Revision 9188aeef Ganeti/HTools/Utils.hs

b/Ganeti/HTools/Utils.hs
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import Debug.Trace


  		





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-- * Debug functions


  		





  
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-- | To be used only for debugging, breaks referential integrity.


  		





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debug :: Show a => a -> a


  		





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debug x = trace (show x) x


  		





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fromJResult :: Monad m => J.Result a -> m a


  		





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fromJResult (J.Error x) = fail x


  		





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fromJResult (J.Ok x) = return x


  		





  
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-- * Miscelaneous


  		





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-- | Comma-join a string list.


  		





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commaJoin :: [String] -> String


  		





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commaSplit :: String -> [String]


  		





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commaSplit = sepSplit ','


  		





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-- * Mathematical functions


  		





  
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-- Simple and slow statistical functions, please replace with better versions


  		





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-- | Mean value of a list.


  		





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varianceCoeff :: Floating a => [a] -> a


  		





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varianceCoeff lst = (stdDev lst) / (fromIntegral $ length lst)


  		





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-- | Get an Ok result or print the error and exit


  		





  
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-- | Get an Ok result or print the error and exit.


  		





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readData :: Result a -> IO a


  		





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readData nd =


  		





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    (case nd of


  		





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         exitWith $ ExitFailure 1


  		





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       Ok x -> return x)


  		





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-- * JSON-related functions


  		





  
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-- | Converts a JSON Result into a monadic value.


  		





  
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fromJResult :: Monad m => J.Result a -> m a


  		





  
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fromJResult (J.Error x) = fail x


  		





  
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fromJResult (J.Ok x) = return x


  		





  
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-- | Tries to read a string from a JSON value.


  		





  
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--


  		





  
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-- In case the value was not a string, we fail the read (in the


  		





  
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-- context of the current monad.


  		





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readEitherString :: (Monad m) => J.JSValue -> m String


  		





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readEitherString v =


  		





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    case v of


  		





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      J.JSString s -> return $ J.fromJSString s


  		





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      _ -> fail "Wrong JSON type"


  		





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-- | Converts a JSON message into an array of JSON objects.


  		





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loadJSArray :: (Monad m) => String -> m [J.JSObject J.JSValue]


  		





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loadJSArray s = fromJResult $ J.decodeStrict s


  		





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-- | Reads a the value of a key in a JSON object.


  		





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fromObj :: (J.JSON a, Monad m) => String -> J.JSObject J.JSValue -> m a


  		





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fromObj k o =


  		





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    case lookup k (J.fromJSObject o) of


  		





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      Nothing -> fail $ printf "key '%s' not found in %s" k (show o)


  		





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      Just val -> fromJResult $ J.readJSON val


  		





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-- | Converts a JSON value into a JSON object.


  		





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asJSObject :: (Monad m) => J.JSValue -> m (J.JSObject J.JSValue)


  		





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asJSObject (J.JSObject a) = return a


  		





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asJSObject _ = fail "not an object"


  		





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-- | Coneverts a list of JSON values into a list of JSON objects.


  		





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asObjectList :: (Monad m) => [J.JSValue] -> m [J.JSObject J.JSValue]


  		





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asObjectList = sequence . map asJSObject


  		












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