module Utils where

import Prelude (($), (+), (<>), (==))
import Data.Array as A
import Data.Maybe (Maybe(..), fromMaybe)
import Data.Tuple (Tuple(..))

attach_id :: forall a. Int -> Array a -> Array (Tuple Int a)
attach_id _ []  = []
attach_id i arr = case A.head arr of
  Just x -> [Tuple i x] <> attach_id (i + 1) (fromMaybe [] $ A.tail arr)
  Nothing -> []

remove_id :: forall a. Int -> Array (Tuple Int a) -> Array a
remove_id _ []  = []
remove_id i arr = case A.head arr of
  Just (Tuple n x) -> if i == n
                      then remove_id i (fromMaybe [] $ A.tail arr)
                      else [x] <> remove_id i (fromMaybe [] $ A.tail arr)
  Nothing -> []

id :: forall a. a -> a
id x = x