module Data.List.NonEmpty.Properties where
open import Category.Monad
open import Data.List as List using (List; []; _∷_; _++_)
open import Data.List.NonEmpty as List⁺
open import Data.List.Properties
open import Function
open import Relation.Binary.PropositionalEquality
open ≡-Reasoning
private
open module LMo {a} =
RawMonad {f = a} List.monad
using () renaming (_>>=_ to _⋆>>=_)
open module L⁺Mo {a} =
RawMonad {f = a} List⁺.monad
η : ∀ {a} {A : Set a}
(xs : List⁺ A) → head xs ∷ tail xs ≡ List⁺.toList xs
η _ = refl
toList-fromList : ∀ {a} {A : Set a} x (xs : List A) →
x ∷ xs ≡ List⁺.toList (x ∷ xs)
toList-fromList _ _ = refl
toList-⁺++ : ∀ {a} {A : Set a} (xs : List⁺ A) ys →
List⁺.toList xs ++ ys ≡
List⁺.toList (xs ⁺++ ys)
toList-⁺++ _ _ = refl
toList-⁺++⁺ : ∀ {a} {A : Set a} (xs ys : List⁺ A) →
List⁺.toList xs ++ List⁺.toList ys ≡
List⁺.toList (xs ⁺++⁺ ys)
toList-⁺++⁺ _ _ = refl
toList->>= : ∀ {ℓ} {A B : Set ℓ}
(f : A → List⁺ B) (xs : List⁺ A) →
(List⁺.toList xs ⋆>>= List⁺.toList ∘ f) ≡
(List⁺.toList (xs >>= f))
toList->>= f (x ∷ xs) = begin
List.concat (List.map (List⁺.toList ∘ f) (x ∷ xs)) ≡⟨ cong List.concat $ map-compose {g = List⁺.toList} {f = f} (x ∷ xs) ⟩
List.concat (List.map List⁺.toList (List.map f (x ∷ xs))) ∎