[Haskell-cafe] Data Type Inheritance ala OO - Inheritence -- howto best in Haskell ?

[David Barbour]

Look into Oleg's HList (heterogeneous list) and OOHaskell

http://homepages.cwi.nl/~ralf/HList/
http://homepages.cwi.nl/~ralf/OOHaskell/


On Thu, Jun 16, 2011 at 5:08 AM, kaffeepause73 <kaffeepause73 at yahoo.de>wrote:

> Dear all,
>
> I'm created a timeSignal datatype as container around a "Vector Double"
> data
> type (see simple code below) and subsequently started to instanciate Num &
> Eq to be able to perform operations on it. Additionally I want store ifno
> like an index, time information and eventually an inheritence log (the log
> is not yet in there).
>
> As I will in the end need up to 10 different datatypes, however using
> slightly different content (time signal, single value, distribution, ...) I
> ask myself, how I could define a super data-type with sub-data-types to
> inherit, but then also overload certain functions (like u would do in OO).
>
> What is best way in haskell to achieve this ? (I'm unsure wether haskell
> classes are what I'm looking for)
>
> Cheers Phil
>
> ########## Code below
>
> import qualified Data.Vector.Unboxed as V
>
> data TimeSig = TimeSig Int Double (V.Vector Double) -- signal Index
> timeStep
> data
>
> getVect :: TimeSig -> (V.Vector Double)
> getVect (TimeSig idx dt vect)= vect
>
> getIdx :: TimeSig -> Int
> getIdx (TimeSig idx dt vect) = idx
>
> getdt :: TimeSig -> Double
> getdt (TimeSig idx dt vect) = dt
>
> pzipWith :: (Double -> Double -> Double) -> TimeSig -> TimeSig -> TimeSig
> pzipWith f p1 p2 =  TimeSig idx dt vect
>              where
>                vect = V.zipWith f (getVect p1)  (getVect p2)
>                idx = getIdx p1
>                dt = getdt p1
>
> pmap :: (Double -> Double) -> TimeSig -> TimeSig
> pmap f p = TimeSig (getIdx p) (getdt p) (V.map f (getVect p))
>
> instance Num TimeSig
>      where
>      (+) p1 p2 = pzipWith (+) p1 p2
>      (-) p1 p2 = pzipWith (-) p1 p2
>      negate p1 = pmap negate p1
>      abs p1 = pmap abs p1
>      (*) p1 p2 = pzipWith (*) p1 p2
>
> instance Eq TimeSig where
>            (==) p1 p2 = (==) (getVect p1) (getVect p2)
>
>
> instance Show TimeSig where
>  show (TimeSig idx dt vect) = "TimeSignal Nr: " ++ show idx ++ "  dt: " ++
> show dt ++ " val:" ++ show vect
>
>
>
> main = do
>
>        let p = TimeSig 5 0.1 (V.fromList [0..10::Double])
>        putStrLn (show p)
>        putStrLn (show (p+p))
>
> --
> View this message in context:
> http://haskell.1045720.n5.nabble.com/Data-Type-Inheritance-ala-OO-Inheritence-howto-best-in-Haskell-tp4494800p4494800.html
> Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
>
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