Split the code into library and application

lib/SlackBuilder/Trans.hs

@@ -0,0 +1,29 @@
+module SlackBuilder.Trans
+    ( SlackBuilderT(..)
+    ) where
+
+import Control.Monad.Trans.Reader (ReaderT(..))
+import SlackBuilder.Config
+import Control.Monad.IO.Class (MonadIO(..))
+
+newtype SlackBuilderT a = SlackBuilderT
+    { runSlackBuilderT :: ReaderT Settings IO a
+    }
+
+instance Functor SlackBuilderT
+  where
+    fmap f (SlackBuilderT slackBuilderT) = SlackBuilderT $ f <$> slackBuilderT
+
+instance Applicative SlackBuilderT
+  where
+    pure = SlackBuilderT . pure
+    (SlackBuilderT f) <*> (SlackBuilderT x) = SlackBuilderT $ f <*> x
+
+instance Monad SlackBuilderT
+  where
+    return = pure
+    (SlackBuilderT x) >>= f = SlackBuilderT $ x >>= runSlackBuilderT . f
+
+instance MonadIO SlackBuilderT
+  where
+    liftIO = SlackBuilderT . liftIO