- Glasgow-haskell-users

RE: -package-name
by Simon Marlow 14 Oct '02

14 Oct '02

> | Aha. So how will GHC find all the various module imports? > > You install the package using ghc-pkg. That tells GHC where it is. For more information on the interaction between hierarchical libraries and the package mechanism, see http://www.haskell.org/pipermail/glasgow-haskell-users/2002-September/00 4005.html Cheers, Simon

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RE: unsafePerformIO
by Simon Marlow 14 Oct '02

14 Oct '02

> [...] > > > > As for sharing, we currently don't provide any guarnatees, > although we > > should. It is currently the case that if you write > > > > a = unsafePerformIO (putStr "hello") > > b = unsafePerformIO (putStr "hello") > > > > and both a and b are evaluated, then you may get either one or two > > "hello"s on stdout. You can currently make things more > deterministic by > > (a) adding NOINLINE pragmas for a and b, and (b) using the > flag -fno-cse > > to disable common sub-expression elimination. Then you'll > get exactly > > two instances of "hello" on stdout, although we won't guarantee that > > behaviour for ever. At some point we'll fix it so that > unsafePerformIO > > applications are never duplicated or coalesced. > > > Are there any (short) examples available where using of > unsafePerformIO > leads to unexpected behaviour, > especially an example with the terms a and b from above? I don't have any examples to hand, but you ought to be able to make one up without too much difficulty. You just need two identical bindings such as in the example above, and compile with -O. Cheers, Simon

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Reviving GHC on Mac OS X 10.2 (Jaguar)
by Sébastien Carlier 13 Oct '02

13 Oct '02

Hi, The binary snapshot for Mac OS X on http://haskell.cs.yale.edu/ghc/ does not run on Jaguar. After looking into that a bit, I have found that just setting the following two environment variables solves the problem: > export DYLD_INSERT_LIBRARIES=/usr/lib/libtermcap.dylib > export DYLD_FORCE_FLAT_NAMESPACE=1 (I just found out about the version compiled for Jaguar at <http://www.uni-graz.at/imawww/haskell/JaguarGHC.tar.gz> but this trick might bu useful in the future if Apple split libraries again.) -- Sébastien

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Rts.h and C++ Annoyance
by Ashley Yakeley 13 Oct '02

13 Oct '02

It seems I can't compile Rts.h as C++ on Linux. Curiously it compiles OK on Darwin. $ gcc -x c -c /usr/lib/ghc-5.04/include/Rts.h $ gcc -x c++ -c /usr/lib/ghc-5.04/include/Rts.h In file included from /usr/lib/ghc-5.04/include/Stg.h:210, from /usr/lib/ghc-5.04/include/Rts.h:20: /usr/lib/ghc-5.04/include/gmp.h:1970: declaration of C function `class ostream & operator <<(ostream &, const __mpq_struct *)' conflicts with /usr/lib/ghc-5.04/include/gmp.h:1969: previous declaration `class ostream & operator <<(ostream &, const __mpz_struct *)' here /usr/lib/ghc-5.04/include/gmp.h:1971: declaration of C function `class ostream & operator <<(ostream &, const __mpf_struct *)' conflicts with /usr/lib/ghc-5.04/include/gmp.h:1970: previous declaration `class ostream & operator <<(ostream &, const __mpq_struct *)' here /usr/lib/ghc-5.04/include/gmp.h:1973: declaration of C function `class istream & operator >>(istream &, __mpq_struct *)' conflicts with /usr/lib/ghc-5.04/include/gmp.h:1972: previous declaration `class istream & operator >>(istream &, __mpz_struct *)' here /usr/lib/ghc-5.04/include/gmp.h:1974: declaration of C function `class istream & operator >>(istream &, __mpf_struct *)' conflicts with /usr/lib/ghc-5.04/include/gmp.h:1973: previous declaration `class istream & operator >>(istream &, __mpq_struct *)' here $ gcc --version 2.95.4 $ ghc --version The Glorious Glasgow Haskell Compilation System, version 5.04 $ uname -a Linux server 2.4.18-686 #1 Sun Apr 14 11:32:47 EST 2002 i686 unknown $ -- Ashley Yakeley, Seattle WA

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Save on Chipworks' Technical Publications - Limited Time Offer!
by Info 11 Oct '02

11 Oct '02

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RE: non-termination during compilation
by Simon Peyton-Jones 11 Oct '02

11 Oct '02

Yes, it's a known bug. GHC just inlines over and over again. It's discussed in "secrets of the GHC inliner". It's quite tiresome to fix without compromising something else, and I have never found a real program (rather than 'russel') that tickles the bug. I'd better document it, though Simon | -----Original Message----- | From: Christian Maeder [mailto:maeder@Informatik.Uni-Bremen.DE] | Sent: 10 October 2002 16:02 | To: glasgow-haskell-users(a)haskell.org | Subject: non-termination during compilation | | Hi, | | the following example causes ghc to loop (or run rather long): | | --- snip --- | | data U = MkU (U -> Bool) | | russel :: U -> Bool | russel u@(MkU p) = not $ p u | | x :: Bool | x = russel (MkU russel) | | --- snip --- | | I think, a compiler should always terminate, shouldn't it!? | | Compilation succeeds for "russel $ MkU russel" instead of "russel (MkU | russel)". | (Surely, x is bottom and therefore the example is senseless) | | Regards Christian | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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RE: brain explosion in polymorphic state monad
by Simon Peyton-Jones 11 Oct '02

11 Oct '02

Use 'case'. Instead of | let MkStateT m2 = k a | m2 s1 ) say case k a of MkStateT m2 -> m2 s1 Simon | -----Original Message----- | From: mathieu [mailto:tenfingers@ifrance.com] | Sent: 10 October 2002 21:42 | To: ghc users | Subject: brain explosion in polymorphic state monad | | Hello, | | I am trying to define a polymorphic state monad using glasgow extensions and I got a | brain explosion of ghc when i try to compile it. | | Here is the code : | | newtype StateT s m a = MkStateT (s -> m (a, s)) | | instance Monad m => Monad (StateT s m) where | return x = MkStateT (\s -> return (x, s)) | MkStateT m1 >>= k = | MkStateT | (\s0 -> do (a, s1) <- m1 s0 | let MkStateT m2 = k a | m2 s1 ) | | data Thread a = forall b . MkThread (StateT (Thread b) [] a) | | instance Monad Thread where | return = MkThread . return | MkThread p >>= k = MkThread ( do x <- p | let MkThread p' = k x | p' ) | | I got this error : | My brain just exploded. | I can't handle pattern bindings for existentially-quantified constructors. | In the binding group | MkThread p' = k x | In the first argument of `MkThread', namely | `(do | x <- p | let MkThread p' = k x | p')' | In the definition of `>>=': | MkThread (do | x <- p | let MkThread p' = k x | p') | | How can i define (>>=) for my thread monad ? | | Thanks in advance for any piece of advice, | Mathieu | | -- | There are only 10 types of people in the world: | Those who understand binary and those who don't. | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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brain explosion in polymorphic state monad
by mathieu 10 Oct '02

10 Oct '02

Hello, I am trying to define a polymorphic state monad using glasgow extensions and I got a brain explosion of ghc when i try to compile it. Here is the code : newtype StateT s m a = MkStateT (s -> m (a, s)) instance Monad m => Monad (StateT s m) where return x = MkStateT (\s -> return (x, s)) MkStateT m1 >>= k = MkStateT (\s0 -> do (a, s1) <- m1 s0 let MkStateT m2 = k a m2 s1 ) data Thread a = forall b . MkThread (StateT (Thread b) [] a) instance Monad Thread where return = MkThread . return MkThread p >>= k = MkThread ( do x <- p let MkThread p' = k x p' ) I got this error : My brain just exploded. I can't handle pattern bindings for existentially-quantified constructors. In the binding group MkThread p' = k x In the first argument of `MkThread', namely `(do x <- p let MkThread p' = k x p')' In the definition of `>>=': MkThread (do x <- p let MkThread p' = k x p') How can i define (>>=) for my thread monad ? Thanks in advance for any piece of advice, Mathieu -- There are only 10 types of people in the world: Those who understand binary and those who don't.

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non-termination during compilation
by Christian Maeder 10 Oct '02

10 Oct '02

Hi, the following example causes ghc to loop (or run rather long): --- snip --- data U = MkU (U -> Bool) russel :: U -> Bool russel u@(MkU p) = not $ p u x :: Bool x = russel (MkU russel) --- snip --- I think, a compiler should always terminate, shouldn't it!? Compilation succeeds for "russel $ MkU russel" instead of "russel (MkU russel)". (Surely, x is bottom and therefore the example is senseless) Regards Christian

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ObjectIO Library
by Alfonso 10 Oct '02

10 Oct '02

Hello: I have the information that The library ObjectIO is included in the ghc.5.0.4 version, unfortunately I download the msi file for windows (ghc-5-04-1.msi) and the library does not appear in the imports directory after the installation. Have I the wrong information? Do I need to download another msi ? How can I use objectIO with version 5.04.1? thank you Alfonso

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