Prevent the REPL from grabbing and printing exceptions it should

be leaving alone (async and exit exceptions).

saw/SAWScript/REPL/Command.hs

@@ -39,7 +39,9 @@ import SAWScript.Position (getPos)
 import Cryptol.Parser (ParseError())
 import Cryptol.Utils.PP hiding ((</>))
 
+import Control.Exception (displayException)
 import Control.Monad (guard)
+
 import Data.Char (isSpace,isPunctuation,isSymbol)
 import Data.Function (on)
 import Data.List (intercalate)
@@ -146,7 +148,7 @@ runCommand c = case c of
                      `SAWScript.REPL.Monad.catchOther` handlerPrint
     where
     handlerPP re = io (putStrLn "" >> print (pp re))
-    handlerPrint e = io (putStrLn "" >> print e)
+    handlerPrint e = io (putStrLn "" >> putStrLn (displayException e))
     handlerFail s = io (putStrLn "" >> putStrLn s)
 
   Unknown cmd -> io (putStrLn ("Unknown command: " ++ cmd))

saw/SAWScript/REPL/Monad.hs

@@ -8,6 +8,7 @@ Stability   : provisional
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE PatternGuards #-}
 {-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
 
 module SAWScript.REPL.Monad (
@@ -76,6 +77,7 @@ import Data.Typeable (Typeable)
 import System.Console.ANSI (setTitle)
 import qualified Control.Exception as X
 import System.IO.Error (isUserError, ioeGetErrorString)
+import System.Exit (ExitCode)
 
 import Verifier.SAW.SharedTerm (Term)
 import Verifier.SAW.CryptolEnv
@@ -238,9 +240,14 @@ catchFail m k = REPL (\ ref -> X.catchJust sel (unREPL m ref) (\s -> unREPL (k s
     sel e | isUserError e = Just (ioeGetErrorString e)
           | otherwise     = Nothing
 
--- | Handle any other exception
+-- | Handle any other exception (except that we ignore async exceptions and exitWith)
 catchOther :: REPL a -> (X.SomeException -> REPL a) -> REPL a
-catchOther = catchEx
+catchOther m k = REPL (\ref -> X.catchJust flt (unREPL m ref) (\s -> unREPL (k s) ref))
+ where
+  flt e
+    | Just (_ :: X.AsyncException) <- X.fromException e = Nothing
+    | Just (_ :: ExitCode)       <- X.fromException e = Nothing
+    | otherwise = Just e
 
 rethrowEvalError :: IO a -> IO a
 rethrowEvalError m = run `X.catch` rethrow