Instances.hs

------------------------------------------------------------------------------
-- CPP macros for common instances
------------------------------------------------------------------------------

-- XXX use template haskell instead and include Monoid and IsStream instances
-- as well.

#define MONADPARALLEL , MonadAsync m

#define MONAD_APPLICATIVE_INSTANCE(STREAM,CONSTRAINT)         \
instance (Monad m CONSTRAINT) => Applicative (STREAM m) where { \
    pure = STREAM . K.yield;                     \
    (<*>) = ap }

#define MONAD_COMMON_INSTANCES(STREAM,CONSTRAINT)                            \
instance Monad m => Functor (STREAM m) where { \
    fmap = map };                                                             \
                                                                              \
instance (MonadBase b m, Monad m CONSTRAINT) => MonadBase b (STREAM m) where {\
    liftBase = liftBaseDefault };                                             \
                                                                              \
instance (MonadIO m CONSTRAINT) => MonadIO (STREAM m) where {                 \
    liftIO = lift . liftIO };                                                 \
                                                                              \
instance (MonadThrow m CONSTRAINT) => MonadThrow (STREAM m) where {           \
    throwM = lift . throwM };                                                 \
                                                                              \
{- \
instance (MonadError e m CONSTRAINT) => MonadError e (STREAM m) where {       \
    throwError = lift . throwError;                                           \
    catchError m h =                                                          \
        fromStream $ withCatchError (toStream m) (\e -> toStream $ h e) };  \
-} \
                                                                              \
instance (MonadReader r m CONSTRAINT) => MonadReader r (STREAM m) where {     \
    ask = lift ask;                                                           \
    local f m = fromStream $ K.withLocal f (toStream m) };                    \
                                                                              \
instance (MonadState s m CONSTRAINT) => MonadState s (STREAM m) where {       \
    get     = lift get;                                                       \
    put x   = lift (put x);                                                   \
    state k = lift (state k) }