From eec77f103115b92230af6d1b43ea1f2b58db28b8 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Wed, 23 Feb 2022 20:00:10 +0100
Subject: Error reporting

---
 src/Fun/Compiler.hs | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

(limited to 'src/Fun/Compiler.hs')

diff --git a/src/Fun/Compiler.hs b/src/Fun/Compiler.hs
index 5ceb967..a8134ed 100644
--- a/src/Fun/Compiler.hs
+++ b/src/Fun/Compiler.hs
@@ -3,12 +3,21 @@ module Fun.Compiler where
 import           Control.Exception
 import           Fun.Parser
 import           Fun.Tree
+import           System.Exit
+import           System.IO
+
+genTrace :: [String] -> String
+genTrace xs =
+  "Trace of expectance: "
+    ++ foldr (\a b -> a ++ if b == "" then b else " -> " ++ b) "" xs
 
 parse :: String -> Either String Program -- TODO: Should be tree
 parse file = case program file of
-  Left a -> Left $ "Invalid code around here:\n" ++ case a of
-    Nothing  -> "[No context]"
-    Just str -> str
+  Left a -> Left $ "Parse fault!\n" ++ case a of
+    State [] Nothing    -> "No context available"
+    State t  Nothing    -> genTrace t
+    State [] (Just str) -> "Around here:\n" ++ str
+    State t  (Just str) -> genTrace t ++ "\nAround here:\n" ++ str
   Right (a, b) -> Right a
 
 compile :: String -> IO ()
@@ -17,5 +26,7 @@ compile path = do
   case file of
     Left  exception -> print (exception :: IOError)
     Right file      -> case parse file of
-      Left  err   -> putStrLn err
+      Left err -> do
+        hPutStrLn stderr err
+        exitWith (ExitFailure 1)
       Right block -> putStrLn . show $ block
-- 
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