Fix interpreter

src/Main.hs

@@ -1,8 +1,10 @@
 {-# LANGUAGE LambdaCase #-}
 module Main where
 
+import           Grammar.ErrM       (Err)
 import           Grammar.Par        (myLexer, pProgram)
 import           Grammar.Print      (printTree)
+import           Interpreter        (interpret)
 import           LambdaLifter       (abstract, freeVars, lambdaLift)
 import           System.Environment (getArgs)
 import           System.Exit        (exitFailure, exitSuccess)
@@ -10,20 +12,41 @@ import           System.Exit        (exitFailure, exitSuccess)
 main :: IO ()
 main = getArgs >>= \case
   []    -> print "Required file path missing"
-  (x:_) -> do
-    file <- readFile x
-    case pProgram (myLexer file) of
-      Left err -> do
-       putStrLn "SYNTAX ERROR"
-       putStrLn err
-       exitFailure
-      Right prg -> do
-        putStrLn "-- Parse"
-        putStrLn $ printTree prg
-        putStrLn "\n-- Lambda lifter"
-        putStrLn . printTree $ lambdaLift prg
-        putStrLn ""
-        exitSuccess
+  (s:_) -> main' s
+
+main' :: String -> IO ()
+main' s = do
+  file   <- readFile s
+
+  putStrLn "\n-- parse"
+  parsed    <- fromSyntaxErr . pProgram $ myLexer file
+  putStrLn $ printTree parsed
+
+  putStrLn "\n-- Lambda Lifter"
+  let lifted = lambdaLift parsed
+  putStrLn $ printTree lifted
+
+  interpred <- fromInterpreterErr $ interpret lifted
+  putStrLn "\n-- interpret"
+  print interpred
+
+  exitSuccess
 
 
+fromSyntaxErr :: Err a -> IO a
+fromSyntaxErr = either
+  (\err -> do
+    putStrLn "\nSYNTAX ERROR"
+    putStrLn err
+    exitFailure)
+ pure
+
+fromInterpreterErr :: Err a -> IO a
+fromInterpreterErr = either
+  (\err -> do
+    putStrLn "\nINTERPRETER ERROR"
+    putStrLn err
+    exitFailure)
+ pure
+