37 lines
751 B
Haskell
37 lines
751 B
Haskell
{- git-annex UUID type
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-
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- Copyright 2011 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
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module Types.UUID where
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import qualified Data.Map as M
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import qualified Data.UUID as U
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import Data.Maybe
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-- A UUID is either an arbitrary opaque string, or UUID info may be missing.
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data UUID = NoUUID | UUID String
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deriving (Eq, Ord, Show, Read)
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fromUUID :: UUID -> String
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fromUUID (UUID u) = u
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fromUUID NoUUID = ""
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class ToUUID a where
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toUUID :: a -> UUID
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instance ToUUID UUID where
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toUUID = id
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instance ToUUID String where
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toUUID [] = NoUUID
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toUUID s = UUID s
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isUUID :: String -> Bool
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isUUID = isJust . U.fromString
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type UUIDMap = M.Map UUID String
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