module Hubris.Collections.LRUCache
  ( empty
  , insert
  ) where

import qualified Data.Map as M
import Data.Monoid (Sum (..))

type LRUCache a = M.Map a (Sum Int)

empty :: LRUCache a
empty = M.empty

insert :: a -> LRUCache a -> LRUCache a
insert = M.alter (fmap $ const 0)
  where