, readEitherString
, loadJSArray
, fromObj
+ , tryFromObj
+ , fromJVal
, asJSObject
, asObjectList
, fromJResult
, tryRead
, formatTable
+ , annotateResult
) where
import Data.List
-import Control.Monad
import qualified Text.JSON as J
import Text.Printf (printf)
import Debug.Trace
+import Ganeti.HTools.Types
+
-- * Debug functions
-- | To be used only for debugging, breaks referential integrity.
-- * Mathematical functions
--- Simple and slow statistical functions, please replace with better versions
-
--- | Mean value of a list.
-meanValue :: Floating a => [a] -> a
-meanValue lst = sum lst / fromIntegral (length lst)
+-- Simple and slow statistical functions, please replace with better
+-- versions
--- | Standard deviation.
-stdDev :: Floating a => [a] -> a
-stdDev lst =
- let mv = meanValue lst
+-- | The covariance of the list
+varianceCoeff :: [Double] -> Double
+varianceCoeff lst =
+ let ll = fromIntegral (length lst)::Double -- length of list
+ mv = sum lst / ll -- mean value
av = foldl' (\accu em -> let d = em - mv in accu + d * d) 0.0 lst
- bv = sqrt (av / fromIntegral (length lst))
- in bv
-
--- | Coefficient of variation.
-varianceCoeff :: Floating a => [a] -> a
-varianceCoeff lst = stdDev lst / fromIntegral (length lst)
+ bv = sqrt (av / ll) -- stddev
+ cv = bv / ll -- covariance
+ in cv
-- * JSON-related functions
loadJSArray = fromJResult . J.decodeStrict
-- | Reads a the value of a key in a JSON object.
-fromObj :: (J.JSON a, Monad m) => String -> J.JSObject J.JSValue -> m a
+fromObj :: (J.JSON a, Monad m) => String -> [(String, J.JSValue)] -> m a
fromObj k o =
- case lookup k (J.fromJSObject o) of
+ case lookup k o of
Nothing -> fail $ printf "key '%s' not found in %s" k (show o)
Just val -> fromJResult $ J.readJSON val
+-- | Annotate a Result with an ownership information
+annotateResult :: String -> Result a -> Result a
+annotateResult owner (Bad s) = Bad $ owner ++ ": " ++ s
+annotateResult _ v = v
+
+-- | Try to extract a key from a object with better error reporting
+-- than fromObj
+tryFromObj :: (J.JSON a) =>
+ String -> [(String, J.JSValue)] -> String -> Result a
+tryFromObj t o k = annotateResult (t ++ " key '" ++ k ++ "'") (fromObj k o)
+
+-- | Small wrapper over readJSON.
+fromJVal :: (Monad m, J.JSON a) => J.JSValue -> m a
+fromJVal v =
+ case J.readJSON v of
+ J.Error s -> fail ("Cannot convert value " ++ show v ++ ", error: " ++ s)
+ J.Ok x -> return x
+
-- | Converts a JSON value into a JSON object.
asJSObject :: (Monad m) => J.JSValue -> m (J.JSObject J.JSValue)
asJSObject (J.JSObject a) = return a