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Sos!
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{-
Hi,
Possible Concurrent Haskell bug
Here is an attempt at concurrent, data-driven assertions for Haskell.
The code has been simplified to just work for type Char:
-}
import Concurrent
import IOExts(unsafePerformIO)
assert :: (Char -> Bool) -> Char -> Char
assert p x = unsafePerformIO $ do
mv <- newEmptyMVar
forkIO $ check p (listen mv)
return (demand mv x)
check :: (a -> Bool) -> a -> IO ()
check p x
| p x = return ()
| otherwise = putStrLn "Assertion failed!"
demand :: MVar Char -> Char -> Char
demand mv c = unsafePerformIO $ do putMVar mv c; yield; return c
listen :: MVar Char -> Char
listen mv = unsafePerformIO $ takeMVar mv
main :: IO ()
(Continue reading)
Here's a (serious) bug in the type-inferencer of the November 2002 Hugs (tested
using hugs98-Nov2002-rh7.3-1.i386.rpm):
data T a b = T {f1 :: a, f2 :: b}
updateF1 x t = t{f1 = x}
the type inferred for updateF1:
observed behavior:
updateF1 :: a -> T b c -> T a d
expected behavior:
updateF1 :: a -> T b c -> T a c
FYI, this bug didn't exist in the Dec 2001 version.
- Mark
On Wednesday, March 5, 2003, at 05:00 PM, Mark Tullsen wrote:
> Here's a (serious) bug in the type-inferencer of the November 2002
> Hugs (tested
> using hugs98-Nov2002-rh7.3-1.i386.rpm):
>
> data T a b = T {f1 :: a, f2 :: b}
> updateF1 x t = t{f1 = x}
>
> the type inferred for updateF1:
> observed behavior:
> updateF1 :: a -> T b c -> T a d
> expected behavior:
> updateF1 :: a -> T b c -> T a c
>
> FYI, this bug didn't exist in the Dec 2001 version.
>
Mark:
Slurp in a fresh version from CVS. I suspect that's the bug I
introduced, and was kindly spotted and fixed by Ross Patterson.
--Jeff
L.S., The web page http://cvs.haskell.org/Hugs/pages/hugsman/libs.html states: The libraries Directory, Time, and CPUTime, are not currently supported. As there are files Directory.hs, Time.hs, and CPUTime.hs in the {Hugs}\lib directory, I suppose this is not true anymore. Greetings, Henk-Jan van Tuyl -- --
With the following code
> run f = f 7 (-3)
> programError wd initVal = (if initVal < 0 then showAsUnsiged else const show) wd initVal
> noProblem wd initVal = f wd initVal where f = if initVal < 0 then showAsUnsiged else const show
> showAsUnsiged width nIn = show n where n | nIn < 0 = 2^width + nIn
> | otherwise = nIn
I get:
$ hugs HugsIfFuncBug.lhs
__ __ __ __ ____ ___ _________________________________________
|| || || || || || ||__ Hugs 98: Based on the Haskell 98 standard
||___|| ||__|| ||__|| __|| Copyright (c) 1994-2002
||---|| ___|| World Wide Web: http://haskell.org/hugs
|| || Report bugs to: hugs-bugs <at> haskell.org
|| || Version: November 2002 _________________________________________
Haskell 98 mode: Restart with command line option -98 to enable extensions
Reading file "/usr/lib/hugs/libraries/Hugs/Prelude.hs":
Reading file "/usr/lib/hugs/libraries/Prelude.hs":
Reading file "HugsIfFuncBug.lhs":
Hugs session for:
/usr/lib/hugs/libraries/Hugs/Prelude.hs
/usr/lib/hugs/libraries/Prelude.hs
(Continue reading)
I'm using :version -- Hugs Version November 2002 If I make a .hs file with the two lines: import Maybe Need. And do a :load IE.hs, the output is Reading file "IE.hs": Reading file "/usr/local/lib/hugs/lib/Maybe.hs": Reading file "IE.hs": INTERNAL ERROR: parseInput
I tried to run a program that imports SOEGraphics, and I got this error message when hugs tried to read MarshalUtils.hs: "Reading file ... ... Reading file "C:\Program Files\Hugs98\lib\exts\MarshalUtils.hs": Parsing ERROR "C:\Program Files\Hugs98\lib\exts\MarshalUtils.hs":2 - Syntax error in module definition (unexpected keyword "with"; possible cause: -W option not used.) " FYI, I am using WinXP. -- -- __________________________________________________________ Sign-up for your own FREE Personalized E-mail at Mail.com http://www.mail.com/?sr=signup
Your mail to 'Hugs-Users' with the subject
A very new website
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The following module is accepted by ghc (with -fglasgow-exts) but
rejected by hugs:
module ParseAny where
class Syntax tag as | tag -> as where
parse :: tag -> String -> as
data AnyAs = forall tag as. Syntax tag as =>
MkAs tag as
data AnyTag = forall tag as. Syntax tag as =>
MkTag tag
parseAny :: AnyTag -> String -> AnyAs
parseAny (MkTag tag) str = MkAs tag $ parse tag str
-- -------------------------------------------------------
Hugs mode: Restart with command line option +98 for Haskell 98 mode
Reading file "/home/linux-bkb/hugs/lib/hugs/libraries/Hugs/Prelude.hs":
Reading file "/home/linux-bkb/hugs/lib/hugs/libraries/Prelude.hs":
Reading file "ParseAny.hs":
Type checking
ERROR "ParseAny.hs":13 - Cannot justify constraints in explicitly typed
binding
*** Expression : parseAny
*** Type : AnyTag -> String -> AnyAs
*** Given context : ()
(Continue reading)
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