New subject: Derving NFData via Generics from a type that has a vector doesn't work. (was trying to understand out of memory exceptions)

16 Apr 2013


      -- ok, something in deriving NFData using Generics in a type that has a
Vector in it.


{-# LANGUAGE DeriveGeneric #-}
import Control.DeepSeq
import System.IO
import GHC.Generics (Generic)
import qualified Data.Vector as V
import qualified Data.ByteString.Lazy.Char8 as BL

scanl' :: NFData a => (a -> b -> a) -> a -> [b] -> [a]
scanl' f q ls =  q : (case ls of
                        []   -> []
                        x:xs -> let q' = f q x
                                in q' `deepseq` scanl' f q' xs)

-- this runs without blowing up
-- main = print $ last $ scanl' (+) (0::Int) [0..]

data Simple = Simple (V.Vector Double)
            deriving (Show, Generic)

instance NFData Simple

--this blows up
main = do
   let initial = Simple $ V.fromList (take 100 $ repeat 0)
       sumvs (Simple a) (Simple b) = Simple $ V.zipWith (+) a b
   print $ last $ scanl' sumvs initial $ repeat $ initial

Derving NFData via Generics from a type that has a vector doesn't work. (was trying to understand out of memory exceptions)

Anatoly Yakovenko

José Pedro Magalhães

anatoly yakovenko

Anatoly Yakovenko

Andres Löh

anatoly yakovenko

anatoly yakovenko

Andres Löh

anatoly yakovenko

tags

participants (4)