module Taskell.Data.Seq where

import ClassyPrelude

import Data.Sequence (deleteAt, insertAt, mapWithIndex, (!?))

(<#>) :: (Int -> a -> b) -> Seq a -> Seq b
(<#>) = mapWithIndex

extract :: Int -> Seq a -> Maybe (Seq a, a)
extract idx xs = (,) (deleteAt idx xs) <$> xs !? idx

shiftBy :: Int -> Int -> Seq a -> Maybe (Seq a)
shiftBy idx dir xs = do
    (a, current) <- extract idx xs
    pure $ insertAt (idx + dir) current a

bound :: Seq a -> Int -> Int
bound s i
    | i < 0 = 0
    | i >= length s = pred (length s)
    | otherwise = i