reddit-pub/reddit_tags/src/MyLib.hs

{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}
module MyLib (someFunc) where
import System.Environment (lookupEnv)
import Control.Monad.Trans.Maybe (MaybeT(..))
import Network.AMQP
import qualified Data.Text as T
import Data.Text (Text)
import Control.Exception (bracket)
import Control.Concurrent (newEmptyMVar, readMVar)
import Control.Monad (void)

data AMQP = AMQP
  { host :: String
  , vhost :: Text
  , username :: Text
  , password :: Text
  }

getAMQP :: IO (Maybe AMQP)
getAMQP = runMaybeT $
  AMQP <$> lookupEnvM "AMQP_HOST" <*> lookupEnvMText "AMQP_VHOST" <*> lookupEnvMText "AMQP_USER" <*> lookupEnvMText "AMQP_PASS"
  where
    lookupEnvM = MaybeT . lookupEnv
    lookupEnvMText = fmap T.pack . lookupEnvM

someFunc :: IO ()
someFunc = do
  Just AMQP{..} <- getAMQP
  let rabbitConnect = openConnection host vhost username password
  bracket rabbitConnect closeConnection $ \conn -> do
    chan <- openChannel conn
    qos chan 0 1 False
    declareQueue chan newQueue {queueName="reddit_tags"}
    bindQueue chan "reddit_tags" "reddit_posts" "key"
    consumeMsgs chan "reddit_tags" Ack $ \(msg, env) -> do
      print msg
      ackEnv env
    void getLine