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See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + +Please see COPYING for the license. + diff --git a/Data/Convertible.hs b/Data/Convertible.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible.hs @@ -0,0 +1,40 @@ +{- +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +{- | + Module : Data.Convertible.Base + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +This is a library to provide a uniform interface for safe conversions between +different types of data. To get started reading about it, consult: + +"Data.Convertible.Base" for information about the conversions themselves + +"Data.Convertible.Utils" for helpful tools for people writing 'Convertible' instances + +"Data.Convertible.Instances" for a large collection of ready-built 'Convertible' instances + +You can import these modules individually, or this module will export the entire library +for you. +-} + +module Data.Convertible ( + module Data.Convertible.Base, + module Data.Convertible.Utils, + module Data.Convertible.Instances + ) +where +import Data.Convertible.Base +import Data.Convertible.Utils +import Data.Convertible.Instances diff --git a/Data/Convertible/Base.hs b/Data/Convertible/Base.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Base.hs @@ -0,0 +1,113 @@ +{- +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +{- | + Module : Data.Convertible.Base + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +-} + +module Data.Convertible.Base( -- * The conversion process + convert, + Convertible(..), + -- * Handling the results + ConvertResult, + ConvertError(..), + convError, + prettyConvertError + ) +where +import Control.Monad.Error +import Data.Typeable + +{- | The result of a safe conversion via 'safeConvert'. -} +type ConvertResult a = Either ConvertError a + +---------------------------------------------------------------------- +-- Conversions +---------------------------------------------------------------------- + +{- | A typeclass that represents something that can be converted. +A @Convertible a b@ instance represents an @a@ that can be converted to a @b@. -} +class Convertible a b where + {- | Convert @a@ to @b@, returning Right on success and Left on error. + For a simpler interface, see 'convert'. -} + safeConvert :: a -> ConvertResult b + +{- +{- | Any type can be converted to itself. -} +instance Convertible a a where + safeConvert x = return x +-} + +{- +{- | Lists of any convertible type can be converted. -} +instance Convertible a b => Convertible [a] [b] where + safeConvert = mapM safeConvert +-} + +{- | Convert from one type of data to another. Raises an exception if there is +an error with the conversion. For a function that does not raise an exception +in that case, see 'safeConvert'. -} +convert :: Convertible a b => a -> b +convert x = + case safeConvert x of + Left e -> error (prettyConvertError e) + Right r -> r + +{- +instance Convertible Int Double where + safeConvert = return . fromIntegral +instance Convertible Double Int where + safeConvert = return . truncate -- could do bounds checking here +instance Convertible Integer Double where + safeConvert = return . fromIntegral +instance Convertible Double Integer where + safeConvert = return . truncate +-} + +---------------------------------------------------------------------- +-- Error Handling +---------------------------------------------------------------------- + +{- | How we indicate that there was an error. -} +data ConvertError = ConvertError { + convSourceValue :: String, + convSourceType :: String, + convDestType :: String, + convErrorMessage :: String} + deriving (Eq, Read, Show) + +instance Error ConvertError where + strMsg x = ConvertError "(unknown)" "(unknown)" "(unknown)" x + +convError' :: (Show a, Typeable a, Typeable b) => + String -> a -> b -> ConvertResult b +convError' msg inpval retval = + Left $ ConvertError { + convSourceValue = show inpval, + convSourceType = show . typeOf $ inpval, + convDestType = show . typeOf $ retval, + convErrorMessage = msg} + +convError :: (Show a, Typeable a, Typeable b) => + String -> a -> ConvertResult b +convError msg inpval = + convError' msg inpval undefined + +prettyConvertError :: ConvertError -> String +prettyConvertError (ConvertError sv st dt em) = + "Convertible: error converting source data " ++ sv ++ " of type " ++ st + ++ " to type " ++ dt ++ ": " ++ em + diff --git a/Data/Convertible/Instances.hs b/Data/Convertible/Instances.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Instances.hs @@ -0,0 +1,36 @@ +{- +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +{- | + Module : Data.Convertible.Instances + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +Collection of ready-made 'Data.Convertible.Convertible' instances. See +each individual module for more docs: + +"Data.Convertible.Instances.Map" + +"Data.Convertible.Instances.Num" + +"Data.Convertible.Instances.Time" + +You can find a list of these instances at 'Data.Convertible.Base.Convertible'. +-} + +module Data.Convertible.Instances( + ) where + +import Data.Convertible.Instances.Map() +import Data.Convertible.Instances.Num() +import Data.Convertible.Instances.Time() diff --git a/Data/Convertible/Instances/Map.hs b/Data/Convertible/Instances/Map.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Instances/Map.hs @@ -0,0 +1,30 @@ +{- | + Module : Data.Convertible.Instances.Map + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +Instances to convert between Map and association list. + +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +module Data.Convertible.Instances.Map() +where + +import Data.Convertible.Base + +import qualified Data.Map as Map + +instance Ord k => Convertible [(k, a)] (Map.Map k a) where + safeConvert = return . Map.fromList +instance Convertible (Map.Map k a) [(k, a)] where + safeConvert = return . Map.toList diff --git a/Data/Convertible/Instances/Num.hs b/Data/Convertible/Instances/Num.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Instances/Num.hs @@ -0,0 +1,671 @@ +{- | + Module : Data.Convertible.Instances.Num + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +Numeric instances for Convertible. + +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +These instances perform conversion between numeric types such as Double, Int, Integer, +Rational, and the like. Here are some notes about the conversion process: + +Conversions from floating-point types such as Double to integral types are dune via the +'truncate' function. This is a somewhat arbitrary decision; if you need different +behavior, you will have to write your own instance or manually perform the conversion. + +All conversions perform bounds checking. If a value is too large for its destination +type, you will get a 'ConvertError' informing you of this. Note that this behavior +differs from functions in the Haskell standard libraries, which will perform the +conversion without error, but give you garbage in the end. + +Conversions do not perform precision checking; loss of precision is implied with certain +conversions (for instance, Double to Float) and this is not an error. +-} + +module Data.Convertible.Instances.Num() +where + +import Data.Convertible.Base +import Data.Convertible.Utils +import Data.Int +import Data.Word + +------------------------------------------------------------ + +{- The following instances generated by this code: + +fp = ["Double", "Float", "Rational"] +int = ["Int", "Int8", "Int16", "Int32", "Int64", "Word", "Word8", "Word16", "Word32", + "Word64"] +allItems l1 l2 = concatMap (\x -> map (\y -> (x, y)) int) fp +work = allItems fp int +printIt (f, i) = + "instance Convertible " ++ f ++ " " ++ i ++ " where \n\ + \ safeConvert = boundedConversion (return . truncate)\n\ + \instance Convertible " ++ i ++ " " ++ f ++ " where \n\ + \ safeConvert = return . fromIntegral\n" + +main = mapM_ (putStrLn . printIt) work +-} + +instance Convertible Double Int where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int Double where + safeConvert = return . fromIntegral + +instance Convertible Double Int8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int8 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Int16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int16 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Int32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int32 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Int64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int64 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Word where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word Double where + safeConvert = return . fromIntegral + +instance Convertible Double Word8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word8 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Word16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word16 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Word32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word32 Double where + safeConvert = return . fromIntegral + +instance Convertible Double Word64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word64 Double where + safeConvert = return . fromIntegral + +instance Convertible Float Int where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int Float where + safeConvert = return . fromIntegral + +instance Convertible Float Int8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int8 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Int16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int16 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Int32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int32 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Int64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int64 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Word where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word Float where + safeConvert = return . fromIntegral + +instance Convertible Float Word8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word8 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Word16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word16 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Word32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word32 Float where + safeConvert = return . fromIntegral + +instance Convertible Float Word64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word64 Float where + safeConvert = return . fromIntegral + +instance Convertible Rational Int where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Int8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int8 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Int16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int16 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Int32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int32 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Int64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Int64 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Word where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Word8 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word8 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Word16 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word16 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Word32 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word32 Rational where + safeConvert = return . fromIntegral + +instance Convertible Rational Word64 where + safeConvert = boundedConversion (return . truncate) +instance Convertible Word64 Rational where + safeConvert = return . fromIntegral + + +------------------------------------------------------------ +{- The following instances generated by this code: + +int = ["Int", "Int8", "Int16", "Int32", "Int64", "Word", "Word8", "Word16", "Word32", + "Word64"] +allItems l1 l2 = concatMap (\x -> map (\y -> (x, y)) l1) l2 +work = filter (\(a, b) -> a /= b) (allItems int int) +printIt (f, i) = + "instance Convertible " ++ f ++ " " ++ i ++ " where \n\ + \ safeConvert = boundedConversion (return . fromIntegral)\n" + +printInteger i = + "instance Convertible Integer " ++ i ++ " where \n\ + \ safeConvert = boundedConversion (return . fromIntegral)\n\ + \instance Convertible " ++ i ++ " Integer where \n\ + \ safeConvert = return . fromIntegral\n\n" + +main = do mapM_ (putStrLn . printIt) work + mapM_ (putStrLn . printInteger) int +-} + +instance Convertible Int Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int8 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int16 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int32 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Int64 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word8 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word16 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word32 Word64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Int where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Int8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Int16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Int32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Int64 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Word where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Word8 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Word16 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Word64 Word32 where + safeConvert = boundedConversion (return . fromIntegral) + +instance Convertible Integer Int where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Int Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Int8 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Int8 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Int16 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Int16 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Int32 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Int32 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Int64 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Int64 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Word where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Word Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Word8 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Word8 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Word16 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Word16 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Word32 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Word32 Integer where + safeConvert = return . fromIntegral + + +instance Convertible Integer Word64 where + safeConvert = boundedConversion (return . fromIntegral) +instance Convertible Word64 Integer where + safeConvert = return . fromIntegral + + +------------------------------------------------------------ + +instance Convertible Integer Double where + safeConvert = return . fromIntegral +instance Convertible Integer Float where + safeConvert = return . fromIntegral +instance Convertible Integer Rational where + safeConvert = return . fromIntegral +instance Convertible Double Integer where + safeConvert = return . truncate +instance Convertible Float Integer where + safeConvert = return . truncate +instance Convertible Rational Integer where + safeConvert = return . truncate + +instance Convertible Float Double where + safeConvert = return . fromRational . toRational +instance Convertible Double Float where + safeConvert = return . fromRational . toRational +instance Convertible Float Rational where + safeConvert = return . toRational +instance Convertible Rational Float where + safeConvert = return . fromRational +instance Convertible Double Rational where + safeConvert = return . toRational +instance Convertible Rational Double where + safeConvert = return . fromRational + +------------------------------------------------------------ +instance Convertible Char Integer where + safeConvert = return . fromIntegral . fromEnum +instance Convertible Integer Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + +------------------------------------------------------------ +{- These instances generated by: + +int = ["Int", "Int8", "Int16", "Int32", "Int64", "Word", "Word8", "Word16", "Word32", + "Word64"] +printIt i = + "instance Convertible Char " ++ i ++ " where \n\ + \ safeConvert = boundedConversion (return . fromIntegral . fromEnum)\n\ + \instance Convertible " ++ i ++ " Char where \n\ + \ safeConvert = boundedConversion (return . toEnum . fromIntegral)\n\n" + +main = do mapM_ (putStrLn . printIt) int +-} + +instance Convertible Char Int where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Int Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Int8 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Int8 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Int16 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Int16 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Int32 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Int32 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Int64 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Int64 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Word where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Word Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Word8 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Word8 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Word16 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Word16 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Word32 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Word32 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Char Word64 where + safeConvert = boundedConversion (return . fromIntegral . fromEnum) +instance Convertible Word64 Char where + safeConvert = boundedConversion (return . toEnum . fromIntegral) + + +instance Convertible Integer Integer where + safeConvert = return . id diff --git a/Data/Convertible/Instances/Time.hs b/Data/Convertible/Instances/Time.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Instances/Time.hs @@ -0,0 +1,212 @@ +{- | + Module : Data.Convertible.Instances.Time + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +Instances to convert between various time structures, both old- and new-style. + +At present, this module does not do full input validation. That is, it is possible +to get an exception rather than a Left result from these functions if your input is +invalid, particularly when converting from the old-style System.Time structures. + +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +module Data.Convertible.Instances.Time() +where + +import Data.Convertible.Base +import Data.Convertible.Utils +import Data.Convertible.Instances.Num() +import qualified System.Time as ST +import Data.Time +import Data.Time.Clock +import Data.Time.Clock.POSIX +import Data.Time.Calendar.OrdinalDate +import Data.Typeable +import Data.Ratio + +---------------------------------------------------------------------- +-- Intra-System.Time stuff +---------------------------------------------------------------------- + +instance Convertible ST.ClockTime ST.CalendarTime where + safeConvert = return . ST.toUTCTime + +instance Convertible ST.CalendarTime ST.ClockTime where + safeConvert = return . ST.toClockTime + +instance Convertible ST.ClockTime Integer where + safeConvert (ST.TOD x _) = return x + +instance Convertible Integer ST.ClockTime where + safeConvert x = return $ ST.TOD x 0 + +---------------------------------------------------------------------- +-- Intra-Data.Time stuff +---------------------------------------------------------------------- + +------------------------------ POSIX and UTC times + +instance Typeable NominalDiffTime where + typeOf _ = mkTypeName "NominalDiffTime" + +instance Typeable UTCTime where + typeOf _ = mkTypeName "UTCTime" + +{- Covered under Real a +instance Convertible Rational POSIXTime where + safeConvert = return . fromRational +-} + +instance Convertible Rational POSIXTime where + safeConvert = return . fromRational +instance Convertible Integer POSIXTime where + safeConvert = return . fromInteger +instance Convertible Int POSIXTime where + safeConvert = return . fromIntegral +instance Convertible Double POSIXTime where + safeConvert = return . fromRational . toRational + +instance Convertible POSIXTime Integer where + safeConvert = return . truncate +instance Convertible POSIXTime Rational where + safeConvert = return . toRational +instance Convertible POSIXTime Double where + safeConvert = return . fromRational . toRational +instance Convertible POSIXTime Int where + safeConvert = boundedConversion (return . truncate) + +instance Convertible POSIXTime UTCTime where + safeConvert = return . posixSecondsToUTCTime +instance Convertible UTCTime POSIXTime where + safeConvert = return . utcTimeToPOSIXSeconds + +instance Convertible Rational UTCTime where + safeConvert a = safeConvert a >>= return . posixSecondsToUTCTime +instance Convertible Integer UTCTime where + safeConvert a = safeConvert a >>= return . posixSecondsToUTCTime +instance Convertible Int UTCTime where + safeConvert a = safeConvert a >>= return . posixSecondsToUTCTime +instance Convertible Double UTCTime where + safeConvert a = safeConvert a >>= return . posixSecondsToUTCTime + +instance Convertible UTCTime Rational where + safeConvert = safeConvert . utcTimeToPOSIXSeconds +instance Convertible UTCTime Integer where + safeConvert = safeConvert . utcTimeToPOSIXSeconds +instance Convertible UTCTime Double where + safeConvert = safeConvert . utcTimeToPOSIXSeconds +instance Convertible UTCTime Int where + safeConvert = boundedConversion (safeConvert . utcTimeToPOSIXSeconds) + +------------------------------ LocalTime stuff + +instance Convertible UTCTime ZonedTime where + safeConvert = return . utcToZonedTime utc +instance Convertible POSIXTime ZonedTime where + safeConvert = return . utcToZonedTime utc . posixSecondsToUTCTime +instance Convertible ZonedTime UTCTime where + safeConvert = return . zonedTimeToUTC +instance Convertible ZonedTime POSIXTime where + safeConvert = return . utcTimeToPOSIXSeconds . zonedTimeToUTC + +{- Too obvious? +instance Convertible LocalTime Day where + safeConvert = return . localDay +instance Convertible LocalTime TimeOfDay where + safeConvert = return . localTimeOfDay +-} + +---------------------------------------------------------------------- +-- Conversions between old and new time +---------------------------------------------------------------------- +instance Convertible ST.CalendarTime ZonedTime where + safeConvert ct = return $ ZonedTime { + zonedTimeToLocalTime = LocalTime { + localDay = fromGregorian (fromIntegral $ ST.ctYear ct) + (1 + (fromEnum $ ST.ctMonth ct)) + (ST.ctDay ct), + localTimeOfDay = TimeOfDay { + todHour = ST.ctHour ct, + todMin = ST.ctMin ct, + todSec = (fromIntegral $ ST.ctSec ct) + + fromRational (ST.ctPicosec ct % 1000000000000) + } + }, + zonedTimeZone = TimeZone { + timeZoneMinutes = ST.ctTZ ct `div` 60, + timeZoneSummerOnly = ST.ctIsDST ct, + timeZoneName = ST.ctTZName ct} +} + +instance Convertible ST.CalendarTime POSIXTime where + safeConvert a = do r <- (safeConvert a)::ConvertResult ST.ClockTime + safeConvert r +instance Convertible ST.CalendarTime UTCTime where + safeConvert a = do r <- (safeConvert a)::ConvertResult POSIXTime + safeConvert r + +instance Convertible ST.ClockTime POSIXTime where + safeConvert (ST.TOD x y) = return $ fromRational $ + fromInteger x `plusorminus` fromRational (y % 1000000000000) + where plusorminus = if x < 0 then (-) else (+) +instance Convertible ST.ClockTime UTCTime where + safeConvert a = do r <- (safeConvert a)::ConvertResult POSIXTime + safeConvert r +instance Convertible ST.ClockTime ZonedTime where + safeConvert a = do r <- (safeConvert a)::ConvertResult UTCTime + safeConvert r + +instance Convertible POSIXTime ST.ClockTime where + safeConvert x = return $ ST.TOD rsecs rpico + where rsecs = (truncate x :: Integer) + rpico = truncate $ abs $ 1000000000000 * (x - (fromIntegral rsecs)) +instance Convertible UTCTime ST.ClockTime where + safeConvert = safeConvert . utcTimeToPOSIXSeconds + +instance Convertible ZonedTime ST.CalendarTime where + safeConvert zt = return $ ST.CalendarTime { + ST.ctYear = fromIntegral year, + ST.ctMonth = toEnum (month - 1), + ST.ctDay = day, + ST.ctHour = todHour ltod, + ST.ctMin = todMin ltod, + ST.ctSec = secs, + ST.ctPicosec = truncate $ (((toRational (todSec ltod) - (toRational secs)) * 1000000000000)::Rational), + ST.ctWDay = toEnum . snd . sundayStartWeek . localDay . zonedTimeToLocalTime $ zt, + ST.ctYDay = snd . toOrdinalDate . localDay . zonedTimeToLocalTime $ zt, + ST.ctTZName = timeZoneName . zonedTimeZone $ zt, + ST.ctTZ = (timeZoneMinutes . zonedTimeZone $ zt) * 60, + ST.ctIsDST = timeZoneSummerOnly . zonedTimeZone $ zt + } + where (year, month, day) = toGregorian . localDay . zonedTimeToLocalTime $ zt + ltod = localTimeOfDay . zonedTimeToLocalTime $ zt + secs = (truncate . todSec $ ltod)::Int +instance Convertible POSIXTime ST.CalendarTime where + safeConvert pt = do r <- (safeConvert pt)::ConvertResult ZonedTime + safeConvert r +instance Convertible UTCTime ST.CalendarTime where + safeConvert = safeConvert . utcTimeToPOSIXSeconds + +instance Convertible ST.TimeDiff NominalDiffTime where + {- This is a clever hack. We convert the TimeDiff to a ClockTime, applying + it as a diff vs. the epoch. Converting this ClockTime to a POSIXTime yiels + the NominalDiffTime we want, since a POSIXTime is a NominalDiffTime vs. the + epoch. -} + safeConvert td = safeConvert clockTime + where clockTime = ST.addToClockTime td (ST.TOD 0 0) +instance Convertible NominalDiffTime ST.TimeDiff where + {- Similar clever hack as above. -} + safeConvert ndt = + do clockt <- safeConvert ndt + return (ST.diffClockTimes clockt (ST.TOD 0 0)) diff --git a/Data/Convertible/Utils.hs b/Data/Convertible/Utils.hs new file mode 100644 --- /dev/null +++ b/Data/Convertible/Utils.hs @@ -0,0 +1,52 @@ +{- +Copyright (C) 2009 John Goerzen + +All rights reserved. + +For license and copyright information, see the file COPYRIGHT + +-} + +{- | + Module : Data.Convertible.Utils + Copyright : Copyright (C) 2009 John Goerzen + License : LGPL + + Maintainer : John Goerzen + Stability : provisional + Portability: portable + +-} + +module Data.Convertible.Utils(boundedConversion, + mkTypeName + ) +where +import Data.Convertible.Base +import Data.Typeable + +{- | Utility function to perform bounds checking as part of a conversion. + +Does this be examining the bounds of the destination type, converting to the type of +the source via 'safeConvert', comparing to the source value. Results in an error +if the conversion is out of bounds. -} +boundedConversion :: (Ord a, Bounded b, Show a, Show b, Convertible a Integer, + Convertible b Integer, + Typeable a, Typeable b) => + (a -> ConvertResult b) -- ^ Function to do the conversion + -> a -- ^ Input data + -> ConvertResult b -- ^ Result +boundedConversion func inp = + do result <- func inp + let smallest = asTypeOf minBound result + let biggest = asTypeOf maxBound result + let smallest' = (convert smallest)::Integer + let biggest' = (convert biggest)::Integer + let inp' = (convert inp)::Integer + if inp' < smallest' || inp' > biggest' + then convError ("Input value outside of bounds: " ++ show (smallest, biggest)) + inp + else return result + +mkTypeName :: String -> TypeRep +mkTypeName name = mkTyConApp (mkTyCon name) [] diff --git a/Setup.lhs b/Setup.lhs new file mode 100644 --- /dev/null +++ b/Setup.lhs @@ -0,0 +1,6 @@ +#!/usr/bin/env runhaskell + +> import Distribution.Simple + +> main = defaultMain + diff --git a/convertible.cabal b/convertible.cabal new file mode 100644 --- /dev/null +++ b/convertible.cabal @@ -0,0 +1,78 @@ +Name: convertible +Version: 1.0.0 +License: LGPL +Maintainer: John Goerzen +Author: John Goerzen +Copyright: Copyright (c) 2009-2009 John Goerzen +license-file: COPYRIGHT +extra-source-files: COPYING +homepage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/convertible +Category: Data +synopsis: Typeclasses and instances for converting between types +Description: convertible provides a typeclass with a single function + that is designed to help convert between different types: numeric + values, dates and times, and the like. The conversions perform bounds + checking and return a pure Either value. This means that you need + not remember which specific function performs the conversion you + desire. + . + Also included in the package are optional instances that provide + conversion for various numeric and time types, as well as utilities + for writing your own instances. + . + Finally, there is a function that will raise an exception on + bounds-checking violation, or return a bare value otherwise, + implemented in terms of the safer function described above. + . + Convertible is also used by HDBC 2.0 for handling marshalling of + data to/from databases. + . + Convertible is backed by an extensive test suite and passes tests + on GHC and Hugs. +Stability: Stable +Build-Type: Simple + +Cabal-Version: >=1.2 + +flag splitBase + description: Choose the new smaller, split-up base package. +flag buildtests + description: Build the executable to run unit tests + default: False + +library + if flag(splitBase) + Build-Depends: base>=3, old-time, time, bytestring, containers, old-locale + else + Build-Depends: base<3 + Build-Depends: mtl + + GHC-Options: -O2 -Wall -fno-warn-orphans + + Exposed-Modules: Data.Convertible, + Data.Convertible.Base, + Data.Convertible.Utils, + Data.Convertible.Instances, + Data.Convertible.Instances.Map, + Data.Convertible.Instances.Num, + Data.Convertible.Instances.Time + + --Other-Modules: Database.HDBC.Utils + --Extensions: ExistentialQuantification, AllowOverlappingInstances, + -- AllowUndecidableInstances + Extensions: ExistentialQuantification, MultiParamTypeClasses, + UndecidableInstances, FlexibleInstances, + FlexibleContexts, TypeSynonymInstances + +Executable runtests + if flag(buildtests) + Buildable: True + else + Buildable: False + Build-Depends: HUnit, QuickCheck, testpack + Main-Is: runtests.hs + Hs-Source-Dirs: ., testsrc + GHC-Options: -O2 + Extensions: ExistentialQuantification, MultiParamTypeClasses, + UndecidableInstances, FlexibleInstances, + FlexibleContexts, TypeSynonymInstances