integrating flymake.

Check.hs

@@ -0,0 +1,25 @@
+module Check (checkSyntax) where
+
+import Control.Applicative
+import Data.Char
+import Data.List
+import System.IO
+import System.Process
+
+----------------------------------------------------------------
+
+checkSyntax :: String -> IO String
+checkSyntax file = do
+    (_,_,herr,_) <- runInteractiveProcess "ghc" ["--make","-Wall",file] Nothing Nothing
+    refine <$> hGetContents herr
+  where
+   refine = unfoldLines start . map (dropWhile isSpace) . filter (/="") . lines
+   start = (file `isPrefixOf`)
+
+unfoldLines :: (String -> Bool) -> [String] -> String
+unfoldLines p = drop 1 . unfold
+  where
+    unfold [] = "\n"
+    unfold (l:ls)
+      | p l       = ('\n':l) ++ unfold ls
+      | otherwise = l ++ " " ++ unfold ls