[Haskell-cafe] Re: quoting in Haskell
Peter Verswyvelen wrote: In Scheme, on can quote code, so that it becomes data. Microsoft's F# and C# 3.0 also have something similar that turns code into expression trees. I can't find something similar for Haskell? Maybe I am looking at the wrong places? Quoting/Inspecting code at runtime is not possible in Haskell since this would break referential transparency, i.e. one could tell that two extensionally equal values like 3 `add` 4 1 `add` (2 `mul` 3) are different by inspecting their internal structure. Of course, you can use constructors for add and mul and then inspect and transform the result data Expr = Val Int | Add Expr Expr | Mul Expr Expr add, mul :: Expr - Expr - Expr add = Add mul = Mul x :: Expr x = Val 1 `add` (Val 2 `mul` Val 3) By making Expr an instance of the class Num , you can use overloaded arithmetic operations instance Num Expr where (+) = Add (*) = Mul fromInteger = Val . fromInteger x :: Expr x = 1 + 2*3 I want to write something like selectiveQuote [add] (1 `add` 2 `mul` 3) which would result in an expression tree like add / \ 16 So the `mul` is not quoted because it is not part of the context = [add] I'm not sure why you'd want to do that, but it's not well-defined. What would selectiveQuote [add] ((1 `add` 2) `mul` 3) be? How to expand `mul` here when `add` isn't expanded? Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [ANN] An efficient lazy suffix tree library
Bryan O'Sullivan wrote: ChrisK wrote: That is almost certainly because the algorithm expects the source string to have a unique character at its end. Chris is correct. I'll ensure that the docs make this clear. Apologies, I should have thought of this myself. Thanks. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHC 6.6.1 and SELinux issues
Hello! Does anybody here uses GHC on Linux with SELinux turned on? I've just installed SELinux and run into GHC/SELinux incompatibility. It seems that the similar problem was reported some time ago and was fixed in 6.4.3. However, I use 6.6.1 and the problem is still here. $ ghc ghc-6.6.1: internal error: getMBlock: mmap: Permission denied (GHC version 6.6.1 for i386_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Exactly the same bug is appearing on x86_64 architecture. Much more details is available at http://hackage.haskell.org/trac/ghc/ticket/738 Any ideas? With best regards, Alexander. PS. Is it possible to turn on global allow_execmem boolean in SELinux policy, thus enabling executable memory mapping. This solves the problem. However, this is major drawback for system security and should be avoided at any cost. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] [Off Topic Amusement] Lylle Lovett lyrics
http://www.lyricsdepot.com/lyle-lovett/west-texas-highway.html -- lift, the fast, powerful, easy web framework http://liftweb.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Wildly off-topic
http://importantshock.wordpress.com/2007/08/21/haskell-curry-yes-i-dated-his-daughter/ (Actually, you hardly need to click that. The URL says it all...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 6.6.1 and SELinux issues
On Tue, Aug 28, 2007 at 08:05:02AM -0600, Stuart Jansen wrote:
I'm using it on Fedora 7 without any problems.
$ ls -Z $(which ghc)
lrwxrwxrwx root root system_u:object_r:bin_t /usr/bin/ghc -
ghc-6.6.1*
$ ls -Z $(which ghci)
lrwxrwxrwx root root system_u:object_r:bin_t /usr/bin/ghci -
ghci-6.6.1*
In what domain do you run GHC? The commands about just show that
/usr/bin/ghc has the bin_t type, however it is just a symlink or shell
wrapper. Real GHC executable may have another permission.
See for example (taken from my Debian box):
$ ls -Z `which ghc`
lrwxrwxrwx root root system_u:object_r:bin_t:s0 /usr/bin/ghc -
/etc/alternatives/ghc
$ ls -Z /usr/lib/ghc-6.6.1/bin/ghc-6.6.1
-rwxr-xr-x root root system_u:object_r:bin_t:s0
/usr/lib/ghc-6.6.1/bin/ghc-6.6.1
$ file /usr/lib/ghc-6.6.1/bin/ghc-6.6.1
/usr/lib/ghc-6.6.1/bin/ghc-6.6.1: POSIX shell script text executable
$ cat /usr/lib/ghc-6.6.1/bin/ghc-6.6.1
#!/bin/sh
GHCBIN=/usr/lib/ghc-6.6.1/ghc-6.6.1;
TOPDIROPT=-B/usr/lib/ghc-6.6.1;
# Mini-driver for GHC
exec $GHCBIN $TOPDIROPT ${1+$@}
$ file /usr/lib/ghc-6.6.1/ghc-6.6.1
/usr/lib/ghc-6.6.1/ghc-6.6.1: ELF 32-bit LSB executable, Intel 80386,
version 1 (SYSV), for GNU/Linux 2.6.1, dynamically linked (uses shared
libs), stripped
$ ls -Z /usr/lib/ghc-6.6.1/ghc-6.6.1
-rwxr-xr-x root root system_u:object_r:lib_t:s0
/usr/lib/ghc-6.6.1/ghc-6.6.1
In this case the real domain for ghc is lib_t, not bin_t.
With best regards,
Alexander.
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[Haskell-cafe] Searching for a subsequence in Data.Sequence structure?
Does anyone have code for finding a subsequence within a Data.Sequence.Seq value, or is there a way to do it with the already defined instances that I am missing? A quick search didn't turn up much. Thanks in advance! Justin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ideas
Hi, Am Samstag, den 25.08.2007, 12:50 +0100 schrieb Andrew Coppin: How easy would it be to make / would anybody care / has somebody already made ... in Haskell? - A wiki program. (Ditto.) I wrote a wiki in haskell, but it focuses on full-sized LaTeX-Documents, so the “regular” wiki party is rather limited. But of course it can be extended... (It’s based on subversion, and the small CGI-part is written in python). Wiki (self-hosting): http://latexki.nomeata.de/ Application: http://mitschriebwiki.nomeata.de/ Greetings, Joachim -- Joachim nomeata Breitner mail: [EMAIL PROTECTED] | ICQ# 74513189 | GPG-Key: 4743206C JID: [EMAIL PROTECTED] | http://www.joachim-breitner.de/ Debian Developer: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] runInteractiveCommand behaves differently on linux and windows
Maybe this is by design, but I just thought I would point this behavior out and ask for comment. test1 merely shows that runInteractiveCommand reacts differently to perl warnings than perl errors. Okay, maybe the inconsistency in that case is due to perl and not haskell. test2 behaves the same on win and nix. This is pipe like in that the ouptut of a command (which could be the result of a shell call, but just as easily be the return of a haskell function) gets fed into a shell command. In this case, if the shell command is simply tail the behavior is consistent from win to nix. test3 shows that the behavior stops being consistent if ssh enters the picture. (piping to tail via ssh). again, maybe this is due to ssh and not haskell. however... note however that on windows ghc -e 'mapM_ ( putStrLn . show ) [1..1000] ' | ssh [EMAIL PROTECTED] 'tail -n2' works fine. so it's not *just* ssh, but ssh in conjuction with runInteractiveCommand which seems to cause problems FWIW, using 10 lines instead of 1000 still hangs on windows. Is there a way to code up shell pipelike behavior in a more portable way? curious what the cafe thinks... thomas. import Test.HUnit import Misc ( (=^) ) import System.Process import System.IO import System.Exit -- works on linux, error on windows test1 = do res1 - test_shellrunStderrOk runTestTT $ TestCase ( assertEqual test1 made it res1 ) where test_shellrunStderrOk = do runprocessStdErrAllowed' cmdPerlwarn return made it cmdPerldie = perl -e 'die \error\' cmdPerlwarn = perl -e 'warn \blee\' -- works on linux, windows test2 = pipeTo tail -n2 -- works on linux, hangs on windows test3 = pipeTo ssh [EMAIL PROTECTED] 'tail -n2' pipeTo cmd = do res2 - test_shellrunPipeinLike runTestTT $ TestCase ( assertEqual ( pipe to, cmd: ++ cmd) (show l) res2 ) where test_shellrunPipeinLike = do runprocessStdErrAllowed' (unlines $ map show [1..l]) ( cmd ) =^ filter (not . ( == '\n') ) l = 1000 runprocessStdErrAllowed' inp s = do (ih,oh,eh,pid) - runInteractiveCommand s so - hGetContents oh se - hGetContents eh hPutStrLn ih inp hClose ih ex - waitForProcess pid case ex of ExitFailure e - fail $ shell command ++ s ++ \nFailed with status: ++ show e _ | otherwise - return so --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal install of HDBC-odbc fails on ghc 6.7, -I flag causes problems
Well, I built with -v3 as suggested, but the ouptut doesn't seem that
helpful to me. ghc compile commands, at any rate, do not appear to be
outputted
$ echo :main build | /usr/local/bin/ghci-6.7.20070816 -v3 Setup.hs
1build.out 2build.err
build.out:
GHCi, version 6.7.20070816: http://www.haskell.org/ghc/ :? for help
Loading package base ... linking ... done.
Ok, modules loaded: Main.
*Main Loading package array-0.1 ... linking ... done.
Loading package containers-0.1 ... linking ... done.
Loading package old-locale-1.0 ... linking ... done.
Loading package old-time-1.0 ... linking ... done.
Loading package filepath-1.0 ... linking ... done.
Loading package directory-1.0 ... linking ... done.
Loading package unix-2.0 ... linking ... done.
Loading package process-1.0 ... linking ... done.
Loading package pretty-1.0 ... linking ... done.
Loading package Cabal-1.1.7 ... linking ... done.
Reading parameters from
/home/hartthoma/installs/HDBC-odbc-1.0.1.0/HDBC-odbc.buildinfo
Preprocessing library HDBC-odbc-1.0.1.0...
*** Exception: exit: ExitFailure 1
*Main Leaving GHCi.
build.err:
Glasgow Haskell Compiler, Version 6.7.20070816, for Haskell 98, stage 2
booted by GHC version 6.6.1
Using package config file: /usr/local/lib/ghc-6.7.20070816/package.conf
hiding package regex-base-0.72 to avoid conflict with later version
regex-base-0.91
hiding package HDBC-1.0.1 to avoid conflict with later version HDBC-1.1.2
wired-in package base mapped to base-2.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-0.1
wired-in package ndp not found.
Hsc static flags: -static
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
*** Chasing dependencies:
Chasing modules from:
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
Ready for upsweep []
Upsweep completely successful.
*** Deleting temp files:
Deleting:
*** Chasing dependencies:
Chasing modules from: Setup.hs
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
Ready for upsweep
[NONREC
ModSummary {
ms_hs_date = Mon Aug 20 09:49:47 EDT 2007
ms_mod = main:Main,
ms_imps = [System.Exit, Distribution.PackageDescription,
Distribution.Simple.Utils, Data.List, System.Info,
Distribution.Simple]
ms_srcimps = []
}]
compile: input file Setup.hs
*** Checking old interface for main:Main:
[1 of 1] Compiling Main ( Setup.hs, interpreted )
*** Parser:
*** Renamer/typechecker:
*** Desugar:
Result size = 435
*** Simplify:
Result size = 464
Result size = 437
*** Tidy Core:
Result size = 437
*** CorePrep:
Result size = 491
*** ByteCodeGen:
*** Deleting temp files:
Deleting:
Upsweep completely successful.
*** Deleting temp files:
Deleting:
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
ghc-6.6.1: unrecognised flags: -I
Usage: For basic information, try the `--help' option.
compiling dist/build/Database/HDBC/ODBC/Connection_hsc_make.c failed
command was: ghc -c -I dist/build/Database/HDBC/ODBC/Connection_hsc_make.c
-o dist/build/Database/HDBC/ODBC/Connection_hsc_make.o
*** Deleting temp files:
Deleting:
*** Deleting temp dirs:
Deleting:
Duncan Coutts [EMAIL PROTECTED]
08/22/2007 04:53 PM
To
Thomas Hartman/ext/[EMAIL PROTECTED]
cc
haskell-cafe@haskell.org
Subject
Re: [Haskell-cafe] cabal install of HDBC-odbc fails on ghc 6.7, -I flag
causes problems
On Mon, 2007-08-20 at 13:10 -0400, Thomas Hartman wrote:
problemw with the -I flag to ghc are causing cabal install to fail for
hdbc-odbc (darcs head).
Any tips on debugging this cabal install would be appreciated.
$ runghc Setup.hs configure; runghc Setup.hs build
Try with -v3 is:
runghc Setup.hs build -v3
this will give extremely verbose output. We'd like to see the last bit
to see what ghc command line exactly is failing. It'll show the command
line arguments in Haskell show format eg [-I, /]
Duncan
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Re: [Haskell-cafe] cabal install of HDBC-odbc fails on ghc 6.7, -I flag causes problems
On Tue, 2007-08-28 at 18:19 -0400, Thomas Hartman wrote: Well, I built with -v3 as suggested, but the ouptut doesn't seem that helpful to me. ghc compile commands, at any rate, do not appear to be outputted Sorry, I meant to pass -v3 to cabal, not to ghc compiling/running Setup.hs $ echo :main build | /usr/local/bin/ghci-6.7.20070816 -v3 Setup.hs 1build.out 2build.err like: runghc Setup.hs build -v3 Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Norvig's Sudoku Solver in Haskell
chaddai.fouche: For the translation of the above OCaml code, there is not much to do, in fact it is mostly functional, and so easily translated in Haskell code, note that I add a code to handle input of the form 4.8.5.3..7..2.6.8.4..1...6.3.7.5..2.1.4.., to resolve it and print a solution : Spencer Janssen also wrote a rather elegant translation, which you can find on hpaste.org import Data.List import Data.Ord n = 3 :: Int invalid (i, j) (i', j') = i == i' || j == j' || i `div` n == i' `div` n j `div` n == j' `div` n select p n p' ns | invalid p p' = filter (/= n) ns | otherwise= ns add p n sols = sortBy (comparing (length . snd)) $ map f sols where f (p', ns) = (p', select p n p' ns) search [] = [[]] search ((p, ns):sols) = [(p, n):ss | n - ns, ss - search $ add p n sols] You can see the development here, http://hpaste.org/2348 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Serial Communications in Haskell
I'm on a Windows box and I'm looking for a way to talk to a serial port (for example, RS-232) from Haskell. I couldn't find a library to do this, so I am wondering how to create one. I have a fairly thorough understanding of how to open and use a serial port with the Windows API. In particular, to open a serial port, I have to use CreateFile, which is the same API call that opens files. In fact, if I call openFile from GHC, and pass COM1: as the filename, then I can get a writable serial port. module Serial where import System.IO main = do h - openFile COM1: ReadWriteMode hPutStrLn h Hello World I can't read from the port (I always get an immediate EOF), and I have no way of configuring things like the baud rate or the parity settings. Nevertheless, this demonstrates that openFile can at least open the serial port. What I would like to do is create some functions that would allow me to open and configure a serial port, and get a Handle back so that I can use the existing IO functions like hGetChar and hPutChar. I am assuming that hGetChar eventually calls win32::ReadFile and hPutChar eventually calls win32::WriteFile. These same two API calls would work for serial ports. In Windows, there are 23 API functions that apply specifically to serial ports. Out of these 23 functions, only a few of them are actually necessary if I just want to send and receive data. Of course, I don't know how to call Windows API functions from Haskell, and I have no idea how to hook things to the IO library so that I can use a Handle for a serial port. I'm looking for some advice on how to proceed. -- Ron ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
