Fixes identifier lexing; support REPL file loading

src/REPL.hs

@@ -1,6 +1,7 @@
 module REPL where
 
 import Eval
+import FileEval
 import Lexer
 import Parser
 import Research
@@ -21,6 +22,15 @@ repl env = runInputT defaultSettings (loop env)
       case minput of
         Nothing -> outputStrLn "Goodbye!"
         Just ":_exit" -> outputStrLn "Goodbye!"
+        Just ":_load" -> do
+          path <- getInputLine "File path to load < "
+          case path of
+            Nothing -> do
+              outputStrLn "No input received; stopping import."
+              loop env
+            Just path -> do
+              loadedEnv <- liftIO $ evaluateFileEnv path
+              loop $ Map.union loadedEnv env
         Just "" -> do
           outputStrLn ""
           loop env