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|
{-# LANGUAGE StandaloneDeriving, DeriveGeneric #-}
module GHC.Data.SizedSeq
( SizedSeq(..)
, emptySS
, addToSS
, addListToSS
, ssElts
, sizeSS
) where
import Prelude -- See note [Why do we import Prelude here?]
import Control.DeepSeq
import Data.Binary
import Data.List
import GHC.Generics
data SizedSeq a = SizedSeq {-# UNPACK #-} !Word [a]
deriving (Generic, Show)
instance Functor SizedSeq where
fmap f (SizedSeq sz l) = SizedSeq sz (fmap f l)
instance Foldable SizedSeq where
foldr f c ss = foldr f c (ssElts ss)
instance Traversable SizedSeq where
traverse f (SizedSeq sz l) = SizedSeq sz . reverse <$> traverse f (reverse l)
instance Binary a => Binary (SizedSeq a)
instance NFData a => NFData (SizedSeq a) where
rnf (SizedSeq _ xs) = rnf xs
emptySS :: SizedSeq a
emptySS = SizedSeq 0 []
addToSS :: SizedSeq a -> a -> SizedSeq a
addToSS (SizedSeq n r_xs) x = SizedSeq (n+1) (x:r_xs)
addListToSS :: SizedSeq a -> [a] -> SizedSeq a
addListToSS (SizedSeq n r_xs) xs
= SizedSeq (n + genericLength xs) (reverse xs ++ r_xs)
ssElts :: SizedSeq a -> [a]
ssElts (SizedSeq _ r_xs) = reverse r_xs
sizeSS :: SizedSeq a -> Word
sizeSS (SizedSeq n _) = n
|
