{-# OPTIONS --without-K --safe #-}
module Data.These.Base where
open import Level
open import Data.Sum.Base using (_⊎_; [_,_]′)
open import Function.Base
private
variable
a b c d e f : Level
A : Set a
B : Set b
C : Set c
D : Set d
E : Set e
F : Set f
data These {a b} (A : Set a) (B : Set b) : Set (a ⊔ b) where
this : A → These A B
that : B → These A B
these : A → B → These A B
fromSum : A ⊎ B → These A B
fromSum = [ this , that ]′
map : (f : A → B) (g : C → D) → These A C → These B D
map f g (this a) = this (f a)
map f g (that b) = that (g b)
map f g (these a b) = these (f a) (g b)
map₁ : (f : A → B) → These A C → These B C
map₁ f = map f id
map₂ : (g : B → C) → These A B → These A C
map₂ = map id
fold : (A → C) → (B → C) → (A → B → C) → These A B → C
fold l r lr (this a) = l a
fold l r lr (that b) = r b
fold l r lr (these a b) = lr a b
foldWithDefaults : A → B → (A → B → C) → These A B → C
foldWithDefaults a b lr = fold (flip lr b) (lr a) lr
swap : These A B → These B A
swap = fold that this (flip these)
alignWith : (These A C → E) → (These B D → F) → These A B → These C D → These E F
alignWith f g (this a) (this c) = this (f (these a c))
alignWith f g (this a) (that d) = these (f (this a)) (g (that d))
alignWith f g (this a) (these c d) = these (f (these a c)) (g (that d))
alignWith f g (that b) (this c) = these (f (that c)) (g (this b))
alignWith f g (that b) (that d) = that (g (these b d))
alignWith f g (that b) (these c d) = these (f (that c)) (g (these b d))
alignWith f g (these a b) (this c) = these (f (these a c)) (g (this b))
alignWith f g (these a b) (that d) = these (f (this a)) (g (these b d))
alignWith f g (these a b) (these c d) = these (f (these a c)) (g (these b d))
align : These A B → These C D → These (These A C) (These B D)
align = alignWith id id