Handle EOFs in the repl

This way whenever ^D is typed at the repl, the program gracefully
terminates and prints out the complete module.

diff --git a/Main.hs b/Main.hs
index cf20ab898fa2bd9744d698f29ee8dffea73b1bfe..f32003bdd2dbb48eba325526bf1849444fd1d09d 100644 (file)
--- a/Main.hs
+++ b/Main.hs
@@ -15,21 +15,29 @@ import LLVM.AST.Type as Type
 import LLVM.IRBuilder
 import LLVM.Pretty
 import System.IO
+import System.IO.Error
 import Text.Read (readMaybe)
 
-main = buildModuleT "main" repl
+main :: IO ()
+main = buildModuleT "main" repl >>= Text.hPutStrLn stderr . ("\n" <>) . ppll
 
 repl :: ModuleBuilderT IO ()
 repl = do
   liftIO $ hPutStr stderr "ready> "
-  ast <- liftIO $ readMaybe <$> getLine
-  case ast of
+  mline <- liftIO $ catchIOError (Just <$> getLine) eofHandler
+  case mline of
+    Nothing -> return ()
+    Just l -> do
+      case readMaybe l of
         Nothing ->  liftIO $ hPutStrLn stderr "Couldn't parse"
-    Just x -> do
-      hoist $ buildAST x
+        Just ast -> do
+          hoist $ buildAST ast
           mostRecentDef >>= liftIO . Text.hPutStrLn stderr . ppll
       repl
   where
+    eofHandler e
+      | isEOFError e = return Nothing
+      | otherwise = ioError e
 
 type Binds = Map.Map String Operand