forgot I added a file

app/Logger.hs

@@ -0,0 +1,76 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Logger (Logger (logError, logWarning, logInfo, logDebug)) where
+
+import Control.Monad.Trans.Class (MonadTrans (lift))
+import Control.Monad.Trans.State (StateT, modify)
+import Control.Monad.Trans.Writer (WriterT, tell)
+import Data.Functor.Identity (Identity)
+import qualified Data.Text as T
+import qualified Data.Text.IO as T
+import Development.Shake (Action)
+import qualified Development.Shake as Shake
+
+class (Monad m) => Logger m where
+  logError :: T.Text -> m ()
+  logWarning :: T.Text -> m ()
+  logInfo :: T.Text -> m ()
+  logDebug :: T.Text -> m ()
+
+logIO :: T.Text -> IO ()
+logIO = T.putStrLn
+
+instance Logger IO where
+  logError = logIO
+  logWarning = logIO
+  logInfo = logIO
+  logDebug = logIO
+
+logState :: (Monad m) => T.Text -> StateT T.Text m ()
+logState msg = modify (\log -> log <> msg <> "\n")
+
+instance (Monad m) => Logger (StateT T.Text m) where
+  logError = logState
+  logWarning = logState
+  logInfo = logState
+  logDebug = logState
+
+logStateStr :: (Monad m) => T.Text -> StateT String m ()
+logStateStr msg = modify (\log -> log <> T.unpack msg <> "\n")
+
+instance (Monad m) => Logger (StateT String m) where
+  logError = logStateStr
+  logWarning = logStateStr
+  logInfo = logStateStr
+  logDebug = logStateStr
+
+instance (Monad m) => Logger (WriterT T.Text m) where
+  logError = tell . (<> "\n")
+  logWarning = tell . (<> "\n")
+  logInfo = tell . (<> "\n")
+  logDebug = tell . (<> "\n")
+
+instance (Monad m) => Logger (WriterT String m) where
+  logError = tell . T.unpack . (<> "\n")
+  logWarning = tell . T.unpack . (<> "\n")
+  logInfo = tell . T.unpack . (<> "\n")
+  logDebug = tell . T.unpack . (<> "\n")
+
+instance Logger Action where
+  logError = Shake.putError . T.unpack
+  logWarning = Shake.putWarn . T.unpack
+  logInfo = Shake.putInfo . T.unpack
+  logDebug = Shake.putLoud . T.unpack
+
+instance Logger Identity where
+  logError = const $ pure ()
+  logWarning = const $ pure ()
+  logInfo = const $ pure ()
+  logDebug = const $ pure ()
+
+-- this isn't strictly correct but it's only used for ParsecT so it is practically correct
+instance (MonadTrans mt, Logger m) => Logger (mt m) where
+  logError = lift . logError
+  logWarning = lift . logWarning
+  logInfo = lift . logInfo
+  logDebug = lift . logDebug