Re: RFC: include a cabal-install executable in future GHC releases
I couldn't find them, and they're not listed at http://www.haskell.org/cabal/download.html (except OS X), or at http://www.haskell.org/haskellwiki/Cabal-Install, or at http://hackage.haskell.org/package/cabal-install. -- Ashley On 2014-05-03 17:00, Carter Schonwald wrote: I think there's now hosted official cabal install binaries online. I'm Afk but they should be a short google away. Should be linked more prominently though On Saturday, May 3, 2014, Ashley Yakeley ash...@semantic.org mailto:ash...@semantic.org wrote: So I want to install GHC + cabal on a new system, building cabal packages with profiling and documentation. Here's what I have to do: 1. Download, unpack and install GHC. 2. Download and unpack cabal-install, and run bootstrap.sh. As part of the bootstrap, it will download and build a bunch of packages. 3. Delete the downloaded packages (rm -rf ~/.ghc/*) because they were built without profiling or documentation. 4. Call cabal update to get a default .cabal/config file. 5. Edit .cabal/config to switch on library-profiling, executable-profiling, and documentation. 6. Build my stuff. This would be much simplified if binary versions of cabal-install were available. (It would be even simpler if they were just included in the GHC builds -- I could eliminate 2 3.) -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Kind Demotion
My workaround is to wrap types of all kinds as kind *: data WrapType (a :: k) ...or better yet, as its own kind: data WrappedType = forall a. WrapType a Now I can make an apples-to-apples comparison of types of different kinds, e.g. WrapType [] and WrapType Bool. All I need now is a way of applying wrapped types: type family WrapApply (f :: WrappedType) (x :: WrappedType) :: WrappedType type instance WrapApply (WrapType (f :: ka - kfa)) (WrapType (a :: ka)) = WrapType (f a) -- Ashley Yakeley On 17/09/12 06:05, Richard Eisenberg wrote: I see what you're getting at, but the problem is more fundamental than just the lack of a type *. GHC has no notion of equality between kinds other than syntactic identity. If two kinds are other than syntactically identical, they are considered distinct. This fact basically renders your approach doomed to failure. Furthermore, a promoted datatype and the unpromoted datatype are distinct entities with the same names, so you can't just use a variable both at the kind level and the type level (variable ka in your final ConstructedT example). It is not hard to write a Demote type family that computes an unpromoted datatype from its promoted kind, but that type family will interfere with type inference. That's all the bad news. The good news is that some of us are working out how to extend GHC's rich notion of type equality to the kind level, which would also allow intermingling of type- and kind-variables. We're still a little ways out from starting to think about implementing these ideas, but there's a good chance that what you want will be possible in the (not-so-terribly-long-term) future. Richard On Sep 17, 2012, at 12:41 AM, Ashley Yakeley wrote: TypeRep does indeed resemble * as a type. I'm working on a system for reification of types, building on my open-witness package (which is essentially a cleaner, more Haskell-ish alternative to TypeRep). Firstly, there's a witness type to equality of types: data EqualType :: k - k - * where MkEqualType :: EqualType a a Then there's a class for matching witnesses to types: class SimpleWitness (w :: k - *) where matchWitness :: w a - w b - Maybe (EqualType a b) Then I have a type IOWitness that witnesses to types. Through a little Template Haskell magic, one can declare unique values of IOWitness at top level, or just create them in the IO monad. Internally, it's just a wrapper around Integer, but if the integers match, then it must have come from the same creation, which means the types are the same. data IOWitness (a :: k) = ... instance SimpleWitness IOWitness where ... OK. So what I want to do is create a type that's an instance of SimpleWitness that represents types constructed from other types. For instance, [Integer] is constructed from [] and Integer. data T :: k - * where DeclaredT :: forall ka (a :: ka). IOWitness a - T a ConstructedT :: forall kfa ka (f :: ka - kfa) (a :: ka). T f - T a - T (f a) instance SimpleWitness T where matchWitness (DeclaredT io1) (DeclaredT io2) = matchWitness io1 io2 matchWitness (ConstructedT f1 a1) (ConstructedT f2 a2) = do MkEqualType - matchWitness f1 f2 MkEqualType - matchWitness a1 a2 return MkEqualType matchWitness _ _ = Nothing But this doesn't work. This is because when trying to determine whether f1 a1 ~ f2 a1, even though f1 a1 has the same kind as f2 a2, that doesn't mean that a1 and a2 have the same kind. To solve this, I need to include in ConstructedT a witness to ka, the kind of a: ConstructedT :: forall kfa ka (f :: ka - kfa) (a :: ka). IOWitness ka - T f - T a - T (f a) matchWitness (ConstructedT k1 f1 a1) (ConstructedT k2 f2 a2) = do MkEqualType - matchWitness k1 k2 MkEqualType - matchWitness f1 f2 MkEqualType - matchWitness a1 a2 return MkEqualType Sadly, this doesn't work, for two reasons. Firstly, there isn't a type for *, etc. Secondly, GHC isn't smart enough to unify two kinds even though you've given it an explicit witness to their equality. -- Ashley Yakeley On 16/09/12 20:12, Richard Eisenberg wrote: If you squint at it the right way, TypeRep looks like such a type *. I believe José Pedro Magalhães is working on a revision to the definition of TypeRep incorporating kind polymorphism, etc., but the current TypeRep might work for you. Your idea intersects various others I've been thinking about/working on. What's the context/application? Thanks, Richard On Sep 16, 2012, at 7:09 PM, Ashley Yakeley wrote: Now that we have type promotion, where certain types can become kinds, I find myself wanting kind demotion, where kinds are also types. So for instance there would be a '*' type, and all types of kind * would be demoted to values of it. Is that feasible? -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http
Kind Demotion
Now that we have type promotion, where certain types can become kinds, I find myself wanting kind demotion, where kinds are also types. So for instance there would be a '*' type, and all types of kind * would be demoted to values of it. Is that feasible? -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Kind Demotion
TypeRep does indeed resemble * as a type. I'm working on a system for reification of types, building on my open-witness package (which is essentially a cleaner, more Haskell-ish alternative to TypeRep). Firstly, there's a witness type to equality of types: data EqualType :: k - k - * where MkEqualType :: EqualType a a Then there's a class for matching witnesses to types: class SimpleWitness (w :: k - *) where matchWitness :: w a - w b - Maybe (EqualType a b) Then I have a type IOWitness that witnesses to types. Through a little Template Haskell magic, one can declare unique values of IOWitness at top level, or just create them in the IO monad. Internally, it's just a wrapper around Integer, but if the integers match, then it must have come from the same creation, which means the types are the same. data IOWitness (a :: k) = ... instance SimpleWitness IOWitness where ... OK. So what I want to do is create a type that's an instance of SimpleWitness that represents types constructed from other types. For instance, [Integer] is constructed from [] and Integer. data T :: k - * where DeclaredT :: forall ka (a :: ka). IOWitness a - T a ConstructedT :: forall kfa ka (f :: ka - kfa) (a :: ka). T f - T a - T (f a) instance SimpleWitness T where matchWitness (DeclaredT io1) (DeclaredT io2) = matchWitness io1 io2 matchWitness (ConstructedT f1 a1) (ConstructedT f2 a2) = do MkEqualType - matchWitness f1 f2 MkEqualType - matchWitness a1 a2 return MkEqualType matchWitness _ _ = Nothing But this doesn't work. This is because when trying to determine whether f1 a1 ~ f2 a1, even though f1 a1 has the same kind as f2 a2, that doesn't mean that a1 and a2 have the same kind. To solve this, I need to include in ConstructedT a witness to ka, the kind of a: ConstructedT :: forall kfa ka (f :: ka - kfa) (a :: ka). IOWitness ka - T f - T a - T (f a) matchWitness (ConstructedT k1 f1 a1) (ConstructedT k2 f2 a2) = do MkEqualType - matchWitness k1 k2 MkEqualType - matchWitness f1 f2 MkEqualType - matchWitness a1 a2 return MkEqualType Sadly, this doesn't work, for two reasons. Firstly, there isn't a type for *, etc. Secondly, GHC isn't smart enough to unify two kinds even though you've given it an explicit witness to their equality. -- Ashley Yakeley On 16/09/12 20:12, Richard Eisenberg wrote: If you squint at it the right way, TypeRep looks like such a type *. I believe José Pedro Magalhães is working on a revision to the definition of TypeRep incorporating kind polymorphism, etc., but the current TypeRep might work for you. Your idea intersects various others I've been thinking about/working on. What's the context/application? Thanks, Richard On Sep 16, 2012, at 7:09 PM, Ashley Yakeley wrote: Now that we have type promotion, where certain types can become kinds, I find myself wanting kind demotion, where kinds are also types. So for instance there would be a '*' type, and all types of kind * would be demoted to values of it. Is that feasible? -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: [Haskell] Re: ANNOUNCE: GHC version 6.10.2
Duncan Coutts wrote: In the mean time you can just: $ cabal install time Where do I get the cabal command? I'm installing GHC on a new machine and I was hoping it would be included. I can't obtain it via cabal install cabal-install because I don't have the cabal command and I don't know how to tie the knot in this case. -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Breakage with ghc-6.10
On Fri, 2008-10-10 at 09:08 -0700, Duncan Coutts wrote:
Data/Time/Clock/CTimeval.hs:1:11:
Warning: -ffi is deprecated: use -XForeignFunctionInterface or
pragma {-# LANGUAGE ForeignFunctionInterface#-} instead
no location info:
Failing due to -Werror.
Nooo!!
This is the reason that hackage now rejects the use of -Werror in
released packages. It causes unnecessary breakage when new compilers
add new warnings.
Warnings in a build process should be fixed, not ignored (and, I would
say, fixed by whoever introduced the warning or otherwise broke the
build).
Hackage, on the other hand, is right to reject -Werror in .cabal files,
as there the build is really part of the install process and should be
as lenient as possible. I pass --ghc-options=-Wall -Werror to cabal in
a Makefile in most of my projects, so that my development build process
is strict.
--
Ashley Yakeley
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importing in place and packages
I'm compiling the files for package javavm with GHC 6.6 (using -package-name javavm). As part of the compilation process, I need a runnable program that uses the modules I've compiled in place: import JVMBoot But I get this error when compiling my Main module (ShowClasses.hs): ShowClasses.hs:23:1: Bad interface file: JVMBoot.hi Something is amiss; requested module main:JVMBoot differs from name found in the interface file javavm:JVMBoot Really I want to import javavm:JVMBoot, not main:JVMBoot. I tried this, but GHC doesn't like it (because it's not Haskell): import javavm:JVMBoot I tried compiling ShowClasses.hs with -package-name javavm. This let me compile, but then I get this on link: /usr/bin/ld: Undefined symbols: _ZCMain_main_closure ___stginit_ZCMain collect2: ld returned 1 exit status I tried adding a -main-is in the compile step, but this didn't help. Is there any way to create a main function that calls files imported in place that are in some package? I have the same issue when writing tests for my time package. -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: importing in place and packages
Simon Peyton-Jones wrote: Anyway, the solution for you is to install it. I can't install it, the package isn't finished being built at that point. Or perhaps I could find a way of installing the partial package to the user database. I build part of package javavm. Then I use that to build ShowClasses. Then I run ShowClasses to generate more source files. Then I use those to build the rest of javavm. -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Major type-class overhaul
Simon Peyton-Jones wrote: 3. Dictionaries are packaged in data constructors This feature has been often requested, becuase it allows you to package a dictionary into an ordinary (non-existential) data type, and be able to use it. Indeed, one can now simply reify class instances: data NumInst a where MkNumInst :: Num a = NumInst a intInst :: NumInst Int intInst = MkNumInst plus :: NumInst a - a - a - a plus MkNumInst p q = p + q Expect a whole new batch of type shenanigans from Oleg. -- Ashley Yakeley Seattle, WA ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Missing Folder in ghc?
Simon Marlow wrote: It looks like you expected to build GHC by grabbing the darcs repo and reading the README file - that isn't a route I anticipated :-) I'll make sure the README gets updated at some point. Thanks. Now the build process gets stuck here: ==fptools== make all -wr -f Makefile; in /home/ashley/Projects/Collected/Haskell/ghc/libraries/base rm -f GHC/Base.o; if [ ! -d GHC/Base_split ]; then mkdir GHC/Base_split; else /usr/bin/find GHC/Base_split -name '*.o' -print | xargs rm -f __rm_food; fi; ../../ghc/compiler/ghc-inplace -H16m -O -fglasgow-exts -cpp -Iinclude -#include HsBase.h -funbox-strict-fields -ignore-package base -O -Rghc-timing -fgenerics -fgenerics -split-objs-c GHC/Base.lhs -o GHC/Base.o -ohi GHC/Base.hi The compiler just sits and does nothing for hours. It doesn't even use any CPU, it seems to be just waiting for something (in state S+ according to ps). I tried running the command with -H64m, but that didn't help. With -v it gives this: Glasgow Haskell Compiler, Version 6.5, for Haskell 98, compiled by GHC version 6.4 Using package config file: /home/ashley/Projects/Collected/Haskell/ghc/ghc/driver/package.conf.inplace Using package config file: /home/ashley/.ghc/i386-linux-6.5/package.conf package haskell98-1.0 will be ignored due to missing dependencies: base-1.0 package template-haskell-1.0 will be ignored due to missing dependencies: base-1.0 package unix-1.0 will be ignored due to missing dependencies: base-1.0 package Cabal-1.1.4 will be ignored due to missing dependencies: base-1.0 package parsec-2.0 will be ignored due to missing dependencies: base-1.0 package haskell-src-1.0 will be ignored due to missing dependencies: base-1.0 package network-1.0 will be ignored due to missing dependencies: base-1.0 package QuickCheck-1.0 will be ignored due to missing dependencies: base-1.0 package HUnit-1.1 will be ignored due to missing dependencies: base-1.0 package mtl-1.0 will be ignored due to missing dependencies: base-1.0 package fgl-5.2 will be ignored due to missing dependencies: base-1.0 package stm-1.0 will be ignored due to missing dependencies: base-1.0 package readline-1.0 will be ignored due to missing dependencies: base-1.0 Hsc static flags: -static *** Literate pre-processor: /home/ashley/Projects/Collected/Haskell/ghc/ghc/utils/unlit/unlit -h GHC/Base.lhs GHC/Base.lhs /tmp/ghc28900_0.lpp *** C pre-processor: gcc -E -undef -traditional -v -I include -I /home/ashley/Projects/Collected/Haskell/ghc/ghc/includes -D__HASKELL1__=5 -D__GLASGOW_HASKELL__=605 -D__HASKELL98__ -D__CONCURRENT_HASKELL__ -Dlinux_BUILD_OS=1 -Di386_BUILD_ARCH=1 -Dlinux_HOST_OS=1 -Di386_HOST_ARCH=1 -x c /tmp/ghc28900_0.lpp -o /tmp/ghc28900_0.hscpp Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --with-gxx-include-dir=/usr/include/c++/4.0.2 --enable-shared --with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu9) /usr/lib/gcc/i486-linux-gnu/4.0.2/cc1 -E -traditional-cpp -quiet -v -I include -I /home/ashley/Projects/Collected/Haskell/ghc/ghc/includes -D__HASKELL1__=5 -D__GLASGOW_HASKELL__=605 -D__HASKELL98__ -D__CONCURRENT_HASKELL__ -Dlinux_BUILD_OS=1 -Di386_BUILD_ARCH=1 -Dlinux_HOST_OS=1 -Di386_HOST_ARCH=1 /tmp/ghc28900_0.lpp -o /tmp/ghc28900_0.hscpp -mtune=i486 -undef ignoring nonexistent directory /usr/local/include/i486-linux-gnu ignoring nonexistent directory /usr/include/i486-linux-gnu #include ... search starts here: #include ... search starts here: include /home/ashley/Projects/Collected/Haskell/ghc/ghc/includes /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.0.2/include /usr/include End of search list. *** Checking old interface for GHC.Base: *** Parser: *** Renamer/typechecker: *** Desugar: Result size = 2851 *** Simplify: It stops and waits there. This is my machine: $ uname -a Linux rollright 2.6.12-10-386 #1 Mon Feb 13 12:13:15 UTC 2006 i686 GNU/Linux ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Missing Folder in ghc?
Simon Marlow wrote: The configure script has mis-detected your GHC version somehow. Could you look through the output of configure, and see what it says about GHC? Nothing special: checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking target system type... i686-pc-linux-gnu Canonicalised to: i386-unknown-linux checking for path to top of build tree... /home/ashley/Projects/Collected/Haskell/ghc checking for ghc... /usr/bin/ghc checking version of ghc... 6.4 checking for nhc... no checking for nhc98... no checking for hbc... no Also look in mk/config.mk, at the value of GhcCanonVersion. GHC = /usr/bin/ghc GhcDir = $(dir $(GHC)) GhcVersion = 6.4 GhcMajVersion = 6 GhcMinVersion = 4 GhcPatchLevel = 0 # Canonicalised ghc version number, used for easy (integer) version # comparisons. We must expand $(GhcMinVersion) to two digits by # adding a leading zero if necessary: ifneq $(findstring $(GhcMinVersion), 0 1 2 3 4 5 6 7 8 9) GhcCanonVersion = $(GhcMajVersion)0$(GhcMinVersion) else GhcCanonVersion = $(GhcMajVersion)$(GhcMinVersion) endif Maybe you switched GHC versions but didn't reconfigure? I think the problem is that I called autoconf etc. before I called darcs-all get, but not after. Calling autoreconf fixed the problem. -- Ashley Yakeley ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Missing Folder in ghc?
Lemmih wrote: Did you run 'sh darcs-all get'? Oh, that wasn't in the README. Thanks. But now I get this: /usr/bin/ghc -H16m -O -I. -Iinclude -Rghc-timing -I../../../libraries -fglasgow-exts -no-recomp-c System/Directory/Internals.hs -o System/Directory/Internals.o -ohi System/Directory/Internals.hi System/Directory/Internals.hs:1:0: Module `System.Directory.Internals' is a member of package base-1.0. To compile this module, please use -ignore-package base-1.0. I'm using GHC 6.4. ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Duplicate instance declarations
Bulat Ziganshin wrote: Hello all why the folowing is not allowed even with all extensions enabled both in Hugs and GHC? class BufStream h where class CharStream h where instance (CharStream h) = BufStream h where class MemoryStream h where instance (MemoryStream h) = BufStream h where Try this: class (BufStream h) = CharStream h where class (BufStream h) = MemoryStream h where ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: Visual Haskell version 0.0
In article [EMAIL PROTECTED] ft.com, Simon Marlow [EMAIL PROTECTED] wrote: A quick note about the license: this is a binary release with a BSD license. We changed the license at the last minute, and didn't have time to re-roll the installer. You have the option of using Visual Haskell either under the click-through license in the installer (a Microsoft shared source license for non-commercial use) or the more liberal BSD license in the documentation. Will you be coming out with another installer? I'm not comfortable clicking accept on the MSR license... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: GHC version 6.4
Simon Marlow [EMAIL PROTECTED] wrote: = The (Interactive) Glasgow Haskell Compiler -- version 6.4 = The GHC Team is delighted to announce a new major release of GHC. Some issues: 1. ghc -M complains about multiply-defined Main modules. entered as http://sourceforge.net/tracker/index.php?func=detailaid=1162736group_i d=8032atid=108032 2. What's up with Warning: orphan instances? 3. I notice show for rationals now does 3%2 instead of 3 % 2. Probably better, though it does break one of my tests... 4. It looks like Data.FiniteMap has been renamed Data.Map, or something. There's no Data.Map at http://haskell.org/haddock/libraries/, do these need to be updated? 5. Apparently a bunch of stuff is in different pacakges, such as mtl. Is there documentation about what's in what package? Perhaps Haddock should show packages or something? I'm not yet familiar enough with Cabal to know what the best way of doing this is. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
recursive group context bug?
I suspect someone's come across this before, so maybe there's an
explanation for it.
This does not compile:
module Bug where
{
p :: IO ();
p = q = id;
q :: (Monad m) = m (IO ());
q = return p;
}
Bug.hs:3:
Mismatched contexts
When matching the contexts of the signatures for
p :: IO ()
q :: forall m. (Monad m) = m (IO ())
The signature contexts in a mutually recursive group should all be
identical
When generalising the type(s) for p, q
The code looks correct to me. Why must the signature contexts be
identical in this case?
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Re: Using Haskell with Java
In article [EMAIL PROTECTED], Dmitri Pissarenko [EMAIL PROTECTED] wrote: Can Haskell and Java parts of a system co-operate? See my JVM-Bridge, https://sourceforge.net/projects/jvm-bridge/ -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: F#
In article [EMAIL PROTECTED], Manuel M T Chakravarty [EMAIL PROTECTED] wrote: Generally, phrases such as XYZ is excellent within certain niches sounds like cheap propaganda to me. If you replace Haskell by Linux, I am sure you'll find similar statements on other Microsoft web pages ;-) Doubtless. I think if they're casting about for excuses not to use Haskell, they're unlucky not to have hit on time/space issues. Anyway, I've rewritten it for them: Purely functional languages like Haskell are excellent to write in, but non-trivial work is involved with implementing a lazy language in a strict run-time environment. ... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: F#
In article [EMAIL PROTECTED], Manuel M T Chakravarty [EMAIL PROTECTED] wrote: On Fri, 2004-05-21 at 10:07, John Sharley wrote: I note this remark on the Microsoft Research site (http://research.microsoft.com/projects/ilx/fsharp.aspx) quote Purely functional languages like Haskell are excellent within certain niches, but unfortunately some simple programming exercises can quickly turn into problems that require a PhD. to solve. /quote Are the Microsoft Research people working on GHC or anyone else on this list also of this opinion? If so, why? This is a clear case of FUD: http://en.wikipedia.org/wiki/FUD I agree. It's been changed now, however: Purely functional languages like Haskell are excellent within certain niches, but non-trivial problems exist with language interoperability between lazy and strict languages. Given your work on FFI, would you care to comment? I wonder if F# really is as obviously preferable to a Haskell# as they claim? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Happy Question
My hand-written S-expression parser for HScheme is very very slow. Really quite a bit slower than it ought to be. So I'd like to switch to Happy instead. The problem is my parser should be monadic, but the monad type is generalised (basically of the form (context m) = m). Is there a way of switching on monadic-ness, so I can have a monadic happyError, but without giving type signatures to happyThen and happyReturn? Or else allowing a class context for the type signatures? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
GHC Warning Request
When -fwarn-unused-imports is switched on, import M() should not issue a warning. In 6.2, it does. The idea is that I only wish to import instance declarations here, and that's the obvious way of making that explicit. I'm using -Werror (new in 6.2, thanks), and most of the time I'm interested in knowing about superfluous imports. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: GHC version 6.0.1
In article [EMAIL PROTECTED], Ian Lynagh [EMAIL PROTECTED] wrote: Debian packages are now in the archive for unstable; just apt-get update and apt-get install ghc6 ghc6-prof ghc6-doc. There are also ghc6-hopengl, ghc6-threaded-rts and ghc6-libsrc packages. It should enter testing in 10 days time. /usr/bin/ghc etc. links don't work out of the box. It looks like your post-install script needs to call update-alternatives on the four links. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ways and Build Tags for Optimisation
In article [EMAIL PROTECTED] ft.com, Simon Marlow [EMAIL PROTECTED] wrote: -rw-r--r--1 ashley ashley2117554 May 28 04:04 HBase.hi -rw-r--r--1 ashley ashley2119865 May 28 08:15 HBase.p hi -rw-r--r--1 ashley ashley 72669 May 28 16:20 HBase.q hi Wow :-) It looks like the problem is very data-heavy Unicode property files. For instance, Org.Org.Semantic.HBase.Text.UnicodeNames exports just one value: getCharacterName :: Char - String Inside the module is an Array Char String created from a [(Char,String)] that is a long list of Unicode character names. The file is automatically generated from a downloaded data file. For instance: getCharacterName '\x189F' MONGOLIAN LETTER MANCHU ALI GALI DDHA For some reason, even though only getCharacterName is exported, when optimisation is switched on, the interface file balloons a thousandfold: $ ls -l UnicodeNames.*hi -rw-r--r--1 ashley ashley5854480 May 28 02:49 UnicodeNames.hi -rw-r--r--1 ashley ashley5854497 May 28 06:56 UnicodeNames.p_hi -rw-r--r--1 ashley ashley 2385 May 28 15:59 UnicodeNames.q_hi What's the best way to stop this? Is it reasonable to simply switch off profiling just for these few files? Also, I'd like to make all that data disappear when a binary program that doesn't use it is stripped; currently it doesn't. Any ideas? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Ways and Build Tags for Optimisation
I'd like to include three different flavours of my HBase package, with these combinations of optimisation and profiling: release: optimised (with -O -fvia-C) profiling: optimised and profiled quick: neither The release and profiling flavours take forever to compile, so it's useful to have a quick flavour to speed up the development cycle. The trouble is, any Haskell program using the release flavour of HBase also compiles very slowly, even if it itself does not use -O. If nothing else, this may be due to the huge interface file for the root import: $ ls -Al HBase.*hi -rw-r--r--1 ashley ashley2117554 May 28 04:04 HBase.hi -rw-r--r--1 ashley ashley2119865 May 28 08:15 HBase.p_hi -rw-r--r--1 ashley ashley 72669 May 28 16:20 HBase.q_hi So what I'd like to do is include the quick version with suffices .q_hi and .q_o within the hbase package, just as profiling has .p_hi and .p_o. However, simply using -hisuf and -osuf seems not to be sufficient to force GHC to use those suffices when looking for files within HBase. I looked in fptools/ghc/compiler/main/DriverState.hs to see how GHC does this sort of thing for profiling: the file speaks of ways and build tags but I can't find any reference to these in the GHC manual. How would I use one of the user ways? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: GHC vesrion 5.04.3 released
In article [EMAIL PROTECTED],
Wolfgang Thaller [EMAIL PROTECTED] wrote:
A Mac OS X installer package is now available at
http://www.uni-graz.at/imawww/haskell/GHC.5.04.3.dmg
It includes profiling libraries (this time, they should work), but not
the documentation (use the online docs instead).
This binary requires Mac OS X 10.2 (Jaguar). It will not work on Mac OS
X 10.1.
Profiling libraries are still buggy. This file fails to link with
profiling set:
module Main where
{
import System.IO;
main :: IO ();
main = putStrLn (show ReadMode);
}
$ ghc -prof ProfTest.hs -o ProfTest_p
ld: warning table of contents of library:
/usr/local/lib/ghc-5.04.3/libHSbase_p.a not sorted slower link editing
will result (use the ranlib(1) -s option)
ld: Undefined symbols:
_GHCziHandle_ReadMode_static_info
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 5.04.3
$ uname -a
Darwin Avebury.local. 6.4 Darwin Kernel Version 6.4: Wed Jan 29 18:50:42
PST 2003; root:xnu/xnu-344.26.obj~1/RELEASE_PPC Power Macintosh powerpc
$
--
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Type Inference Infelicity
This should compile, shouldn't it?
-- ghc -c -fglasgow-exts TestInfer.hs
module TestInfer where
{
class C t a b | t a - b;
instance C Char a Bool;
data P t a = forall b. (C t a b) = MkP b;
data Q t = MkQ (forall a. P t a);
f' :: Q Char;
f' = MkQ (MkP True :: forall a. P Char a);
f :: Q Char;
f = MkQ (MkP True);
}
GHC 5.04.2 for MacOS X complains about f, but not about f':
TestInfer.hs:15:
Could not deduce (C t a Bool) from the context ()
Probable fix:
Add (C t a Bool) to the When generalising the type of an
expression
Or add an instance declaration for (C t a Bool)
arising from use of `MkP' at TestInfer.hs:15
In the first argument of `MkQ', namely `(MkP True)'
In the definition of `f': MkQ (MkP True)
--
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ghcfilt
Is there a ghcfilt equivalent of c++filt that will unmangle 'z'-escaped GHC symbols? Is the mangling written up somewhere? I might be able to write something... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Bug in GHC 5.04.2 for Mac OS X
At 2003-01-30 20:27, I wrote: GPR13 is indeed considered nonvolatile, so it looks like the JVM is correct and the function made by createAdjustor is wrong. See enclosed example. -- Ashley Yakeley, Seattle WA GPR13Bug.tar.gz Description: Binary data
Re: Native Threads in the RTS
At 2002-11-26 09:37, Alastair Reid wrote: 1) forkNativeThread :: IO () - IO () The fresh Haskell thread is bound to a fresh native thread. 2) forkIO :: IO () - IO () The fresh Haskell thread is not bound to a native thread. Are you sure you intend to change the type of forkIO? Currently it's forkIO :: IO () - IO ThreadId -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: -Werror Request
At 2002-11-20 01:38, Simon Peyton-Jones wrote: Done! Thanks! -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
-Werror Request
If it's not too much work, I'd like to request a -Werror option for GHC that would turn warnings into errors. Sometimes warnings one would like to catch get lost in a long make process. Thanks... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Database library?
At 2002-10-16 09:49, Bryn Keller wrote: Does anyone have a GHC-friendly library for accessing databases, specifically Oracle and MSSQL? My HBase project includes HMySQL, for accessing MySQL databases. It's kind of a separate project from HBase (because it uses FFI), but it's in the same CVS repository. It's rather incomplete at the moment. http://sourceforge.net/projects/hbase/ HBase proper includes an interesting monad for generating SQL SELECT statements. But HBase is it's own little world, replacing the Prelude... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Rts.h and C++ Annoyance
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 ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Building Both Regular and Profiling Libraries
At 2002-10-10 01:23, Ketil Z. Malde wrote: Ashley Yakeley [EMAIL PROTECTED] writes: I did notice that for -osuf you seem to need the '.' but for -hisuf you don't... Weird, I've never seen that behavior (GHC 5.02 and 5.04, x86-Linux and Sparc-Solaris). I just checked with 5.04 on my Linux box, and 5.02 on a Sun, just to make sure. What system and compiler version are you using? My mistake, I'm using -o, which overrides -osuf... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Building Both Regular and Profiling Libraries
Is there a good strategy for building both regular and profiling variants of libraries? One of the problems is that the .hi files are not compatible, so I need to both kinds of those too. Should I be giving them separate names or something? How do people deal with this? Right now I do a 'make clean' and then rebuild with profiling options, but that's kind of annoying... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Building Both Regular and Profiling Libraries
At 2002-10-09 04:21, Simon Peyton-Jones wrote: Yes there is. In your build.mk, set GhcLibWays = p This is discussed a lot in the Building Guide, which I commend to you if you are building GHC. I'm not building GHC. I just want to build my own stuff and I don't have a build.mk... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Building Both Regular and Profiling Libraries
At 2002-10-09 07:48, Hal Daume III wrote: Is this the sort of thing you're looking for? Yes, thanks. I now have these in my Makefile: HCPOPTS = -prof -hisuf p_hi -osuf .p_o -auto-all +RTS -K32M -RTS depend-entries: $(HC_SRCS) $(HC) -M -optdep-s -optdepp $(HCFLAGS) $^ I did notice that for -osuf you seem to need the '.' but for -hisuf you don't... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: -package-name
At 2002-10-08 03:04, Simon Peyton-Jones wrote: Definitely not. Definitely not worthwhile? Should I be using -package-name foo when compiling for my package foo? Packages are the unit of distribution, and the unit of library archive, in GHC. If you import a module Foo, GHC has to figure out which libBaz.a to link. I assumed that GHC linked to all libraries mentioned in all those packages specified with -package. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: -package-name
At 2002-10-08 04:26, Simon Peyton-Jones wrote: Ah, it's the -package flag we are planning to get rid of! Aha. So how will GHC find all the various module imports? I'd rather be using -package foo than -i/usr/local/share/foo/haskell/imports. Or is there going to be some standard, official place for everyone's .hi files to be installed in, such as the GHC imports directory? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
-package-name
Is the -package-name mechanism still worthwhile now that we have hierarchical modules? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: replacing the Prelude (again)
At 2002-07-15 01:05, Simon Peyton-Jones wrote: I quite like the fact that you would then have to say import MyPrelude as Prelude thereby stressing that you are importing the Prelude stuff. Doesn't this assume your Prelude stuff is all in one module? Or can you import several modules as Prelude? As a Prelude-replacer, my preference is rather towards keeping it as it is... it seems a bit simpler and easier to understand. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: GHC version 5.04 released
At 2002-07-11 11:22, Eray Ozkural wrote: A Windows installer for 5.04 is now available via the GHC downloads page: http://haskell.org/ghc/download_ghc_504.html /me pings debian people. we can't lag behind windows, come on ;) I'm sure Michael Weber is working on it even as we speak... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Dynamic Libraries on MacOS X
At 2002-06-10 04:03, Simon Marlow wrote: It sounds like frameworks are similar in concept to GHC's packages. They solve a similar problem in a quite different way. A framework is a bundle: an actual directory with everything inside it, libraries, header files, localised strings, whatever, with a particular internal structure that does clever stuff with symbolic links to handle multiple versions. Frameworks and other bundles (such as applications) may be relocated by the user, though frameworks generally need to be in certain standard places so that other tools can find them. Bundles may be uninstalled simply by deleting the directory. Generally the Mac GUI shows the directory as an object rather than a folder, though there's a special menu option to open the directory up like any folder. By contrast, GHC packages are virtual i.e. the stuff is not necessarily all in one directory. And if any of it gets moved, the package.conf file would need to be updated. For code-generating tools, you point to frameworks on the command-line much as you do libraries. For instance, just as you do -lfoo -L./foolibs to refer to libfoo and to search for libraries in ./foolibs/, you'd do -framework foo -F ./foofws to refer to foo.framework and to search in ./foofws/ for frameworks (there are also standard places to search). The Darwin C compiler can use this to find include files, and then you can pass the same options to the linker, and it will find the libraries. Too bad frameworks aren't standard on all UNIX, they are an excellent way of packaging software. *) add two command line options that get passed on to the linker (-framework for linking with a framework and -F for specifying framework search paths) *) add corresponding entries to package.conf You mean add a new package for each framework? I think Wolfgang means add new package specification components, such as frameworks and frameworks_dir. They just need to be passed on to the linker. One interesting possibility would be to allow support for .hi files in frameworks. This would mean GHC would look inside frameworks specified by the -framework flag and frameworks package.conf entries for .hi files, in addition to -I and import_dirs. This would mean a bit more code but I believe Apple provides APIs for dealing with bundles easily. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
GHC Ownership
At 2002-06-11 08:18, Simon Marlow wrote: This is *so* annoying when all we're trying to do is write free software here. This reminds me... who legally owns GHC? * the University of Glasgow? * Simon and Simon? * Microsoft? * many different people and institutions? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Replacing the Prelude
Ping!
At 2002-05-14 07:17, Simon Peyton-Jones wrote:
Ashley writes
| I was hoping to do something similar for 'do' notation by redefining
| (), (=) etc., but unfortunately GHC is quite insistent
| that 'do' notation quite specifically refers to GHC.Base.Monad
Dylan replies
| I'm surprised that ghc uses the fromInteger and fromRational
| that are in scope; I thought there was general agreement that
| it should use the Prelude.from{Integer,Rational} in scope.
Ashley is referring to a GHC extension. Normally, GHC uses
Prelude.fromInteger etc, regardless of what is in scope. But if you
say -fno-implicit-prelude, GHC will instead use whatver fromInteger
is in scope. (This is documented in the manual.)
Ashley's question, as I understand is whether something similar
could be done for monads.
Answer: I think so, without much bother. I'm beavering away on
a Haskell workshop paper at the moment, but ping me in a fortnight
to do it.
Simon
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Overlapping Instance Thoughts
At 2002-05-21 07:25, Simon Peyton-Jones wrote: Overlapping instances are a terrific swamp and while they are interesting I don't think I'm going to spend a lot of time on them in the near future, I'm afraid. But perhaps someone else can.. I would say the overlapping instances issue is one of the more important ones in the extended language. I'm sure most Haskell programmers have been tripped up by it at least once or twice. It's certainly the thing I most frequently bang my head against. There are in fact some different issues here. 1. There are instances that don't actually overlap, but only because of class contexts: class C a; class D a; instance C Bool; instance (D a) = C a; GHC rejects this, because it only looks at the instance heads, not the contexts. Ideally GHC would accept this as non-overlapping, but then prohibit instances of different classes that caused the two instances to overlap, such as this: instance D Bool; 2. There's also times when the programmer would like instances that really do overlap. Now GHC already has a -fallow-overlapping-instances flag to allow overlaps where one is a strict subset of the other: the more special case takes priority over the more general. But sometimes this isn't enough. For instance, while writing a Scheme interpreter, I wanted to do something like this: newtype Constant a = MkConstant a; -- members omitted class (Monad m) = MonadGettableReference m r where ... instance (Monad m) = MonadGettableReference m Constant where ... instance (MonadGettableReference m r) = MonadGettableReference (SchemeCPS r (m p)) r where ... Unfortunately the two instances overlap, here: MonadGettableReference (SchemeCPS Constant (m p)) Constant In fact it wouldn't actually matter which instance was used in this case, and I suspect that's typical of good class design. So perhaps an -fallow-incoherent-instances flag that just arbitrarily picked one might be helpful. Better would be some mechanism for allowing the programmer to specify which instances defer to which. Or else extend -fallow-overlapping-instances to allow disambiguating instances: class C a b; instance C a (); instance C () a; instance C () (); Here, the third instance is precisely the overlap of the other two. But apparently this too has problems: I don't understand all the implications of this. For example, what if we have an instance that doesn't match C () () now, but may do 'later' when a type variable has been instantiated. I don't doubt Simon PJ when he says this is a terrific swamp. I think any work anyone might wish to do cutting through the swamp that ended up in the language would be very valuable. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: -fallow-overlapping-instances Request
At 2002-05-17 03:54, Johannes Waldmann wrote: From a type-theoretic viewpoint, instance declarations are relations between (sets of) trees (= elements of the respective data types). So one needs representations of such relations with effective decidability of overlapping-ness, most-sepcific-ness and such. Yeah but unfortunately GHC doesn't look at the contexts of instance declarations. It has a straightforward but rather conservative concept of overlapping and most specific. I'd like to see that fixed too, but that's a separate issue. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
-fallow-overlapping-instances Request
Currently -fallow-overlapping-instances only allows overlapping instances if one is a strict subset of the other. This is good (determinate), but sometimes you really need two instances that partially overlap. It would be nice if this could be disambiguated simply with another instance declaration. For instance: class C a b; instance C a (); instance C () a; instance C () (); As you can see, the first two instances partially overlap, but the third one disambiguates. I think it would be nice if GHC -fallow-overlapping-instances allowed this. This would take some of the pain out of overlapping instance resolution... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Exceptions and IO
My confusion surrounding exceptions in the IO monad comes from the fact
that IO failures and bottom are not cleanly separated. I had always
assumed the IO monad looked something like this:
newtype IO a = IO (RealWorldState - Either IOFailure
(RealWorldState,a))
return a = IO (\r - Right (r,a))
fail s = IO (\r - Left (userFailure s))
This would make sense, I think, because it's so easy this way for
Prelude.catch to catch all IOFailures but leave pure bottom exceptions
alone, just as the report says. But in fact IO looks more like this:
newtype IO a = IO (RealWorldState - (RealWorldState,a))
return a = IO (\r - (r,a))
fail s = IO (\r - throw (userError s))
...which means Prelude.catch has to separate out exceptions caused by
fail from those caused by error, etc. and there's confusion between
bottom and exceptions that happen entirely in IO.
--
Ashley Yakeley, Seattle WA
-- ghc -package lang TestException.hs -o TestException ./TestException
module Main where
{
import IORef;
import qualified Exception;
getPureException :: a - IO (Maybe Exception.Exception);
getPureException a = (Exception.catch (seq a (return Nothing)) (return .
Just));
showIOS :: String - IO String - IO ();
showIOS s ios = do
{
putStr (s ++ : );
mpe - getPureException ios;
case mpe of
{
Just pe - putStrLn (pure exception (++ (show pe) ++));
Nothing - Exception.catch (Prelude.catch (do
{
result - ios;
mrpe - getPureException result;
case mrpe of
{
Just pe - putStrLn (returned pure exception
(++ (show pe) ++));
Nothing - putStrLn (value (++ (show result)
++));
};
}) (\e - putStrLn (IO failure ( ++ (show e) ++)))
)
(\e - putStrLn (IO other exception ( ++ (show e)
++)));
};
};
evaluate' :: a - IO a;
evaluate' a = a `seq` return a;
evaluate'' :: a - IO a;
evaluate'' a = (Exception.catch (seq a (return a)) (\e - fail (show e)));
main :: IO ();
main = do
{
putStrLn * value;
showIOS return text
(return text);
showIOS return undefined return text (return undefined
return text);
putStrLn ;
putStrLn * returned pure exception;
showIOS return undefined
(return undefined);
showIOS return (seq undefined text) (return (seq undefined
text));
showIOS return () return undefined (return () return
undefined);
showIOS return undefined = return (return undefined =
return);
putStrLn ;
putStrLn * IO failure;
showIOS fail text
(fail text);
showIOS ioError (userError text) (ioError
(userError text));
putStrLn ;
putStrLn * IO other exception;
showIOS undefined return text (undefined
return text);
showIOS return () undefined(return ()
undefined);
showIOS ioError (ErrorCall text) (ioError
(Exception.ErrorCall text));
showIOS ioError (AssertionFailed text)(ioError
(Exception.AssertionFailed text));
putStrLn ;
putStrLn * pure exception;
showIOS undefined
undefined;
showIOS seq undefined (return text) (seq undefined (return
text));
showIOS seq undefined (return undefined) (seq undefined (return
undefined));
showIOS error text(error
text);
showIOS throw (userError text)
(Exception.throw (userError text));
showIOS throw (ErrorCall text)
(Exception.throw (Exception.ErrorCall text));
showIOS throw (AssertionFailed text) (Exception.throw
(Exception.AssertionFailed text));
putStrLn ;
putStrLn * evaluate functions;
showIOS evaluate undefined
(Exception.evaluate undefined);
showIOS evaluate' undefined
RE: Prelude.catch vs. Exception.catch
At 2002-05-14 04:10, I wrote: what's the motivation for this change? Well I think it's more intuitive. FWIW, I'd like to retract this pending further investigation. I'm still not sure I fully understand how exceptions and failures work in the IO monad. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Prelude.catch vs. Exception.catch
At 2002-05-14 02:24, Simon Marlow wrote: This is bizarre: the definition of evaluate in Exception is exactly the one you gave above, yet they behave differently. You may have uncovered a compiler bug, I'll look into it. I might ask which is correct: according to the rules for seq, evaluate' undefined should be bottom, but we want Expression.evaluate undefined to be a failing IO action. I think the compiler is correct but the definition given in the documentation is wrong. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Prelude.catch vs. Exception.catch
At 2002-05-13 08:44, Simon Marlow wrote: Prelude.catch catches IO exceptions only, because this is what the Haskell report specifies. OK The idea is that if you want to use Exceptions in their full glory, you: ... import qualified Exception I've noticed something a bit unusual about Exception.catch. It seems it can't catch return undefined by itself. Consider these values of type IO String: iouPure :: IO String; iouPure = undefined; iouError :: IO String; iouError = error error; These aren't even an IO actions, they're simply bottom. Straightforward enough. But they _will_ be caught by Exception.catch. iouFail :: IO String; iouFail = fail failure; iouEvaluate :: IOString; iouEvaluate = Exception.evaluate undefined; These two are IO actions that fail when executed. They will also be caught by Exception.catch. iouReturn :: IO String; iouReturn = return undefined; This one is an IO action that succeeds when executing. It _won't_ be caught by Exception.catch, which will instead simply return the undefined value. I'm not sure what to make of this... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Prelude.catch vs. Exception.catch
I notice that Prelude.catch and Exception.catch behave differently, even
though they both have the same type signature (and name). Exception.catch
catches exceptions that Prelude.catch does not.
For instance, it is possible to bind pure functional exceptions into the
IO monad using Exception.evaluate:
peUndef :: String;
peUndef = undefined;
ioUndef :: IO String;
ioUndef = Exception.evaluate peUndef;
These can be caught with Exception.catch:
main :: IO ();
main = do
{
result - Exception.catch (ioUndef)
(\e - return (got exception: ++ (show e)));
hPutStr stderr (result ++ \n);
};
got exception: Prelude.undefined
...but not with Prelude.catch:
main :: IO ();
main = do
{
result - Prelude.catch (ioUndef)
(\e - return (got exception: ++ (show e)));
hPutStr stderr (result ++ \n);
};
Fail: Prelude.undefined
What's up with that?
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Replacing the Prelude
I have recently been experimenting writing code that replaces large chunks of the Prelude, compiling with -fno-implicit-prelude. I notice that I can happily redefine numeric literals simply by creating functions called 'fromInteger' and 'fromRational': GHC will use whatever is in scope for those names. I was hoping to do something similar for 'do' notation by redefining (), (=) etc., but unfortunately GHC is quite insistent that 'do' notation quite specifically refers to GHC.Base.Monad (i.e. Prelude.Monad, as the Report seems to require). I don't suppose there's any way of fooling it, is there? I was rather hoping 'do' notation would work like a macro in rewriting its block, and not worry about types at all. I accept that this might be a slightly bizarre request. There are a number of things I don't like about the way the Prelude.Monad class and 'do' notation are set up, and it would be nice to be able to experiment with alternatives. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
What's the '0' for in the version number?
Why is it GHC 5.02.2, 5.03 etc.? Wouldn't it be easier with 5.2.2, 5.3? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ghc-pkg info
At 2002-04-21 12:52, Sven Panne wrote: It would be nice if ghc-pkg had options to display the value of $libdir or at least the given conf file. [...] I had *major* pains with this for the upcoming HOpenGL release, too. :-P Right. I need to find the location of Rts.h. Ideally, I would do ghc-pkg -s rts --field=include_dirs ...and look in each one (if there were more than one). Unfortunately that just returns $libdir/include. It would be nice if either there were an option that expanded out the $libdir in fields, or else one that just returned $libdir. In the mean time, I'll pull it out of ghc -v... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: New Patches Binary for MacOS X
At 2002-04-15 12:29, Wolfgang Thaller wrote: The binary package for MacOS X is now available at http://www.kfunigraz.ac.at/imawww/haskell/GHC.dmg It fails to build TypedObject.hs. $ /usr/local/bin/ghc -fvia-C -pgmccc -pgmacc -package lang -package concurrent -fglasgow-exts -fallow-undecidable-instances -package-name javavm -c TypedObject.hs -o TypedObject.o +RTS -K20m stack overflow: use +RTS -Ksize to increase it TypedObject.hs is this: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/jvm-bridge/sourc e/Haskell/TypedObject.hs?rev=1.6 Actually, what I recommend you do is fetch JVM-Bridge from CVS and build it yourself. It's quite straightforward. Go here to find it: http://sourceforge.net/cvs/?group_id=32318 Follow the instructions in source/Building. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ghc-pkg info
At 2002-04-18 02:37, Wolfgang Thaller wrote: Those shell scripts were installed by a standard make install, so I expect them to be there for any platform - it has nothing to do with MacOS X. Must be a new thing in the source. Your previous port of 5.03 had symlinks there. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: adding package
At 2002-04-10 01:42, Serge D. Mechveliani wrote: I am not a system user, have not right to modify it. Please, what is the regular way out? Installing a GHC package modifies the GHC installation. You need to ask an administrator to do it, or else install your own private GHC and modify that. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Fundep/Existential Types in 5.03
At 2002-04-09 20:02, I wrote: Does anyone even know of a workaround? Given this, find an implementation of 'f' that retrieves the contents of its 'D' argument: class C a b | a - b data D a = forall b. (C a b) = MkD b f :: (C a b) = D a - b -- f (MkD b) = bwon't compile It's very annoying if it can't be done. Oh, I suppose I can always do this: data D a b = MkD b ...so perhaps in all fairness it's not quite so annoying. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Fundep/Existential Types in 5.03
Consider this: module Test3 where class C a b | a - b where m :: a - b data D a = forall b. (C a b) = MkD a f :: (C a b) = D a - b f (MkD a) = m a This compiles fine under GHC 5.02.2. But under 5.03, it gives an error: Model/Test3.hs:9: Inferred type is less polymorphic than expected Quantified type variable `b' escapes When checking an existential match that binds and whose type is D a - b1 In the definition of `f': f (MkD a) = m a I consider that the 5.02.2 behaviour is preferable, and that this is a perfectly good program. 'b' does not escape because it is fundep on 'a', which is specified in the type-signature. There can be only one. What was changed in 5.03 and why? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC for MacOS X binary - ranlib and libgmp
At 2002-03-27 01:26, Wolfgang Thaller wrote: ... and that's probably why libgmp was already installed on my system, and I never even thought about it. For now, you'll have to get it from someplace else... OK, I'll use the one in the 5.00.2 port. I'm currently attempting to build JVM-Bridge, which uses createAdjustor. I'll let you know how it works out... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC for MacOS X binary now available
At 2002-03-22 15:52, Wolfgang Thaller wrote: A tar.gz file (14.5MB) of GHC for MacOS X is now available for download at: http://www.foldr.org/Software/Haskell/ghc/ghc-5.03-13032002-MacOSX.tar.gz Do you have 'gcc' installed on your system? It's not there by default on OS X, but your GHC seems to want it. My workaround is to pass these to GHC: -pgmc cc -pgma cc -pgml cc (actually I use $(CC) instead of cc in my Makefile). Consider using 'cc' instead of 'gcc' for default programs. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Double your money in 30 days
$ ghci ___ ___ _ / _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 5.02.2, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \/\/ /_/\/|_| Type :? for help. Loading package std ... linking ... done. Prelude 0 * 2 0 -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC on MacOS X
At 2002-03-02 14:21, Wolfgang Thaller wrote: The results: another unregistered build, a PowerPC implementation of createAdjustor (foreign export dynamic now works!). Excellent! I will be porting JVM-Bridge to it as soon as it's ready. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Strictness information?
At 2002-02-19 09:21, Simon Peyton-Jones wrote: 'V' means 'eValuates'. So your function is strict in both arguments. It's intended to be internal compiler stuff which is while it's not properly documented, I'm afraid. I'd quite like to see intelligible .hi files that look like Haskell, even if they are autogenerated... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Binary Compatibility
Apologies if this has been covered before. What compatibility is there between code compiled in different versions of GHC? My JVM-Bridge was compiled under 5.02 and assembled as package 'javavm'. Will that package work if added to GHC 5.02.2? What about 5.03? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: ANNOUNCE: GHC 5.03.20020204 snapshot release
At 2002-02-05 06:36, Julian Seward (Intl Vendor) wrote: - newtypes support deriving *any* class for which the underlying type is also an instance. How about multi-parameter classes where there are instances for the underlying type on more than one parameter: is it possible to specify which parameter the newtype is being derived on? - Linear implicit parameters: a highly experimental feature. What are they? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: notes on ghc-5.02.2. Reply
At 2002-01-24 06:52, Ketil Z. Malde wrote: GHC is in Debian, you probably want to use a cutting-edge release (i.e. sid or at least woody) to be reasonably current. ghc5 in woody and sid is 5.02. If anyone would has a deb for the latest release, that would be very useful... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: question about kinds
At 2002-01-18 13:10, Hal Daume III wrote: Now, I want to say that if some data type 'd' is Traversable and another data type 'e' is Traversable, then the combined data type is Traversable. That is, for example, I want to say that a Tree of Lists is traversable, or that a List of Trees, or a List of Lists is traversable. If the Tree type constructor is Traversable, then it's Traversable no matter what it's applied to. You've provided a instance for traversing Trees of anything, it's going to overlap with any instance for Trees of Lists. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Yell
At 2002-01-12 10:22, Hal Daume III wrote: This seconds the yell. In the mean time Hugs has some documentation: http://www.cse.ogi.edu/PacSoft/projects/Hugs/pages/hugsman/exts.html#sect7. 4 -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: State Transformer
At 2002-01-11 06:18, Jorge Adriano wrote:
The whole problem is with passing the 'r' as a parameter, which is precisly
what I'm trying to avoid.
You could always pass it implicitly (using -fglasgow-exts):
--
testfunc = do
r - newSTRef ('x',0)
(do
foo
bar
with ?ref = r)
(c,n) - readSTRef r
return n
foo :: (Num a,?ref :: STRef s (Char,a)) = ST s ()
foo = do
(c,n) - readSTRef ?ref
writeSTRef ?ref ('a', n+1)
bar :: (Num a,?ref :: STRef s (t,a)) = ST s ()
bar = do
(c,n) - readSTRef ?ref
writeSTRef ?ref (c,n+2)
tryTestFunc = runST testfunc
--
Curiously, GHC isn't smart enough to infer the types of foo and bar by
itself.
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Yell
This message constitutes a yell. http://www.haskell.org/ghc/docs/latest/set/implicit-parameters.html Thanks in advance... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
ANN: Release 0.1 of Haskell/Java VM Bridge
The first release, 0.1, of Haskell/Java VM Bridge is now available. Haskell/Java VM Bridge allows Haskell programs access to the Java Virtual Machine. Features include: * On-the-fly creation of Java classes with Haskell functions for methods. * Lifted monads which do all the necessary JNI preloading and 'env'-pointer variable handling for you. These can be automatically generated via a tool (MakeJVMModule). * Integration of garbage collectors, type-class based overloading, and a tool (MakeClassModule) which uses Java reflection etc. to generate a Haskell module etc., etc. It is, however, only available for Unix and works only with GHC. This release should be 'beta' quality, but has undergone little testing. You will need: An x86 machine running some form of Unix; GHC 5.02 or later; The appropriate JVM, installed in the appropriate place: - IBM JDK/JRE 1.3 for x86, installed in /usr/lib/ibm-java/IBMJava2-13/ - Blackdown Port of Sun's JRE 1.3/Sun JDK 1.3 for x86, installed in /usr/lib/j2sdk1.3/ and /usr/lib/j2re1.3/ No documentation is currently available, sorry. Two examples have been included: a trivial hello world program, and a program that shows a Java Frame containing an instance of a Haskell-defined subclass of Canvas that has a Haskell 'paint' method that draws an oval. You should be able to figure out most of it from that... and of course the source is available from SourceForge CVS. Be sure to download the correct .tar.gz file for your Java VM. Simple installation instructions are included in the file. http://semantic.org/jvm-bridge/haskell-jvm-bridge-1_3.IBM.classic-0.1.i686 .tar.gz http://semantic.org/jvm-bridge/haskell-jvm-bridge-1_3.Blackdown.classic.na tive_threads-0.1.i686.tar.gz SourceForge's file release system is currently broken. When it's fixed, I'll put it there too. Haskell/JVM Bridge and source code is licensed under the GNU Lesser GPL. http://sourceforge.net/projects/jvm-bridge/ I hope to build an Darwin/OS X version just as soon as there's a port of GHC 5.02 with a working createAdjustor. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC 5.02.1 on Mac OS X
At 2001-12-02 14:39, Nicolas Oury wrote: do you know if there is a port of gh 5.02.1 on MacOSX? The latest I know of is GHC 5.00.2. And even that is incomplete, it doesn't seem to include a createAdjustor for 'foreign export dynamic' functions (if you happen to need that, as I do). -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
GHC Installation Location
Is there an easy way to get 'ghc' or one of the other binaries to tell me where the GHC installation directory is? I want to put the includes directory in a gcc -I flag in my makefile. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: GHC Installation Location
At 2001-10-25 03:01, Simon Marlow wrote:
I've wondered at various times in the past whether there ought to be a
link from /usr/local/includes/ghc to /usr/local/lib/ghc-5.02/includes.
Won't help, my GHC is installed at /usr/lib/ghc-5.02/, exactly where the
Debian package put it. And now that location is hard-coded in my Makefile.
But the usual way around this problem is to use 'ghc' as your C compiler
- then the -I flag gets injected automatically.
GHC didn't seem to want to compile my .cpp file -- instead it quietly and
successfully did nothing. Also I had to do this:
extern C {
#include Rts.h
}
...which I've recently entered a bug in SourceForge about.
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RE: GHC Installation Location
At 2001-10-25 03:18, Ashley Yakeley wrote: I've wondered at various times in the past whether there ought to be a link from /usr/local/includes/ghc to /usr/local/lib/ghc-5.02/includes. Won't help, my GHC is installed at /usr/lib/ghc-5.02/, exactly where the Debian package put it. Actually I suppose this means I could write #include ghc/Rts.h At 2001-10-25 09:05, Mieszko Lis wrote: I'm not sure this would be so good when you want to have two versions of ghc installed on the same machine... Currently the Debian ghc5 package installs links such as /usr/bin/ghc using the 'alternatives' system. You'd just need to add a /usr/include/ghc one to that alternatives group. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Multi-parameter OOP
At 2001-10-19 08:02, George Russell wrote: a naive user (like me a month ago) might expect that this to work, so that toBool (WrappedA a) (WrappedB b) will return False unless a is an A1, and b a B1, in which case it returns True. I think existential types are arranged so that Haskell never needs to store type information in them at run-time. So you'll never be able to do dynamic OOP with them. One possible extension to Haskell for dynamic OOP, which I never tire of suggesting, is the extensible datatype, for instance: module P data BaseType = B1 | B2 | _ module Q data DerivedType = D1 | D2 data BaseType |= BD DerivedType -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
createAdjustor on Darwin
The Darwin (Mac OS X) port of GHC 5.00.2 appears to be missing createAdjustor. As I understand it createAdjustor does some kind of architecture-specific thing with the stack, or something. Is anyone working on porting GHC 5.02 to Darwin? Will createAdjustor be included? I need it because I do dynamic exporting of callback functions through the FFI... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-10-10 01:19, I wrote: foreign import foo raw_foo :: Ptr () - IO (Ptr ()); foo :: Ptr SomeLinkedList - IO (ConstPtr Char); foo = importFunction raw_foo; Actually I don't need to convert the pointers, do I? If I have (Storable SomeLinkedList), I can just declare foreign import foo foo :: Ptr SomeLinkedList - IO (Ptr Char); and it should work. The only thing that's missing is a ConstPtr type... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
5.02 .deb?
Is there a Debian package for GHC 5.02? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-23 23:12, Manuel M. T. Chakravarty wrote: I was just hoping for GHC to be able to spit out headers for 'foreign import' functions that the user could then define. This merely means a map from some restricted set of Haskell function types to C types. Functionality like that is not part of the FFI. However, it would surely be possible to write an extra tool that accomplishes just what you want. (It was a general design rule to avoid in the basic FFI features that would be complicated to define/implement and can as easily be implemented by a tool.) Right. This would be very similar to the 'javah' tool used in the Java world. That works on compiled .class files, I suppose the equivalent would be a module that plugged in to the GHC motherboard. Moreover, the case where you bind to existing C functions is much more common than where you bind to C functions that you have written yourself. Right, but it's a more ambitious goal for the FFI designer, at least if they want to do it completely. As you point out, there are restrictions on just what existing C functions you can bind to. If your function looks like this: const char* foo (struct SomeLinkedList*); ...you have no choice but to write 'impedance-matching' code for that function. structs are not allowed as arguments to foreign imported functions. Exactly! And neither are const pointers. But argument const-ness, at least, can be safely ignored. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-23 00:45, Manuel M. T. Chakravarty wrote: No, unfortunately not. Consider, for example, that storage qualifiers would have to be generated correctly and there is no way to determine form a Haskell type whether a `const' modifier needs to be added. I would assume that Ptr types would always be mapped to non-const pointers. Do you have an example of a Haskell type for a foreign import function, for which the corresponding C function type would be ambiguous? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-23 04:02, Manuel M. T. Chakravarty wrote: I would assume that Ptr types would always be mapped to non-const pointers. Do you have an example of a Haskell type for a foreign import function, for which the corresponding C function type would be ambiguous? Take, for example, the following excerpt of the Linux man pages But do you have an example of a Haskell type for a foreign import function, for which the corresponding C function type would be ambiguous? At 2001-09-21 02:20, Manuel M. T. Chakravarty wrote: One could attempt to generate C prototypes from the Haskell type declarations or similar things, btu it doesn't work out. Surely one can still do this? This was what we were discussing, was it not? A C type for any given Haskell function type, not necessarily the other way around... -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-23 04:04, Marcin 'Qrczak' Kowalczyk wrote:
It would be impossible then to directly call a C function with a
parameter declared as a const pointer. It's illegal in C to have
mismatching prototypes of the same function.
You can always do this:
module MyModule where
{
foreign import StringCopy :: Ptr Int8 - Ptr Int8 - IO ();
}
which autogenerates this header:
extern C
{
void MyModule__StringCopy(signed char* a,signed char* b);
}
which the user can implement like this:
char* strcat(char* dest, const char* src);
void MyModule__StringCopy(char* dest,char* src)
{
strcat(dest,src);
}
(assuming char and signed char are identical).
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Re: Ptr and ForeignPtr Questions
At 2001-09-23 15:56, Marcin 'Qrczak' Kowalczyk wrote: But do you have an example of a Haskell type for a foreign import function, for which the corresponding C function type would be ambiguous? Ptr CChar (as an argument). It could be either char * or const char *. It's always char*. A Haskell function passed a Ptr CChar is not prevented from modifying the contents of the pointer simply due to its type-declaration. In C, a char* can be implicitly converted to a const char* where necessary (but not the other way around). -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Alternative Design for Finalisation
At 2001-09-21 09:40, Marcin 'Qrczak' Kowalczyk wrote: (apologies for the different spelling of finalize - apparently both are correct and I randomly settled on the 'z' version some time ago). I guess 's' is British and 'z' is American. Chambers (of Cambridge, England) has both. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-19 23:45, Manuel M. T. Chakravarty wrote:
What if the type is polymorphic (e.g.
declared as 'Storable a = Ptr a' rather than something like 'Ptr Word8')?
Also possible, as the argument to `Ptr' is just dummy.
What? What about 'withObject'? A Haskell 'Ptr a' is a C array-pointer of
whatever corresponds to 'a'. I don't think the argument is dummy.
Consider this:
int foo (char selector,char* arg)
{
if (selector == 100)
return reinterpret_castunsigned char*(arg)[1];
if (selector == 200)
return reinterpret_castunsigned short*(arg)[1];
return 0;
}
foreign import foo foo :: Storable a = Word8 - Ptr a - IO Int32;
a - withObject ([1,2] :: [Word8]) (foo 100);
b - withObject ([3,4] :: [Word16]) (foo 200);
Will this work as expected? I expect 'a' to be 2 and 'b' to be 4...
3. What about ForeignPtr? Can instances of 'Storable a = ForeignPtr a'
be used in FFI?
They can be passed to C, but you can't get them back. (The
storange manager wouldn't know what finaliser to attach.)
OK. Are ForeignPtrs intelligible in the C function as pointers to the
named type?
4. Does newForeignPtr work safely with null pointers, and will the
finalizer get called? For instance:
fp - newForeignPtr nullPtr finalFunc;
let {isNull = (foreignPtrToPtr fp) == nullPtr};
r - withForeign fp (\p - foo p);
Will foo be passed nullPtr? Will finalFunc ever get called? Is my use,
above, of foreignPtrToPtr safe, and will isNull be True?
Should work. From the storage managers point of view, a
`Ptr' is just an uninterpreted bit-pattern. A glorified
`Int'.
So you are saying that the ForeignPtr code is not interested in the
pointer-ness of the Ptr contents of a ForeignPtr, except when a
ForeignPtr is used as an FFI argument?
Presumably this also means that one can create two separate ForeignPtrs
around the same Ptr, each with their own finaliser set. Presumably they
would not be equal (note that Eq (ForeignPtr a)). Is this correct?
Also, I assume that a ForeignPtr is eligible for garbage collection
whenever it is no longer 'reachable', even if the Ptr it contains is
reachable. Is that correct?
Is there anything resembling Java's 'soft' and 'weak references'?
Of course, you should better make sure that
`finalFunc' can handle getting a `nullPtr'.
Of course...
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RE: Ptr and ForeignPtr Questions
At 2001-09-20 02:14, Simon Marlow wrote: I'll just add that the docs have been updated for 5.02, Do you have a URL for that? And don't forget that using foreignPtrToPtr is quite dangerous; much better to use withForeignPtr instead, otherwise you might find the ForeignPtr being finalised earlier than you expect. This is because foreignPtrToPtr is not in the IO monad, correct? foreignPtrToPtr :: ForeignPtr a - Ptr a; A function like this: ioForeignPtrToPtr :: ForeignPtr a - IO (Ptr a); ioForeignPtrToPtr fp = withForeignPtr fp return; ...would surely be safe? The 5.00 documentation claims that it isn't, however, but I don't see why. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-20 02:31, I wrote: int foo (char selector,char* arg) ... if (selector == 200) I guess that should be int foo (unsigned char selector,char* arg) -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: Ptr and ForeignPtr Questions
At 2001-09-20 02:46, Simon Marlow wrote: No, it's not safe. The reason is that the compiler can track a ForeignPtr to discover when it dies, in order to run the finalizer, but it can't track a Ptr. As soon as you drop all references to the ForeignPtr then the finalizer will run, even if you converted it to a Ptr and you're still using it. OK, there are different types of safety. The risk here is that the finalisers may have been called by the time you use the Ptr. But if you don't mind that, for instance, if for some reason the finalisers don't render the Ptr invalid, I assume you can still use the Ptr. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Alternative Design for Finalisation
If ForeignPtrs work the way I think they do, then I'm surprised they're designed as pointers. I believe the 'pointer' functionality is orthogonal to the 'finalisable' functionality and should be separated like this: -- data Finalisable a -- abstract handle to finalisable object instance Eq (Finalisable a); newFinalisable :: a - IO () - IO (Finalisable a); addFinaliser:: Finalisable a - IO () - IO (); withFinalisable :: Finalisable a - (a - IO b) - IO b; touchFinalisable:: Finalisable a - IO (); finalisableContents :: Finalisable a - a; type ForeignPtr a = Finalisable (Ptr a); newForeignPtr :: Ptr a- IO () - IO (ForeignPtr a); newForeignPtr = newFinalisable; addForeignPtrFinalizer :: ForeignPtr a - IO () - IO () ; addForeignPtrFinalizer = addFinaliser; withForeignPtr :: ForeignPtr a - (Ptr a - IO b) - IO b; withForeignPtr = withFinalisable; touchForeignPtr:: ForeignPtr a - IO (); touchForeignPtr = touchFinalisable; foreignPtrToPtr:: ForeignPtr a - Ptr a; foreignPtrToPtr = finalisableContents; -- I am slightly bothered by the type of finalisableContents/foreignPtrToPtr. Shouldn't it be in the IO monad? Apart from 'finalisers already run' risk, is it safe? But 'castForeignPtr' would not be definable, unless you wanted to do something like this: -- instance Functor Finalisable; castForeignPtr :: ForeignPtr a - ForeignPtr b; castForeignPtr = fmap castPtr; -- ...which I don't believe is appropriate. The only time when ForeignPtrs act like Ptrs is when they are used as FFI arguments. But I believe that's purely syntactic sugar for withForeignPtr, and would be no loss. -- foreign import foo fooFP :: ForeignPtr a - IO (); foreign import foo fooP :: Ptr a - IO (); fooFP' :: ForeignPtr a - IO (); fooFP' fp = withForeignPtr fp fooP; -- -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-20 06:55, Manuel M. T. Chakravarty wrote: The FFI does not ensure any type consistency between the arguments to `Ptr'/`ForeignPtr' and the corresponding C types. I've been using 'Ptr Word8' with newArray to pass lists of bytes to C functions. They appear as unsigned char arrays in the C function. Is this wrong, or not guaranteed? -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Ptr and ForeignPtr Questions
At 2001-09-20 19:32, Manuel M. T. Chakravarty wrote:
What I meant with the remark that you quote is that if you
would use
foreign import foo :: Ptr Int - IO Float
with
float foo (float *x)
{
return *x;
}
the system will not complain, but your program may dump
core.
What if the C looked like this:
float foo (int *x)
{
return *x;
}
...?
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Ptr and ForeignPtr Questions
The documentation for FFI in the GHC user's guide seems to be out of date
with regard to passing Ptrs across.
1. My reference is
http://www.haskell.org/ghc/docs/latest/set/ffi.html
(from http://www.haskell.org/ghc/docs/latest/set/book-users-guide.html)
Is this the latest documentation available?
2. My understanding is that you can use any instance of 'Storable a =
Ptr a' as an FFI argument and return type for both imported and exported
functions? Is this correct? What if the type is polymorphic (e.g.
declared as 'Storable a = Ptr a' rather than something like 'Ptr Word8')?
3. What about ForeignPtr? Can instances of 'Storable a = ForeignPtr a'
be used in FFI?
4. Does newForeignPtr work safely with null pointers, and will the
finalizer get called? For instance:
fp - newForeignPtr nullPtr finalFunc;
let {isNull = (foreignPtrToPtr fp) == nullPtr};
r - withForeign fp (\p - foo p);
Will foo be passed nullPtr? Will finalFunc ever get called? Is my use,
above, of foreignPtrToPtr safe, and will isNull be True?
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Converting [Word8] to CString
I'm looking for a function that will convert a [Word8] byte-array to a CString (i.e. a C byte array) for the purposes of FFI. foreign import JVMBridge JVMBridge_FindClass rawFindClass :: JavaVM - CString - IO JVMObjectRef; makeCString :: [Word8] - IO CString; It has to work correctly with _any_ list of bytes. And it has to be the _same_ list of bytes that comes through on the native side. Note that we are only dealing with bytes here, this has nothing whatever to characters, text, charsets, Unicode, encodings or any of that nonsense. If this really can't be done, is there another type I can use? In some cases, the external function may call back into Haskell. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Converting [Word8] to CString
At 2001-09-15 02:15, Marcin 'Qrczak' Kowalczyk wrote: Fri, 14 Sep 2001 23:40:42 -0700, Ashley Yakeley [EMAIL PROTECTED] pisze: I'm looking for a function that will convert a [Word8] byte-array to a CString (i.e. a C byte array) for the purposes of FFI. You can use newArray which allocates the C byte array using malloc so it must be freed by free, and cast the resulting pointer from Ptr Word8 to CString using castPtr. Thank you. I ended up doing this and simply using Ptr Word8 as the FFI type. Curiously, the GHC user's guide sec. 8.2.4.1 seems to suggest that Ptr types are illegal as arguments in foreign import function declarations. I think this is the source of my confusion. http://www.haskell.org/ghc/docs/latest/set/sec-primitive.html#SEC-PRIM-TYPE S -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC FFI Return Type Bug
At 2001-08-07 11:13, Carl R. Witty wrote: You can see that the code for f is: call g andl $255,%eax ret So gcc believes that a function which returns a value of type unsigned char is not responsible for clearing the high 3 bytes of %eax. This is to be expected; in most cases the caller will not be doing any kind of extension and so the high three bytes won't need to be masked at all. Only the caller knows whether extension is necessary, and (as Sigbjorn points out) whether it needs to do signed or unsigned extension. -- Ashley Yakeley, Seattle WA ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
GHC FFI Return Type Bug
Has anyone else come across this? I've only tried this with Word8 but I
suspect this is a problem with all return types smaller than four bytes.
I've entered this as GHC bug #448104.
http://sourceforge.net/tracker/index.php?func=detailaid=448104group_id=8
032atid=108032
Here's the C code:
extern C
{
unsigned char foo();
}
inline void use(const char* s)
{
}
unsigned char foo()
{
const char* s = ;
use(s);
return 0;
}
...and the Haskell looks something like this:
foreign import foo :: IO Word8
do {
w8 - foo;
putStrLn (show (w8 :: Word8));
}
...and the result is this:
1074803712
Kind of an unusual Word8 value! But note that the low byte of this value
is zero.
My setup:
$ ghc -v
Glasgow Haskell Compiler, Version 5.00, for Haskell 98, compiled by GHC
version 5.00
Using package config file: /usr/lib/ghc-5.00/package.conf
Hsc static flags: -static -fignore-interface-pragmas
-fomit-interface-pragmas -fdo-lambda-eta-expansion -flet-no-escape
$ uname -a
Linux server 2.2.19pre17 #1 Tue Mar 13 22:37:59 EST 2001 i686 unknown
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