{-| Module : Debug.Hoed.Pure Description : Lighweight algorithmic debugging based on observing intermediate values. Copyright : (c) 2000 Andy Gill, (c) 2010 University of Kansas, (c) 2013-2015 Maarten Faddegon License : BSD3 Maintainer : hoed@maartenfaddegon.nl Stability : experimental Portability : POSIX Hoed is a tracer and debugger for the programming language Haskell. Hoed.Pure is recommended over Hoed.Stk: in contrast to Hoed.Stk you can optimize your program and do not need to enable profiling when using Hoed.Pure. To locate a defect with Hoed.Pure you annotate suspected functions and compile as usual. Then you run your program, information about the annotated functions is collected. Finally you connect to a debugging session using a webbrowser. Let us consider the following program, a defective implementation of a parity function with a test property. > import Test.QuickCheck > > isOdd :: Int -> Bool > isOdd n = isEven (plusOne n) > > isEven :: Int -> Bool > isEven n = mod2 n == 0 > > plusOne :: Int -> Int > plusOne n = n + 1 > > mod2 :: Int -> Int > mod2 n = div n 2 > > prop_isOdd :: Int -> Bool > prop_isOdd x = isOdd (2*x+1) > > main :: IO () > main = printO (prop_isOdd 1) > > main :: IO () > main = quickcheck prop_isOdd Using the property-based test tool QuickCheck we find the counter example `1` for our property. > ./MyProgram > *** Failed! Falsifiable (after 1 test): 1 Hoed can help us determine which function is defective. We annotate the functions `isOdd`, `isEven`, `plusOne` and `mod2` as follows: > import Debug.Hoed.Pure > > isOdd :: Int -> Bool > isOdd = observe "isOdd" isOdd' > isOdd' n = isEven (plusOne n) > > isEven :: Int -> Bool > isEven = observe "isEven" isEven' > isEven' n = mod2 n == 0 > > plusOne :: Int -> Int > plusOne = observe "plusOne" plusOne' > plusOne' n = n + 1 > > mod2 :: Int -> Int > mod2 = observe "mod2" mod2' > mod2' n = div n 2 > > prop_isOdd :: Int -> Bool > prop_isOdd x = isOdd (2*x+1) > > main :: IO () > main = printO (prop_isOdd 1) After running the program a computation tree is constructed and displayed in a web browser. > ./MyProgram > False > Listening on http://127.0.0.1:10000/ After running the program a computation tree is constructed and displayed in a web browser. You can freely browse this tree to get a better understanding of your program. If your program misbehaves, you can judge the computation statements in the tree as 'right' or 'wrong' according to your intention. When enough statements are judged the debugger tells you the location of the fault in your code. <> Read more about Hoed on its project homepage . Papers on the theory behind Hoed can be obtained via . I am keen to hear about your experience with Hoed: where did you find it useful and where would you like to see improvement? You can send me an e-mail at hoed@maartenfaddegon.nl, or use the github issue tracker . -} {-# LANGUAGE CPP #-} module Debug.Hoed.Pure ( -- * Basic annotations observe , runO , printO , testO -- * Property-assisted algorithmic debugging , runOwp , testOwp , Propositions(..) , PropType(..) , Proposition(..) , PropositionType(..) , Module(..) , Signature(..) , ParEq(..) , runOstore , conAp -- * Build your own debugger with Hoed , runO' , judge , unjudgedCharacterCount , CompTree(..) , Vertex(..) , CompStmt(..) , Judge(..) , Verbosity(..) -- * Alternative template Haskell annotations , observeTempl , observedTypes -- * API to test Hoed itself , logO , logOwp , traceOnly , UnevalHandler(..) -- * The Observable class , Observer(..) , Observable(..) , (<<) , thunk , nothunk , send , observeOpaque , observeBase , constrainBase , debugO , CDS(..) , Generic ) where import Debug.Hoed.Pure.Observe import Debug.Hoed.Pure.Render import Debug.Hoed.Pure.EventForest import Debug.Hoed.Pure.CompTree import Debug.Hoed.Pure.DemoGUI import Debug.Hoed.Pure.Prop import Debug.Hoed.Pure.Serialize import Paths_Hoed(getDataDir) import Prelude hiding (Right) import qualified Prelude import System.Process(system) import System.IO import Data.Maybe import Control.Monad import Data.List import Data.Ord import Data.Char import System.Environment import System.Directory(createDirectoryIfMissing) import Language.Haskell.TH import GHC.Generics import Data.IORef import System.IO.Unsafe import Data.Graph.Libgraph import Graphics.UI.Threepenny(startGUI,defaultConfig,Config(..)) import System.Directory(createDirectoryIfMissing) -- %************************************************************************ -- %* * -- \subsection{External start functions} -- %* * -- %************************************************************************ -- Run the observe ridden code. runOnce :: IO () runOnce = do f <- readIORef firstRun case f of True -> writeIORef firstRun False False -> error "It is best not to run Hoed more that once (maybe you want to restart GHCI?)" firstRun :: IORef Bool firstRun = unsafePerformIO $ newIORef True -- | run some code and return the Trace debugO :: IO a -> IO Trace debugO program = do { runOnce ; initUniq ; startEventStream ; let errorMsg e = "[Escaping Exception in Code : " ++ show e ++ "]" ; ourCatchAllIO (do { program ; return () }) (hPutStrLn stderr . errorMsg) ; endEventStream } -- | The main entry point; run some IO code, and debug inside it. -- After the IO action is completed, an algorithmic debugging session is started at -- @http://localhost:10000/@ to which you can connect with your webbrowser. -- -- For example: -- -- @ -- main = runO $ do print (triple 3) -- print (triple 2) -- @ runO :: IO a -> IO () runO program = do (trace,traceInfo,compTree,frt) <- runO' Verbose program debugSession trace traceInfo compTree frt [] return () -- | Hoed internal function that stores a serialized version of the tree on disk (assisted debugging spawns new instances of Hoed). runOstore :: String -> IO a -> IO () runOstore tag program = do (trace,traceInfo,compTree,frt) <- runO' Silent program storeTree (treeFilePath ++ tag) compTree storeTrace (traceFilePath ++ tag) trace -- | Repeat and trace a failing testcase testO :: Show a => (a->Bool) -> a -> IO () testO p x = runO $ putStrLn $ if (p x) then "Passed 1 test." else " *** Failed! Falsifiable: " ++ show x -- | Use property based judging. runOwp :: [Propositions] -> IO a -> IO () runOwp ps program = do (trace,traceInfo,compTree,frt) <- runO' Verbose program let compTree' = compTree debugSession trace traceInfo compTree' frt ps return () -- | Repeat and trace a failing testcase testOwp :: Show a => [Propositions] -> (a->Bool) -> a -> IO () testOwp ps p x = runOwp ps $ putStrLn $ if (p x) then "Passed 1 test." else " *** Failed! Falsifiable: " ++ show x -- | Short for @runO . print@. printO :: (Show a) => a -> IO () printO expr = runO (print expr) -- | Only produces a trace. Useful for performance measurements. traceOnly :: IO a -> IO () traceOnly program = do debugO program return () data Verbosity = Verbose | Silent condPutStrLn :: Verbosity -> String -> IO () condPutStrLn Silent _ = return () condPutStrLn Verbose msg = hPutStrLn stderr msg -- |Entry point giving you access to the internals of Hoed. Also see: runO. runO' :: Verbosity -> IO a -> IO (Trace,TraceInfo,CompTree,EventForest) runO' verbose program = do createDirectoryIfMissing True ".Hoed/" condPutStrLn verbose "=== program output ===\n" events <- debugO program condPutStrLn verbose"\n=== program terminated ===" condPutStrLn verbose"Please wait while the computation tree is constructed..." let cdss = eventsToCDS events let cdss1 = rmEntrySet cdss let cdss2 = simplifyCDSSet cdss1 let eqs = renderCompStmts cdss2 let frt = mkEventForest events ti = traceInfo (reverse events) ds = dependencies ti ct = mkCompTree eqs ds writeFile ".Hoed/Events" (unlines . map show . reverse $ events) #if defined(TRANSCRIPT) writeFile ".Hoed/Transcript" (getTranscript events ti) #endif condPutStrLn verbose "\n=== Statistics ===\n" let e = length events n = length eqs b = fromIntegral (length . arcs $ ct ) / fromIntegral ((length . vertices $ ct) - (length . leafs $ ct)) condPutStrLn verbose $ show e ++ " events" condPutStrLn verbose $ show n ++ " computation statements" condPutStrLn verbose $ show ((length . vertices $ ct) - 1) ++ " nodes + 1 virtual root node in the computation tree" condPutStrLn verbose $ show (length . arcs $ ct) ++ " edges in computation tree" condPutStrLn verbose $ "computation tree has a branch factor of " ++ show b ++ "(i.e the average number of children of non-leaf nodes)" condPutStrLn verbose "\n=== Debug Session ===\n" return (events, ti, ct, frt) -- | Trace and write computation tree to file. Useful for regression testing. logO :: FilePath -> IO a -> IO () logO filePath program = {- SCC "logO" -} do (_,_,compTree,_) <- runO' Verbose program writeFile filePath (showGraph compTree) return () where showGraph g = showWith g showVertex showArc showVertex RootVertex = ("\".\"","shape=none") showVertex v = ("\"" ++ (escape . showCompStmt) v ++ "\"", "") showArc _ = "" showCompStmt = show . vertexStmt -- | As logO, but with property-based judging. logOwp :: UnevalHandler -> FilePath -> [Propositions] -> IO a -> IO () logOwp handler filePath properties program = do (trace,traceInfo,compTree,frt) <- runO' Verbose program hPutStrLn stderr "\n=== Evaluating assigned properties ===\n" compTree' <- judgeAll handler unjudgedCharacterCount trace properties compTree writeFile filePath (showGraph compTree') return () where showGraph g = showWith g showVertex showArc showVertex RootVertex = ("root","") showVertex v = ("\"" ++ (escape . showCompStmt) v ++ "\"", "") showArc _ = "" showCompStmt s = (show . vertexJmt) s ++ ": " ++ (show . vertexStmt) s ------------------------------------------------------------------------ -- Algorithmic Debugging debugSession :: Trace -> TraceInfo -> CompTree -> EventForest -> [Propositions] -> IO () debugSession trace traceInfo tree frt ps = do createDirectoryIfMissing True ".Hoed/wwwroot/css" dataDir <- getDataDir system $ "cp " ++ dataDir ++ "/img/*png .Hoed/wwwroot/" system $ "cp " ++ dataDir ++ "/img/*gif .Hoed/wwwroot/" startGUI defaultConfig { jsPort = Just 10000 , jsStatic = Just "./.Hoed/wwwroot" } (guiMain trace tree frt ps)