WrappingFail

WrappingFail.hs

data WrapperError = WrappingS3Error Jaws.S3Error
makeClassyPrisms ''WrapperError

instance Jaws.AsS3Error WrapperError where
  _S3Error = _WrappingS3Error

data Lookup m a = Lookup (m a)

inner
  :: ( AWS.MonadAWS m
     , MonadError e m
     , Jaws.AsS3Error e
     , MonadResource m
     )
  => Lookup m a
  -> m S3.GetObjectResponse
inner _ = Jaws.getObjectResponse "bucket" "key"

wrapper
  :: ( AWS.MonadAWS m
     , MonadError e m
     , AsWrapperError e
     , MonadResource m
     )
  => Lookup m a
  -> m S3.GetObjectResponse
wrapper lookup = do
  (e :: Either WrapperError S3.GetObjectResponse) <- runExceptT $ inner lookup
  either (throwing _WrappingError) pure e

error:
• Occurs check: cannot construct the infinite type:
m ~ ExceptT S3Error m
Expected type: ExceptT S3Error m S3.GetObjectResponse
Actual type: m S3.GetObjectResponse