- Glasgow-haskell-users

"eval" in ghc(i)?
by Geoffrey Alan Washburn 06 May '06

06 May '06

I have an application written in OCaml that I'm interested in porting over to Haskell, and I was wondering what the best way to replace the following OCaml function would be: Toploop.initialize_toplevel_env();; let eval txt = let lb = (Lexing.from_string txt) in let phr = !Toploop.parse_toplevel_phrase lb in Toploop.execute_phrase true Format.std_formatter phr;; eval "let add1 x = x +1;;";; eval "add1 2;;";; Where I would like to be able to "eval" Haskell-code instead. It looks like I might be able to achieve something like this using hs-plugins, but it looks a bit more complex. Is hs-plugins the best choice for this kind of "meta"-programming? I'm pretty sure Template Haskell will not work for me, at least as I understand it I can only manipulate program fragments that will be compiled later and as such that it will not be possible to execute them until the next "phase".

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deriving existential types
by Marc Weber 04 May '06

04 May '06

I sometimes do this -< class (Show c) => C c where foo = show c data CObj= forall c. (C c, Show c) => CObj c instance C Cobj where -- my existantial type should also implement class C foo (CObj c) = foo c -> Would it be a nice idea to just write -< data CObj= forall c. (C c, Show c) => CObj c deriving (C) ? -> ? Or is this already possible? Marc Weber

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import prefers module in package over local module
by Michael Marte 04 May '06

04 May '06

Hello *, I am migrating a project from ghc 6.2 to ghc 6.4. This project has a module called Pretty and that's where my problems start. When importing Pretty, ghc does not consider my local definition but the Pretty module from the standard library (which is an alias for Text.PrettyPrint.HughesPJ). Is this behaviour intended or is it a bug? Can I change it? If it is intended, can somebody explain the rationale to me? BTW, I am using -hidir and -odir and the latest Debian package containing ghc 6.4.1. Thank you, Michael

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Building ghc-6.4 on Solaris x86
by Georg Sauthoff 03 May '06

03 May '06

Hi, I am trying to build ghc-6.4.2 under solaris x86 (10.0). I mainly followed http://www.haskell.org/ghc/docs/latest/html/building/sec-porting-ghc.html, but now I am stuck. I managed to build an unregistered ghc at the target. I build the .hc files on a x86 Linux box. It compiles hello world .hs programs fine. This are the steps I am using to build the ghc with the unregistered build: PATH=/var/tmp/gsauthof/bin:/usr/sfw/bin:$PATH ./configure --with-gcc=/usr/sfw/bin/gcc --with-ghc="/var/tmp/gsauthof/src/ghc-6.4.2/ghc/compiler/ghc-inplace" --prefix=/var/tmp/gsauthof/ghc-6.4.2 2>&1 | tee log PATH=/var/tmp/gsauthof/bin:/usr/sfw/bin:$PATH make 2>&1 | tee log2 After some minutes the build process stops, i.e. in top I see a 0.2% consuming ghc and no more output, the last one is: ../../ghc/compiler/ghc-inplace -optc-O -optc-Wall -optc-W -optc-Wstrict-prototypes -optc-Wmissing-prototypes -optc-Wmissing-declarations -optc-Winline -optc-Waggregate-return -optc-Wbad-function-cast -optc-I../includes -optc-I. -optc-Iparallel -optc-DCOMPILING_RTS -optc-fomit-frame-pointer -optc-Wno-uninitialized -H16m -O -O2 -static -I. -#include Prelude.h -#include Rts.h -#include RtsFlags.h -#include RtsUtils.h -#include StgRun.h -#include Schedule.h -#include Printer.h -#include Sanity.h -#include STM.h -#include Storage.h -#include SchedAPI.h -#include Timer.h -#include Itimer.h -#include ProfHeap.h -#include LdvProfile.h -#include Profiling.h -#include Apply.h -fvia-C -dcmm-lint -c GC.c -o GC.o If I go into ghc/rts and manually execute the last command, it terminates sometimes. I.e. if I execute it manually 20 times, 1 time it hangs and 19 times it terminates ... Is this a known problem? While building at the target I noticed some minor things: - ctime_r from time.h at solaris without posix define is not posix conform; configure could check this (dumb patch attached) - a whitespace problem in mk/target.mk (simple patch attached) (I got: /bin/sh: syntax error at line 1: `;' unexpected) - I get a link error because of the missing symbol yield_sched (see dumb patch) - I missed a --disable-readline switch While building the unregistered version: - /usr/sfw/bin/gcc -o stage1/ghc-6.4.2 -fno-defer-pop -fomit-frame-pointer -DNO_REGS -DUSE_MINIINTERPRETER -DDONT_WANT_WIN32_DLL_SUPPORT -D_ ... ld: fatal: library -lghccompat: not found => SUBDIRS = includes rts docs compiler lib utils driver switched docs and lib - make: *** No rule to make target `Compat/Directory.o', needed by `libghccompat.a'. Stop. => at the host at H/ghc/lib/compat instead make boot UseStage1=YES execute make boot UseStage1=YES EXTRA_HC_OPTS='-O -fvia-C -keep-hc-files' and get the .hc files, too - I missed a --disable-opengl switch While trying to build a registered version: - configure does not check im 'as' is a GNU as - e.g. the solaris as rejects some asm source, gas accepts (i.e. Illegal subtraction - symbols from different sections); configure could check this and provide a --with-as switch Regards Georg Sauthoff

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On GHC HEAD, Fefora Cote 5 and SELinux
by wld 03 May '06

03 May '06

As described in trac ticket 738, GHC HEAD does not work on Fedora Core 5 with selinux in enforcing mode. Selinux is the additional level of protection in Linux kernel that works above usual Unix permissions. Turning selinux to permissive mode (as suggested in the workaround to make GHC work) actually disables *all* protection. I think, many users of FC5 do not see it as workaround at all. I found a much lighter workaround - just to allow processes to execute in heap. In GUI: Menu System -> Administration -> Security Level and Firewall -> tab SELinux, in the tree control open an item Other turn on allow_execheap On command line (as root): setsebool -P allow_execheap 1 There are three related "booleans" to try (just in case the trick above does not help) allow_execmem allow_execmod allow_execstack PS. This works for the targeted selinux policy, which is default in Fedora 5. There are also strict and mls policies. I am not selinux guru -I do not know if my workaround works for those policies. V.Rudenko -- lambda is the ultimate

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RE: [Haskell] (GHC) Boot files and instance declarations
by Simon Peyton-Jones 03 May '06

03 May '06

At the moment GHC just doesn't support this, I'm afraid. It's a shortcoming, and one that could be fixed, but not in a minute or two. You'll have to find some other way to reorganise your code, I think. Incidentally questions specific to GHC belong on ghc-users, to which I have redirected this message Simon | -----Original Message----- | From: haskell-bounces(a)haskell.org [mailto:haskell-bounces@haskell.org] On Behalf Of David House | Sent: 02 May 2006 21:36 | To: haskell(a)haskell.org | Subject: [Haskell] (GHC) Boot files and instance declarations | | Hi all. A quick bootfiles question. | | The GHC docs specify not to put instance decls in bootfiles. However, | what if i need to? For example, say I have a module A where I'm | importing a module B with the {-# SOURCE #-} pragma. Module A needs to | know that the types in module B are instances of some typeclasses | (instance declarations for which are given in module B). How would I | manage this? | | Thanks in advance. | | -- | -David House, dmhouse(a)gmail.com, http://xmouse.ithium.net | _______________________________________________ | Haskell mailing list | Haskell(a)haskell.org | http://www.haskell.org/mailman/listinfo/haskell

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ANNOUNCE: GHC vesrion 6.4.2
by Simon Marlow 02 May '06

02 May '06

============================================================= The (Interactive) Glasgow Haskell Compiler -- version 6.4.2 ============================================================= The GHC Team is pleased to announce a new patchlevel release of GHC. This release contains a significant number of bugfixes relative to 6.4.1, so we recommend upgrading. Highlights in this release: - Cabal has been upgraded to version 1.1.4. While strictly speaking this breaks our rules about not changing any library APIs in a patchlevel release, it was felt that the Cabal shipped in 6.4.1 was lacking in various ways, and it was more important to provide a Cabal that works with more existing packages. Some distributions of GHC were already supplying an upgraded Cabal by default. With the exception of Cabal, and OpenAL which was also upgraded, all library APIs are identical to 6.4.1. Release notes are here: http://haskell.org/ghc/docs/6.4.2/html/users_guide/release-6-4-2.html How to get it ~~~~~~~~~~~~~ The easy way is to go to the web page, which should be self-explanatory: http://www.haskell.org/ghc/ We supply binary builds in the native package format for many platforms, and the source distribution is available from the same place. Packages will appear as they are built - if the package for your system isn't available yet, please try again later. Background ~~~~~~~~~~ Haskell is a standard lazy functional programming language; the current language version is Haskell 98, agreed in December 1998 and revised December 2002. GHC is a state-of-the-art programming suite for Haskell. Included is an optimising compiler generating good code for a variety of platforms, together with an interactive system for convenient, quick development. The distribution includes space and time profiling facilities, a large collection of libraries, and support for various language extensions, including concurrency, exceptions, and foreign language interfaces (C, whatever). GHC is distributed under a BSD-style open source license. A wide variety of Haskell related resources (tutorials, libraries, specifications, documentation, compilers, interpreters, references, contact information, links to research groups) are available from the Haskell home page (see below). On-line GHC-related resources ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Relevant URLs on the World-Wide Web: GHC home page http://www.haskell.org/ghc/ GHC developers' home page http://hackage.haskell.org/trac/ghc/ Haskell home page http://www.haskell.org/ Supported Platforms ~~~~~~~~~~~~~~~~~~~ The list of platforms we support, and the people responsible for them, is here: http://hackage.haskell.org/trac/ghc/wiki/Contributors Ports to other platforms are possible with varying degrees of difficulty. The Building Guide describes how to go about porting to a new platform: http://www.haskell.org/ghc/docs/latest/html/building/building-guide.html Developers ~~~~~~~~~~ We welcome new contributors. Instructions on accessing our source code repository, and getting started with hacking on GHC, are available from the GHC's developer's site run by Trac: http://hackage.haskell.org/trac/ghc/ Mailing lists ~~~~~~~~~~~~~ We run mailing lists for GHC users and bug reports; to subscribe, use the web interfaces at http://www.haskell.org/mailman/listinfo/glasgow-haskell-users http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs There are several other haskell and ghc-related mailing lists on www.haskell.org; for the full list, see http://www.haskell.org/mailman/listinfo/ GHC developers occasionally hang out on #haskell on IRC, too: http://www.haskell.org/haskellwiki/IRC_channel Please report bugs using our bug tracking system. Instructions on reporting bugs can be found here: http://www.haskell.org/ghc/reportabug

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Dynamic Programming with Memoizing
by Lajos Nagy 29 Apr '06

29 Apr '06

Well, I got stuck. I wanted to use dynamic programming to compute the value `p 100': ================================ module Main where import Data.Ratio import Data.Ix n = 100 q :: (Integer, Integer) -> Rational q (i,k) | i == 1 && k == 2 = 1 q (i,k) = (map q' (range dom)) !! (dom `index` (i,k)) where dom = ((1,1),(n,n)) q' (i,k) = (p i * ((n + 1 - k) % 1)) / ((n + 1 - i) % 1) p :: Integer -> Rational p k | k == 1 = 1 p k = map p' [1 .. n] !! ((1,n) `index` k) where p' k = sum (map f [1 .. (k - 1)]) where f i = q (i,k) / ((n + 1 - i) % 1) ====================== I used the lazy list pattern for memoizing previous values of `p' and `q' as I saw it elsewhere. Both `p k' and `q (i,k)' depend only on values of `p x' and `q (y,x)' where `x < k' and `y < k'. Nevertheless, it takes forever to compute even `p 20'. What's wrong? (I even tried using a strict container along the lines of `N !Rational' for storing the results of `p' and `q'. It didn't help.) The program seems to work correctly for small values of `k', by the way. I used Rational because I needed the _exact_ result. Thanks and Regards, -- Lajos Nagy Computer Science Ph.D. Student, Florida Institute of Technology

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cvs-head compile question
by jur 28 Apr '06

28 Apr '06

Hi there, when I compile the head I get this message /usr/bin/ld: Undefined symbols: _ding _free_undo_list _rl_add_undo _rl_basic_quote_characters _rl_begin_undo_group _rl_bind_key_in_map _rl_binding_keymap _rl_char_is_quoted_p _rl_clear_message _rl_clear_signals _rl_complete_internal _rl_copy_keymap _rl_copy_text _rl_delete_text _rl_directory_completion_hook _rl_discard_keymap _rl_do_undo _rl_end_undo_group _rl_executing_keymap _rl_filename_dequoting_function _rl_filename_quote_characters _rl_filename_quoting_desired _rl_filename_quoting_function _rl_forced_update_display _rl_function_dumper _rl_function_of_keyseq _rl_generic_bind _rl_get_keymap _rl_get_keymap_by_name _rl_get_keymap_name _rl_ignore_some_completions_function _rl_insert_completions _rl_insert_text _rl_kill_text _rl_list_funmap_names _rl_make_bare_keymap _rl_make_keymap _rl_mark _rl_modifying _rl_named_function _rl_on_new_line _rl_pending_input _rl_possible_completions _rl_reset_line_state _rl_set_keymap _rl_set_signals _rl_unbind_command_in_map _rl_unbind_key _rl_unbind_key_in_map _rl_message collect2: ld returned 1 exit status <<ghc: 32089144 bytes, 4 GCs, 95456/95456 avg/max bytes residency (1 samples), 16M in use, 0.03 INIT (0.00 elapsed), 0.51 MUT (33.23 elapsed), 0.07 GC (0.26 elapsed) :ghc>> make[2]: *** [stage2/ghc-6.5] Error 1 make[1]: *** [stage2] Error 2 make: *** [bootstrap2] Error 2 So what am I missing. Is it GTK+2? Do I really need it? Is there some way to compile the compiler without needing to bother with this? thanks, Jur

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Re[2]: [GHC] #710: library reorganisation
by Bulat Ziganshin 28 Apr '06

28 Apr '06

Hello GHC, {- answering message in ghc-bugs -} Thursday, April 27, 2006, 2:06:07 PM, you wrote: > #710: library reorganisation >> Some libraries we want to add: >> >> * [http://www.cse.unsw.edu.au/~dons/fps.html FastPackedStrings] >> (replace {{{Data.PackedString}}}) sorry for repetition, but ByteString library in its current state still don't replaces PackedString in functionality, because it don't support full Unicode range of chars -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com

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