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1. maybeRead :: Read a => String -> Maybe a

   cabal-debian	Debian.Debianize.Prelude

   No documentation available.

2. maybeDecompress :: ByteString -> ByteString

   cabal-install	Distribution.Client.GZipUtils

   Attempts to decompress the bytes under the assumption that "data format" error at the very beginning of the stream means that it is already decompressed. Caller should make sanity checks to verify that it is not, in fact, garbage. This is to deal with http proxies that lie to us and transparently decompress without removing the content-encoding header. See: https://github.com/haskell/cabal/issues/678

3. maybeRepoRemote :: Repo -> Maybe RemoteRepo

   cabal-install	Distribution.Client.Types.Repo

   Extract RemoteRepo from Repo if remote.

4. maybeColor :: Handle -> [SGR] -> String -> IO String

   cabal2nix	Distribution.Nixpkgs.Color

   If the given Handle should be colored, wrap a String in SGR codes.

5. maybeBuildTopEntity :: Maybe String -> Name -> Q (TExp (Maybe TopEntity))

   clash-prelude	Clash.Annotations.TH

   Return a typed 'Maybe TopEntity' expression given a Name. This will return an TExp of Nothing if TopEntity generation failed.

6. maybeHasX :: (NFData a, NFDataX a) => a -> Maybe a

   clash-prelude	Clash.XException

   Fully evaluate a value, returning Nothing if it throws XException. Note that non-XException errors take precedence over XException ones.

   maybeHasX 42                    = Just 42
   maybeHasX (XException msg)      = Nothing
   maybeHasX (3, XException msg)   = Nothing
   maybeHasX (XException msg, _|_) = _|_
   maybeHasX (_|_, XException msg) = _|_
   maybeHasX (3, _|_)              = _|_
   maybeHasX _|_                   = _|_
   

7. maybeIsX :: a -> Maybe a

   clash-prelude	Clash.XException

   Evaluate a value to WHNF, returning Nothing if it throws XException.

   maybeIsX 42                  = Just 42
   maybeIsX (XException msg)    = Nothing
   maybeIsX (3, XException msg) = Just (3, XException msg)
   maybeIsX (3, _|_)            = Just (3, _|_)
   maybeIsX _|_                 = _|_
   

8. maybeX :: (String -> b) -> (a -> b) -> MaybeX a -> b

   clash-prelude	Clash.XException.MaybeX

   Map functions over both constructors.

9. maybeReader :: (String -> Maybe a) -> ReadM a

   configuration-tools	Configuration.Utils.CommandLine

   Convert a function producing a Maybe into a reader.

10. maybeOption :: a -> Bool -> (a -> a) -> Maybe a -> Maybe a

    configuration-tools	Configuration.Utils.Maybe

    Command line parser for record Maybe values

    Example:

    data Setting = Setting
    { _setA ∷ !Int
    , _setB ∷ !String
    }
    deriving (Show, Read, Eq, Ord, Typeable)
    
    $(makeLenses ''Setting)
    
    defaultSetting ∷ Setting
    defaultSetting = Setting
    { _setA = 0
    , _setB = 1
    }
    
    instance ToJSON Setting where
    toJSON setting = object
    [ "a" .= _setA setting
    , "b" .= _setB setting
    ]
    
    instance FromJSON (Setting → Setting) where
    parseJSON = withObject "Setting" $ \o → id
    <$< setA ..: "a" % o
    <*< setB ..: "b" % o
    
    instance FromJSON Setting where
    parseJSON v = parseJSON v <*> pure defaultSetting
    
    pSetting ∷ MParser Setting
    pSetting = id
    <$< setA .:: option auto
    % short 'a'
    <> metavar "INT"
    <> help "set a"
    <*< setB .:: option auto
    % short 'b'
    <> metavar "INT"
    <> help "set b"
    
    -- | Use 'Setting' as 'Maybe' in a configuration:
    --
    data Config = Config
    { _maybeSetting ∷ !(Maybe Setting)
    }
    deriving (Show, Read, Eq, Ord, Typeable)
    
    $(makeLenses ''Config)
    
    defaultConfig ∷ Config
    defaultConfig = Config
    { _maybeSetting = defaultSetting
    }
    
    instance ToJSON Config where
    toJSON config = object
    [ "setting" .= maybeSetting
    ]
    
    instance FromJSON (Config → Config) where
    parseJSON = withObject "Config" $ \o → id
    <$< maybeSetting %.: "setting" % o
    
    pConfig ∷ MParser Config
    pConfig = id
    <$< maybeSetting %:: (maybeOption defaultSetting
    <$> pEnableSetting
    <*> pSetting)
    where
    pEnableSetting = boolOption
    % long "setting-enable"
    <> value False
    <> help "Enable configuration flags for setting"
    

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