Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
Well, that was probably the main problem :-( Unfortunately, even if, after performing all the stuff once again, I made platform configured, make ended in compilation of happy with old story: Configuring happy-1.18.5... ./Setup build Preprocessing executables for happy-1.18.5... Building happy-1.18.5... ghc: could not execute: /usr/bin/gcc Error: Building the happy-1.18.5 package failed make: *** [build.stamp] Error 2 Even if all other items went OK, until happy :-( and it is called happy ;-) :-D Dusan On 02/08/2011 04:48 PM, Christian Maeder wrote: What does gcc -v say? Maybe you have to install the 32Bit ghc-6.12.3 that can work together with your gcc. Christian Am 08.02.2011 15:05, schrieb Kolar Dusan: No :-( D. There seems to be confusion about 32bit and 64bit assembly. Can you compile and link without optimization? C. Am 08.02.2011 13:33, schrieb Dušan Kolář: Well, it helped, but not getting output anyway: /tmp/ghc32376_0/ghc32376_0.s: Assembler messages: /tmp/ghc32376_0/ghc32376_0.s:35:0: Error: bad register name `%rbp)' /tmp/ghc32376_0/ghc32376_0.s:36:0: Error: bad register name `%r15' /tmp/ghc32376_0/ghc32376_0.s:38:0: Error: bad register name `%r12' /tmp/ghc32376_0/ghc32376_0.s:39:0: Error: bad register name `%r13)' /tmp/ghc32376_0/ghc32376_0.s:41:0: Error: bad register name `%r12)' /tmp/ghc32376_0/ghc32376_0.s:42:0: Error: bad register name `%rbx' ... and many other similar lines Is my installation of gcc broken? :-O ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
I have the following ghc script:
cat ghc
#!/bin/sh
exedir=/usr/local/lib/ghc-6.12i386/lib/ghc-6.12.3
exeprog=ghc-stage2
executablename=$exedir/$exeprog
datadir=/usr/local/lib/ghc-6.12i386/share
bindir=/usr/local/lib/ghc-6.12i386/bin
topdir=/usr/local/lib/ghc-6.12i386/lib/ghc-6.12.3
pgmgcc=/usr/local/bin/gcc
executablename=$exedir/ghc
exec $executablename -B$topdir -pgmc $pgmgcc -pgml $pgmgcc
-pgma $pgmgcc ${1+$@}
Dušan
On 02/10/2011 04:38 PM, Christian Maeder wrote:
Am 10.02.2011 13:15, schrieb Dušan Kolář:
Well, that was probably the main problem :-(
Unfortunately, even if, after performing all the stuff once again, I
made platform configured, make ended in compilation of happy with old
story:
Configuring happy-1.18.5...
./Setup build
Preprocessing executables for happy-1.18.5...
Building happy-1.18.5...
ghc: could not execute: /usr/bin/gcc
Error:
Building the happy-1.18.5 package failed
make: *** [build.stamp] Error 2
Maybe this time indeed gcc is called as linker and you should add
-pgml /usr/local/bin/gcc
In fact my ghc script for ghc-7.0.1 contains:
pgmgcc=/usr/bin/gcc
executablename=$exedir/ghc
exec $executablename -B$topdir -pgmc $pgmgcc -pgma $pgmgcc -pgml
$pgmgcc -pgmP $pgmgcc -E -undef -traditional ${1+$@}
Christian
Even if all other items went OK, until happy :-( and it is called happy
;-) :-D
Dusan
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[Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
Hello all, I'm trying to build platform on Linux 2.6.32.22 #1 SMP Tue Sep 21 09:44:04 CEST 2010 x86_64 x86_64 x86_64 GNU/Linux. I've downloaded binary of ghc6.12.3 for the purpose, but ghc doesn't work. ghci does work, gcc does work, but for ghc I get: ghc -O2 --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) ghc: could not execute: /usr/bin/gcc Even if I can easily compile gcc testc.c -o testc and run testc. Could anyone point me to a solution? Helps found by google pointed me to try use option -pgmc gcc, which doesn't work. All other threads with similar issue stayed unresoleved. :-( Thanks Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
Not the problem, ghc script:
cat /usr/local/lib/ghc-6.10.4/V12/bin/ghc
#!/bin/sh
exedir=/usr/local/lib/ghc-6.10.4/V12//lib/ghc-6.12.3
exeprog=ghc-stage2
executablename=$exedir/$exeprog
datadir=/usr/local/lib/ghc-6.10.4/V12/share
bindir=/usr/local/lib/ghc-6.10.4/V12/bin
topdir=/usr/local/lib/ghc-6.10.4/V12/lib/ghc-6.12.3
pgmgcc=/usr/local/bin/gcc
executablename=$exedir/ghc
exec $executablename -B$topdir -pgmc $pgmgcc ${1+$@}
while:
which gcc
/usr/local/bin/gcc
Dusan
On 02/08/2011 12:42 PM, Christian Maeder wrote:
Am 08.02.2011 11:39, schrieb Dušan Kolář:
ghc -O2 --make test.hs -o test
[1 of 1] Compiling Main ( test.hs, test.o )
ghc: could not execute: /usr/bin/gcc
Even if I can easily compile gcc testc.c -o testc and run testc.
Your ghc script (under /usr/local/bin or elsewhere type -all ghc)
contains a line:
pgmgcc=/usr/bin/gcc
This line should be corrected to point to your gcc that is probably not
under /usr/bin/. Try by which gcc or type -all gcc.
(The official binaries only work for sane systems.)
HTH Christian
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Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
Unfortunately, no help :-(
String /usr/bin/gcc was found in the following files, if it is useful
information:
/lib/ghc-6.12.3/haddock
/lib/ghc-6.12.3/ghc
/lib/ghc-6.12.3/ghc-6.12.3/Config.hi
/lib/ghc-6.12.3/ghc-6.12.3/Config.p_hi
/lib/ghc-6.12.3/ghc-6.12.3/Config.dyn_hi
/lib/ghc-6.12.3/ghc-6.12.3/libHSghc-6.12.3.a
/lib/ghc-6.12.3/ghc-6.12.3/libHSghc-6.12.3_p.a
/lib/ghc-6.12.3/ghc-6.12.3/HSghc-6.12.3.o
/lib/ghc-6.12.3/ghc-6.12.3/libHSghc-6.12.3-ghc6.12.3.so
+doc files
Dusan
On 02/08/2011 12:56 PM, Christian Maeder wrote:
Ok, gcc is used as linker, too. So maybe try to
-pgml /usr/local/bin/gcc
add to your command line.
C.
Am 08.02.2011 12:50, schrieb Dušan Kolář:
Not the problem, ghc script:
cat /usr/local/lib/ghc-6.10.4/V12/bin/ghc
#!/bin/sh
exedir=/usr/local/lib/ghc-6.10.4/V12//lib/ghc-6.12.3
exeprog=ghc-stage2
executablename=$exedir/$exeprog
datadir=/usr/local/lib/ghc-6.10.4/V12/share
bindir=/usr/local/lib/ghc-6.10.4/V12/bin
topdir=/usr/local/lib/ghc-6.10.4/V12/lib/ghc-6.12.3
pgmgcc=/usr/local/bin/gcc
executablename=$exedir/ghc
exec $executablename -B$topdir -pgmc $pgmgcc ${1+$@}
while:
which gcc
/usr/local/bin/gcc
Dusan
On 02/08/2011 12:42 PM, Christian Maeder wrote:
Am 08.02.2011 11:39, schrieb Dušan Kolář:
ghc -O2 --make test.hs -o test
[1 of 1] Compiling Main ( test.hs, test.o )
ghc: could not execute: /usr/bin/gcc
Even if I can easily compile gcc testc.c -o testc and run testc.
Your ghc script (under /usr/local/bin or elsewhere type -all ghc)
contains a line:
pgmgcc=/usr/bin/gcc
This line should be corrected to point to your gcc that is probably not
under /usr/bin/. Try by which gcc or type -all gcc.
(The official binaries only work for sane systems.)
HTH Christian
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Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
This is the end of the log: *** Assembler: /usr/bin/gcc -I. -c /tmp/ghc29474_0/ghc29474_0.s -o test.o *** Deleting temp files: Deleting: /tmp/ghc29474_0/ghc29474_0.s *** Deleting temp dirs: Deleting: /tmp/ghc29474_0 ghc: could not execute: /usr/bin/gcc Otherwise gcc not mentioned, no error mentioned. Dusan On 02/08/2011 01:04 PM, Christian Maeder wrote: Does adding -v reveal when /usr/bin/gcc is used? ghc -v -O2 --make test.hs -o test C. Am 08.02.2011 11:39, schrieb Dušan Kolář: Hello all, I'm trying to build platform on Linux 2.6.32.22 #1 SMP Tue Sep 21 09:44:04 CEST 2010 x86_64 x86_64 x86_64 GNU/Linux. I've downloaded binary of ghc6.12.3 for the purpose, but ghc doesn't work. ghci does work, gcc does work, but for ghc I get: ghc -O2 --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) ghc: could not execute: /usr/bin/gcc Even if I can easily compile gcc testc.c -o testc and run testc. Could anyone point me to a solution? Helps found by google pointed me to try use option -pgmc gcc, which doesn't work. All other threads with similar issue stayed unresoleved. :-( Thanks Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Building Plaftorm 2010 2 on 64bit Linux
Well, it helped, but not getting output anyway: /tmp/ghc32376_0/ghc32376_0.s: Assembler messages: /tmp/ghc32376_0/ghc32376_0.s:35:0: Error: bad register name `%rbp)' /tmp/ghc32376_0/ghc32376_0.s:36:0: Error: bad register name `%r15' /tmp/ghc32376_0/ghc32376_0.s:38:0: Error: bad register name `%r12' /tmp/ghc32376_0/ghc32376_0.s:39:0: Error: bad register name `%r13)' /tmp/ghc32376_0/ghc32376_0.s:41:0: Error: bad register name `%r12)' /tmp/ghc32376_0/ghc32376_0.s:42:0: Error: bad register name `%rbx' ... and many other similar lines Is my installation of gcc broken? :-O Dusan On 02/08/2011 01:27 PM, Christian Maeder wrote: This looks like gcc is used as assembler. Try to add: -pgma /usr/local/bin/gcc C. Am 08.02.2011 13:22, schrieb Dušan Kolář: This is the end of the log: *** Assembler: /usr/bin/gcc -I. -c /tmp/ghc29474_0/ghc29474_0.s -o test.o *** Deleting temp files: Deleting: /tmp/ghc29474_0/ghc29474_0.s *** Deleting temp dirs: Deleting: /tmp/ghc29474_0 ghc: could not execute: /usr/bin/gcc Otherwise gcc not mentioned, no error mentioned. Dusan On 02/08/2011 01:04 PM, Christian Maeder wrote: Does adding -v reveal when /usr/bin/gcc is used? ghc -v -O2 --make test.hs -o test C. Am 08.02.2011 11:39, schrieb Dušan Kolář: Hello all, I'm trying to build platform on Linux 2.6.32.22 #1 SMP Tue Sep 21 09:44:04 CEST 2010 x86_64 x86_64 x86_64 GNU/Linux. I've downloaded binary of ghc6.12.3 for the purpose, but ghc doesn't work. ghci does work, gcc does work, but for ghc I get: ghc -O2 --make test.hs -o test [1 of 1] Compiling Main ( test.hs, test.o ) ghc: could not execute: /usr/bin/gcc Even if I can easily compile gcc testc.c -o testc and run testc. Could anyone point me to a solution? Helps found by google pointed me to try use option -pgmc gcc, which doesn't work. All other threads with similar issue stayed unresoleved. :-( Thanks Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is EclipseFP alive?
Hello, I tried to install EclipseFP using instructions on http://eclipsefp.sourceforge.net/, nevertheless, without any success - after downloading scion I cannot build it cabal install Resolving dependencies... cabal: dependencies conflict: ghc-6.12.3 requires Cabal ==1.8.0.6 however Cabal-1.8.0.6 was excluded because scion-0.1.0.6 requires Cabal ==1.6.* Running Setup.hs through runhaskell seems not to work as well: runhaskell Setup.hs configure Configuring scion-0.1.0.6... Setup.hs: At least the following dependencies are missing: AttoJson =0.5.2, binary ==0.5.*, derive -any, ghc-paths ==0.1.*, ghc-syb -any, ghc-syb-utils -any, hslogger ==1.0.*, list-tries -any, multiset =0.1 0.3, uniplate -any Even if, for instance: cabal info binary * binary (library) Synopsis: Binary serialisation for Haskell values using lazy ByteStrings Latest version available: 0.5.0.2 Latest version installed: 0.5.0.2 Is there any chance to make it install or should I give up? Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Class instances on class constraints
Hello all, For school purposes, I would like to define something like this: module SetOverList( SetFromList , SetOL(..) ) where type SetFromList a = [a] addEq :: Eq a = a - SetFromList a - SetFromList a addEq v [] = [v] addEq v l@(x:xs) = if x==v then l else x : addEq v xs addOrd :: Ord a = a - SetFromList a - SetFromList a addOrd v [] = [v] addOrd v l@(x:xs) = case compare x v of GT - v : l EQ - l LT - x : addOrd v xs class SetOL a where addElem :: a - SetFromList a - SetFromList a instance (Eq a) = SetOL a where addElem = addEq instance (Ord a) = SetOL a where addElem = addOrd which does not work, of course (Flexible or Undecidable instances won't help). The aim is to have addElem function that works differently according to situation whether a type, which is base of the list/set, is a member of class Eq or Ord. Could you point me or hint me how to get as close as possible to the required solution? Maybe I'm not able to see an obvious way... Thanks, Dušan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Class instances on class constraints
Yes! Thanks.
Dušan
On 07/28/2010 01:03 PM, Felipe Lessa wrote:
2010/7/28 Dušan Kolářko...@fit.vutbr.cz:
which does not work, of course (Flexible or Undecidable instances won't
help). The aim is to have addElem function that works differently according
to situation whether a type, which is base of the list/set, is a member of
class Eq or Ord. Could you point me or hint me how to get as close as
possible to the required solution? Maybe I'm not able to see an obvious
way...
Use the good'ol trick:
newtype ByEq a = ByEq {unByEq :: a}
newtype ByOrd a = ByOrd {unByOrd :: a}
instance (Eq a) = SetOL (ByEq a) where
addElem = addEq . unByEq
instance (Ord a) = SetOL (ByOrd a) where
addElem = addOrd . unByOrd
Cheers,
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[Haskell-cafe] Installing wx via cabal
Dear all, Running cabal install --global wx stops very soon with the following error. Building wxcore-0.12.1.2... [ 1 of 22] Compiling Graphics.UI.WXCore.WxcObject ( src/haskell/Graphics/UI/WXCore/WxcObject.hs, dist/build/Graphics/UI/WXCore/WxcObject.o ) [ 2 of 22] Compiling Graphics.UI.WXCore.WxcDefs ( src/haskell/Graphics/UI/WXCore/WxcDefs.hs, dist/build/Graphics/UI/WXCore/WxcDefs.o ) [ 3 of 22] Compiling Graphics.UI.WXCore.WxcClassTypes ( src/haskell/Graphics/UI/WXCore/WxcClassTypes.hs, dist/build/Graphics/UI/WXCore/WxcClassTypes.o ) [ 4 of 22] Compiling Graphics.UI.WXCore.WxcTypes ( src/haskell/Graphics/UI/WXCore/WxcTypes.hs, dist/build/Graphics/UI/WXCore/WxcTypes.o ) [ 5 of 22] Compiling Graphics.UI.WXCore.WxcClassesAL ( src/haskell/Graphics/UI/WXCore/WxcClassesAL.hs, dist/build/Graphics/UI/WXCore/WxcClassesAL.o ) ghc: out of memory (requested 1048576 bytes) cabal: Error: some packages failed to install: It seems quite strange as the machine seems to have 16GB RAM and a free swap, can I somehow put options or so? I have ghc 10.4. installed. Thanks Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] OT: Literature on translation of lambda calculus to combinators
Dear cafe, Could anyone provide a link to some paper/book (electronic version of both preferred, even if not free) that describes an algorithm of translation of untyped lambda calculus expression to a set of combinators? Preferably SKI or BCKW. I'm either feeding google with wrong question or there is no link available now... Thanks, Dušan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Naive booleans and numbers - type-checking fails
Dear cafe, I'm trying to prepare a naive definition of booleans, numbers and some helper functions such a way, so that definition in lambda-calculus can be used in a straightforward way in Haskell. I was caught in trouble quite soon during change of lambda-expressions to Haskell - defining prefn as a helper for prev. When using Haskell-ish if-then-else then there is no problem (the code commented out), while using defined if-then-else (mif), the type-checking fails, but just for this case! Other simple tests are OK for the mif. Do I need some extra option for type-checker, or is it a principal failure (infinite type is reported) - I'm running ghci 6.10.4. mtrue x y = x mfalse x y = y m0 f n = n m1 f n = f n m2 f n = f (f n) msucc x g m = x g (g m) iszero m = m (\_ - mfalse) mtrue mif c t f = c t f mpair f s = \e - e f s mfst p = p mtrue msnd p = p mfalse -- mprefn f p = if mex True False then mth else mel mprefn f p = mif mex mth mel where mex = mfst p mth = mpair mfalse (msnd p) mel = mpair mfalse (f (msnd p)) Please, change of definitions is not a solution, I'm trying to follow available resources, so using something else is not an option. :-( Thanks for any help Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Error during hlint install ?
Yes, it works fine, now. Thank you! Dušan Neil Mitchell wrote: Hi Dusan, Am I doing something wrong if I get the following error during cabal installation of hlint? Is there any way how to solve it? The problem is that version 1.15 of hscolour released recently is incompatible with 1.13 which HLint was being tested against. I've now switched over to hscolour 1.15 and released HLint 1.6.6, which does work with hscolour 1.15. This should solve your problem. I didn't spot this email as I've been busy recently and have not had a chance to read through haskell-cafe, but I did get your personal email (but replied to everyone so that everyone can see the solution). In general when emailing about my packages it's usually best to email haskell-cafe and CC me. Thanks for reporting the issue, and do let me know if the new version still doesn't work. To upgrade you should be able to do: cabal update cabal install hlint Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] OT: Is conference dead?
Hello all, I'm sorry for the OT post, is the conference dead? I've got no mail since yeasterday afternoon. And that is quite unusual. Best regards, Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Threading and Mullticore Computation
Hello, IMO, the conclusion about instant cache misses due to several threads sharing memory and/or performing large memory consumption is very highly probable, especially on Intel CPUs with shared L2 cache. I have several examples, where threading means significant time consumption increase (new time = number of threads * old time). My personal conclusion - use linear recursive functions only (so that they could be optimized), Int instead of Integer, if possible, no data structure traversal (unless such a structure is very small, L2 caches are several MBs only). Such a way cache misses are minimized for both/all threads. Moreover, OS needs some time instantly (= cache refill/misses), thus, I've devoted one core for OS, others for computation (quad core), which brings certain improvement and more accurate measurements. Regards Dusan Bulat Ziganshin wrote: Hello Andrew, Tuesday, March 3, 2009, 9:21:42 PM, you wrote: I just tried it with GHC 6.10.1. Two capabilities is still slower. (See attachments. Compiled with -O2 -threaded.) i don't think so: Total time4.88s ( 5.14s elapsed) Total time7.08s ( 4.69s elapsed) so with 1 thread wall clock time is 5 seconds, with 2 thread wall time is 4.7 seconds cpu time spent increased with 2 threads - this indicates that you either use hyperthreaded/SMT-capable cpu or speed is limited by memory access operations so, my conclusion - this benchmark limited by memory latencies so it cannot be efficiently multithreaded ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Memoization local to a function
Thanks for all the hints and code provided, nevertheless, it implied another questions: 1) Am I right that MemoCombinators can be hardly ever used with hugs? If not, which guidelines to be used for installation... 2) Is there any paper/tutorial/wiki that describes, which local definitions/expressions are discarded/not shared after/to the next computation, that means separated closure is built for them? Dusan Henning Thielemann wrote: On Wed, 25 Feb 2009, Luke Palmer wrote: On Wed, Feb 25, 2009 at 10:38 AM, Dusan Kolar ko...@fit.vutbr.cz wrote: I have a function a computation of which is quite expensive, it is recursively dependent on itself with respect to some other function values - we can roughly model its behaviour with fib function (returns n-th number of Fibonacci's sequence). Unfortunately, it is not fib, it is far more complicated. Nevertheless, for demonstration of my question/problem I will use fib, it's quite good. I suggest using data-memocombinators for this rather than rolling your own. It accomplishes the same thing, but makes the choice of memo structure independent of the code that uses it (and Memo.integral has asymptotically better performance than a list). Nice to know that there is a package for this purpose. See also http://haskell.org/haskellwiki/Memoization -- Dusan Kolartel: +420 54 114 1238 UIFS FIT VUT Brno fax: +420 54 114 1270 Bozetechova 2 e-mail: ko...@fit.vutbr.cz Brno 612 66 Czech Republic -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ByteString.pack behavior
Hello all, Maybe there is something obvious I can't see, but I have this behavior for 6.8.2 ghci: $ghci ttest1p.hs GHCi, version 6.8.2: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. [1 of 1] Compiling Main ( ttest1p.hs, interpreted ) Ok, modules loaded: Main. *Main encode' [1..100] Loading package array-0.1.0.0 ... linking ... done. Loading package bytestring-0.9.0.1 ... linking ... done. [1,0,2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,0,10,0,11,0,12,0,13,0,... // deleted *Main B.pack [0..100] \NUL\SOH\STX\ETX\EOT\ENQ\ACK\a\b\t\n\v\f\r\SO\SI\DLE\DC1\DC2\DC3\DC4\NAK\SYN\ETB\CAN\EM\SUB\ESC\FS\GS\RS\US !\#$%'()*+,-./0123456789:;=[EMAIL PROTECTED] *Main B.pack $ encode' [1..100] *** Exception: divide by zero where ttest1p.hs: import qualified Data.ByteString as B encode' [] = [] encode' (x:xs) = if x==0 then 0:0:encode' xs else (x `mod` 256) : (x `div` 256) : encode' xs What is the difference, except list length and value structure? Where is my error? Thanks for any hint, Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] User data type with operator contructors only
Hello all, my question probably comes from not reading manual properly. But, why is it not possible to have something like: infixr 5 : data Stack a = a : (Stack a) | :|| And if yes, how can I do that? I know that lists are a hack in Haskell, but anyway. Having: infixr 5 : data Stack a = a : (Stack a) | Bottom is not what I would like to have. :-( Thanks for any reference to/or explanation, Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] User data type with operator contructors only
Donald Bruce Stewart wrote: kolar: Hello all, my question probably comes from not reading manual properly. But, why is it not possible to have something like: infixr 5 : data Stack a = a : (Stack a) | :|| And if yes, how can I do that? I know that lists are a hack in Haskell, infixr 5 : data Stack a = a : (Stack a) | (:||) test = 7 : 8 : 2 : (:||) Not ideal, though, I suppose. -- Don Hmm, I see, ghci works, but hugs not. That was my problem. Sorry for asking. I've thought this would work in both. :-( Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] OT - lamba calculus definition - alpha reduction
Hello all, I'm asking in place of several my colleagues and myself of course. The question is almost off topic. It is from lambda calculus definition, in particular, definition of alpha reduction (and others as well). Alpha reduction definition: a lambda expression (\v.e) can be transformed (reduced) to (\v'.e[v'/v]) if the substitution e[v'/v] is valid. Beta reduction definition: a lambda expression (e1 e2) can be reduced to the expression e[e2/v] if e1 is of the form (\v.e) and if the substitution e[e2/v] is valid. Eta reduction definition: a lambda expression e can be reduced to a lambda expression (\v.e v) if v is not free in e. OK. If we have these two expressions: 1) (\x.x b x) 2) (\x.x c x) The question is, are they equal? (They are not identical, of course.) For answer no, there is a strong argument - there is no reduction sequence that can make these identical. On the other hand, their meaning expresses the same operation. Well, what is the answer? I will be lucky with any link to WWW resource or your opinion. Nevertheless, the more formal and precise your answer will be the more I will be lucky. ;-) Thx and regards Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] OT - lamba calculus definition - alpha reduction
I'm asking in place of several my colleagues and myself of course. The question is almost off topic. It is from lambda calculus definition, in particular, definition of alpha reduction (and others as well). Alpha reduction definition: a lambda expression (\v.e) can be transformed (reduced) to (\v'.e[v'/v]) if the substitution e[v'/v] is valid. Beta reduction definition: a lambda expression (e1 e2) can be reduced to the expression e[e2/v] if e1 is of the form (\v.e) and if the substitution e[e2/v] is valid. Eta reduction definition: a lambda expression e can be reduced to a lambda expression (\v.e v) if v is not free in e. OK. If we have these two expressions: 1) (\x.x b x) 2) (\x.x c x) The question is, are they equal? (They are not identical, of course.) For answer no, there is a strong argument - there is no reduction sequence that can make these identical. On the other hand, their meaning expresses the same operation. Well, what is the answer? I will be lucky with any link to WWW resource or your opinion. Nevertheless, the more formal and precise your answer will be the more I will be lucky. ;-) If b and c are free, then no, they can't be considered equal, and i don't see how you can find a common meaning in this case either. Those two are equivalent: (\b.\x.x b x) = (\c.\x.x c x). Yes, those of yours are equal of no doubt. Those of mine are not, that's even my opinion, on the other hand, I was not precise enough in my explanation. Those of mine have the same behavior unless you mean something else by variables b and c. Otherwise the behavior is the same, isn't it? If the behavior is the same, they can be interchanged and, thus, they are equal... OK, I agree this may be a more philosophical question. ;-) Thanks, Dusan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
