data.List.Relation.Binary.Equality.Setoid {a } (S : Setoid a ) where

open import Data.Fin
open import Data.List.Base
open import Data.List.Relation.Binary.Pointwise as PW using (Pointwise)
open import Function using (_∘_)
open import Level
open import Relation.Binary renaming (Rel to Rel₂)
open import Relation.Binary.PropositionalEquality as P using (_≡_)
open import Relation.Unary as U using (Pred)

open Setoid S renaming (Carrier to A)

private
  variable
    p q : Level

------------------------------------------------------------------------
-- Definition of equality
------------------------------------------------------------------------

infix 4 _≋_

_≋_ : Rel₂ (List A) (a  )
_≋_ = Pointwise _≈_

open Pointwise public
  using ([]; _∷_)

------------------------------------------------------------------------
-- Relational properties
------------------------------------------------------------------------

≋-refl : Reflexive _≋_
≋-refl = PW.refl refl

≋-reflexive : _≡_  _≋_
≋-reflexive P.refl = ≋-refl

≋-sym : Symmetric _≋_
≋-sym = PW.symmetric sym

≋-trans : Transitive _≋_
≋-trans = PW.transitive trans

≋-isEquivalence : IsEquivalence _≋_
≋-isEquivalence = PW.isEquivalence isEquivalence

≋-setoid : Setoid _ _
≋-setoid = PW.setoid S

------------------------------------------------------------------------
-- List Operations
------------------------------------------------------------------------

------------------------------------------------------------------------
-- length

≋-length :  {xs ys}  xs  ys  length xs  length ys
≋-length = PW.Pointwise-length

------------------------------------------------------------------------
-- map

module _ {b ℓ₂} (T : Setoid b ℓ₂) where

  open Setoid T using () renaming (_≈_ to _≈′_)
  private
    _≋′_ = Pointwise _≈′_

  map⁺ :  {f}  f Preserves _≈_  _≈′_ 
          {xs ys}  xs  ys  map f xs ≋′ map f ys
  map⁺ {f} pres xs≋ys = PW.map⁺ f f (PW.map pres xs≋ys)

------------------------------------------------------------------------
-- _++_

++⁺ :  {ws xs ys zs}  ws  xs  ys  zs  ws ++ ys  xs ++ zs
++⁺ = PW.++⁺

++-cancelˡ :  xs {ys zs}  xs ++ ys  xs ++ zs  ys  zs
++-cancelˡ = PW.++-cancelˡ

++-cancelʳ :  {xs} ys zs  ys ++ xs  zs ++ xs  ys  zs
++-cancelʳ = PW.++-cancelʳ

------------------------------------------------------------------------
-- concat

concat⁺ :  {xss yss}  Pointwise _≋_ xss yss  concat xss  concat yss
concat⁺ = PW.concat⁺

------------------------------------------------------------------------
-- tabulate

tabulate⁺ :  {n} {f : Fin n  A} {g : Fin n  A} 
            (∀ i  f i  g i)  tabulate f  tabulate g
tabulate⁺ = PW.tabulate⁺

tabulate⁻ :  {n} {f : Fin n  A} {g : Fin n  A} 
            tabulate f  tabulate g  (∀ i  f i  g i)
tabulate⁻ = PW.tabulate⁻

------------------------------------------------------------------------
-- filter

module _ {P : Pred A p} (P? : U.Decidable P) (resp : P Respects _≈_)
  where

  filter⁺ :  {xs ys}  xs  ys  filter P? xs  filter P? ys
  filter⁺ xs≋ys = PW.filter⁺ P? P? resp (resp  sym) xs≋ys

------------------------------------------------------------------------
-- reverse

ʳ++⁺ : ∀{xs xs′ ys ys′}  xs  xs′  ys  ys′  xs ʳ++ ys  xs′ ʳ++ ys′
ʳ++⁺ = PW.ʳ++⁺

reverse⁺ :  {xs ys}  xs  ys  reverse xs  reverse ys
reverse⁺ = PW.reverse⁺