#2653: Hugs does not like bracketOnError in Network.hs
---------------------------------+------------------------------------------
Reporter: golubovsky | Owner:
Type: bug | Status: new
Priority: normal | Component: libraries/network
Version: 6.8.3 | Severity: major
Keywords: | Testcase:
Architecture: Unknown/Multiple | Os: Unknown/Multiple
---------------------------------+------------------------------------------
Currently network/Network.hs has this:
{{{
-- Utils
#if __GLASGOW_HASKELL__ < 606
-- Like bracket, but only performs the final action if there was an
-- exception raised by the middle bit.
bracketOnError
:: IO a -- ^ computation to run first (\"acquire
resource\")
-> (a -> IO b) -- ^ computation to run last (\"release
resource\")
-> (a -> IO c) -- ^ computation to run in-between
-> IO c -- returns the value from the in-between
computation
bracketOnError before after thing =
Exception.block (do
a <- before
r <- Exception.catch
(Exception.unblock (thing a))
(\e -> do { after a; Exception.throw e })
return r
)
#else
bracketOnError = Exception.bracketOnError
#endif
}}}
So Hugs gets the <606 definition which it does not like (type error
printed on bracketOnError).
{{{
runhugs: Error occurred
ERROR "/home2/dima/install/hugs98/hugsdir/packages/network/Network.hs":511
- Cannot justify constraints in explicitly typed binding
*** Expression : bracketOnError
*** Type : IO a -> (a -> IO b) -> (a -> IO c) -> IO c
*** Given context : ()
*** Constraints : Exception d
}}}
This can be fixed by adding `&& !__HUGS__` to the #if line.
That is (darcs whatsnew),
{{{
{
hunk ./Network.hs 378
-#if __GLASGOW_HASKELL__ < 606
+#if __GLASGOW_HASKELL__ < 606 && !__HUGS__
}
}}}
so Hugs gets the second definition (redirected to
Exception.bracketOnError) which works.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2653>
GHC <http://www.haskell.org/ghc/>
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