{-# LANGUAGE UndecidableInstances #-}

-- | silent logging (output nothing)
module Control.Carrier.Logging.Silent (SilentLoggingC (..)) where

import Control.Algebra (Algebra (alg), (:+:) (L, R))
import Control.Effect.Logging (Logging (LoggerLog))
import Control.Monad.Identity (IdentityT (IdentityT))
import UnliftIO (MonadIO, MonadUnliftIO)

-- | a sileng logging carrier, that doesn't print any logs
newtype SilentLoggingC m a = MkSilentLoggingC {runSilentLogging :: m a}
  deriving
    (Functor, Applicative, Monad, MonadIO, MonadFail, MonadUnliftIO)
    via IdentityT m

instance Algebra sig m => Algebra (Logging :+: sig) (SilentLoggingC m) where
  alg hdl sig ctx = case sig of
    L (LoggerLog _msg) -> MkSilentLoggingC (ctx <$ pure ())
    R other -> MkSilentLoggingC do
      alg (runSilentLogging . hdl) other ctx