You're right.
The issue you've mentioned can be fixed easily - import Data.Generics
instead of Generics and get rid of -package lang (I've copied them from
the documentation without checking, seems like it's a bit outdated).
The real problem is that you can't use "Get a" in generics! And you have
the same problem here, because "Get" constructor isn't exported either!
But we can make it work using a continuation trick:
{-# OPTIONS_GHC -fglasgow-exts -XGenerics #-}
module Test where
import Control.Monad
import Data.Binary
import Data.Generics
import Data.Int
import System.Random
class Binary' a where
put' :: a -> Put
get' :: (a -> Get StdGen) -> Get StdGen
put' {| Unit |} Unit = return ()
get' {| Unit |} f = f Unit
put' {| a :+: b |} (Inl x) = putWord8 0 >> put' x
put' {| a :+: b |} (Inr y) = putWord8 1 >> put' y
get' {| a :+: b |} f =
do w <- getWord8
case w of
0 -> get' $ \x -> f $ Inl x
_ -> get' $ \y -> f $ Inr y
put' {| a :*: b |} (x :*: y) = put' x >> put' y
get' {| a :*: b |} f = get' $ \x -> get' $ \y -> f (x :*: y)
instance Binary' Int32 where
put' = put
get' f = get >>= f
instance Binary' StdGen
instance Binary StdGen where
put = put'
get = get' return
This time I've checked that it really compiles. Pretty much sure it works.
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