pubsub-0.10: Utils/Data/List.hs

--------------------------------------------------------------------
-- |
-- Module    : Utils.Data.List
-- Copyright : (c) Sigbjorn Finne, 2009
-- License   : BSD3
--
-- Maintainer: Sigbjorn Finne <sof@forkIO.com>
-- Stability : provisional
-- Portability:
--
--------------------------------------------------------------------
module Utils.Data.List
       ( matchPrefix -- :: Eq a => [a] -> [a] -> Maybe [a]
       , transElem   -- :: Eq a => a -> a -> a -> a

       ) where


matchPrefix :: Eq a => [a] -> [a] -> Maybe [a]
matchPrefix [] xs = Just xs
matchPrefix (x:xs) (y:ys)
 | x == y = matchPrefix xs ys
 | otherwise = Nothing

transElem :: Eq a => a -> a -> a -> a
transElem t f x
 | t == x    = f
 | otherwise = x