Unable to use Servant.RawM based on documentation examples

[saurabhnanda]

Hi, I'm trying to write a raw webhook endpoint due to this complication in the Accept header. Here's what I've got:

data Env = Env {..} -- my application's reader environment
type AppM = ReaderT Env IO

type Routes = "lambda" :> "webhook" :> RawM

server :: ServerT Routes AppM
server = saveWebhookPayload

saveWebhookPayload :: AppM Wai.Application
saveWebhookPayload = do
  env_ <- getEnv
  pure $ \req respond -> do
     -- my Wai application here that uses the env_

I'm getting the following compiler error:

    • Couldn't match type ‘ServerT (RawM' FileServer) (ReaderT Env IO)’
                     with ‘ReaderT Env IO Application’
      Expected type: ServerT Routes AppM
        Actual type: AppM Application
    • In the expression: saveWebhookPayload
      In an equation for ‘server’: server = saveWebhookPayload

What am I doing wrong? Is this supposed to be used only for static file serving?