1 {-| Utility functions -}
3 module Ganeti.HTools.Utils
22 import qualified Text.JSON as J
23 import Text.Printf (printf)
25 import Ganeti.HTools.Types
29 -- | To be used only for debugging, breaks referential integrity.
30 debug :: Show a => a -> a
31 debug x = trace (show x) x
34 fromJResult :: Monad m => J.Result a -> m a
35 fromJResult (J.Error x) = fail x
36 fromJResult (J.Ok x) = return x
38 -- | Comma-join a string list.
39 commaJoin :: [String] -> String
40 commaJoin = intercalate ","
42 -- | Split a string on a separator and return an array.
43 sepSplit :: Char -> String -> [String]
45 | x == "" && xs == [] = []
48 | otherwise = x:(sepSplit sep ys)
49 where (x, xs) = break (== sep) s
52 -- | Partial application of sepSplit to @'.'@
53 commaSplit :: String -> [String]
54 commaSplit = sepSplit ','
56 -- Simple and slow statistical functions, please replace with better versions
58 -- | Mean value of a list.
59 meanValue :: Floating a => [a] -> a
60 meanValue lst = (sum lst) / (fromIntegral $ length lst)
62 -- | Standard deviation.
63 stdDev :: Floating a => [a] -> a
65 let mv = meanValue lst
66 square = (^ (2::Int)) -- silences "defaulting the constraint..."
67 av = sum $ map square $ map (\e -> e - mv) lst
68 bv = sqrt (av / (fromIntegral $ length lst))
71 -- | Coefficient of variation.
72 varianceCoeff :: Floating a => [a] -> a
73 varianceCoeff lst = (stdDev lst) / (fromIntegral $ length lst)
75 -- | Get an Ok result or print the error and exit
76 readData :: Result a -> IO a
81 exitWith $ ExitFailure 1
84 readEitherString :: (Monad m) => J.JSValue -> m String
87 J.JSString s -> return $ J.fromJSString s
88 _ -> fail "Wrong JSON type"
90 loadJSArray :: (Monad m) => String -> m [J.JSObject J.JSValue]
91 loadJSArray s = fromJResult $ J.decodeStrict s
93 fromObj :: (J.JSON a, Monad m) => String -> J.JSObject J.JSValue -> m a
95 case lookup k (J.fromJSObject o) of
96 Nothing -> fail $ printf "key '%s' not found in %s" k (show o)
97 Just val -> fromJResult $ J.readJSON val
99 asJSObject :: (Monad m) => J.JSValue -> m (J.JSObject J.JSValue)
100 asJSObject (J.JSObject a) = return a
101 asJSObject _ = fail "not an object"
103 asObjectList :: (Monad m) => [J.JSValue] -> m [J.JSObject J.JSValue]
104 asObjectList = sequence . map asJSObject