agda-spa/Utils.agda
Danila Fedorin 6fe8dc2a02 Add an 'iterate' function to Utils
Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>
2024-02-11 14:19:41 -08:00

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module Utils where
open import Data.Nat using (; suc)
open import Data.List using (List; []; _∷_; _++_)
open import Data.List.Membership.Propositional using (_∈_)
open import Data.List.Relation.Unary.All using (All; []; _∷_; map)
open import Data.List.Relation.Unary.Any using (Any; here; there) -- TODO: re-export these with nicer names from map
open import Relation.Binary.PropositionalEquality using (_≡_; sym; refl)
open import Relation.Nullary using (¬_)
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}
¬ 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
All-x∈xs : {a} {A : Set a} (xs : List A) All (λ x x xs) xs
All-x∈xs [] = []
All-x∈xs (x xs') = here refl map there (All-x∈xs xs')
iterate : {a} {A : Set a} (n : ) (f : A A) A A
iterate 0 _ a = a
iterate (suc n) f a = f (iterate n f a)