propellor/Utility/Data.hs

18 lines
399 B
Haskell

{- utilities for simple data types
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- License: BSD-2-clause
-}
module Utility.Data where
{- First item in the list that is not Nothing. -}
firstJust :: Eq a => [Maybe a] -> Maybe a
firstJust ms = case dropWhile (== Nothing) ms of
[] -> Nothing
(md:_) -> md
eitherToMaybe :: Either a b -> Maybe b
eitherToMaybe = either (const Nothing) Just