module Aoc

import Prelude

nums : String → List Int
nums s = map stringToInt $ filter (_/=_ "") $ split (trim s) " "

isDigit : Char -> Bool
isDigit '0' = True
isDigit '1' = True
isDigit '2' = True
isDigit '3' = True
isDigit '4' = True
isDigit '5' = True
isDigit '6' = True
isDigit '7' = True
isDigit '8' = True
isDigit '9' = True
isDigit _ = False

indexOf? : ∀ a. {{Eq a}} → a → List a → Maybe Nat
indexOf? {a} z xs = go Z z xs
  where
    go : Nat → a → List a → Maybe Nat
    go ix z Nil = Nothing
    go ix z (x :: xs) =
      if z == x then Just ix else go (S ix) z xs

-- if_then_else shorthand
-- Lean version uses a decidable instead of Bool
ite : ∀ a. Bool → a → a → a
ite c t e = if c then t else e

-- probably not super efficient, but it works
qsort : ∀ a. (a → a → Bool) → List a → List a
qsort lt Nil = Nil
qsort lt (x :: xs) = qsort lt (filter (λ y => not $ lt x y) xs) ++ x :: qsort lt (filter (lt x) xs)