clean up some ugly code

This commit is contained in:
Joey Hess 2013-09-27 19:52:36 -04:00
parent d6883dcd7f
commit c6032b0dab
5 changed files with 40 additions and 24 deletions

17
Utility/Data.hs Normal file
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@ -0,0 +1,17 @@
{- utilities for simple data types
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
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