Further library additions and REPL updates

src/Main.hs

@@ -11,7 +11,11 @@ import qualified Data.Map as Map
 import Text.Megaparsec (runParser)
 
 main :: IO ()
-main = repl library
+main = do
+  putStrLn "Welcome to the Sapling Interpreter"
+  putStrLn "You can exit at any time by typing and entering: "
+  putStrLn ":_exit"
+  repl library
 
 runSapling :: String -> String
 runSapling s = show $ result (evalSapling Map.empty $ parseSapling s)