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diff --git a/Utility/DottedVersion.hs b/Utility/DottedVersion.hs
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+{- dotted versions, such as 1.0.1
+ -
+ - Copyright 2011-2014 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# OPTIONS_GHC -fno-warn-tabs #-}
+
+module Utility.DottedVersion where
+
+import Common
+
+data DottedVersion = DottedVersion String Integer
+	deriving (Eq)
+
+instance Ord DottedVersion where
+	compare (DottedVersion _ x) (DottedVersion _ y) = compare x y
+
+instance Show DottedVersion where
+	show (DottedVersion s _) = s
+
+{- To compare dotted versions like 1.7.7 and 1.8, they are normalized to
+ - a somewhat arbitrary integer representation. -}
+normalize :: String -> DottedVersion
+normalize v = DottedVersion v $ 
+	sum $ mult 1 $ reverse $ extend precision $ take precision $
+		map readi $ split "." v
+  where
+	extend n l = l ++ replicate (n - length l) 0
+	mult _ [] = []
+	mult n (x:xs) = (n*x) : mult (n*10^width) xs
+	readi :: String -> Integer
+	readi s = case reads s of
+		((x,_):_) -> x
+		_ -> 0
+	precision = 10 -- number of segments of the version to compare
+	width = length "yyyymmddhhmmss" -- maximum width of a segment