{-# LANGUAGE OverloadedStrings #-} -- | Demo custom comparator module Main where import Control.Monad.IO.Class (liftIO) import Data.Default import Database.LevelDB customComparator :: Comparator customComparator = Comparator compare main :: IO () main = runResourceT $ do db <- open "/tmp/lvlcmptest" defaultOptions{ createIfMissing = True , comparator = Just customComparator } put db def "zzz" "" put db def "yyy" "" put db def "xxx" "" withIterator db def $ \iter -> do iterFirst iter iterItems iter >>= liftIO . print return ()