Re: [Haskell-cafe] memory-efficient data type for Netflix data - UArray Int Int vs UArray Int Word8
bos: 2009/2/23 Kenneth Hoste kenneth.ho...@ugent.be Does anyone know why the Word8 version is not significantly better in terms of memory usage? Yes, because there's a typo on line 413 of Data/Array/Vector/Prim/BUArr.hs. How's that for service? :-) UArray or UArr? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Pickling a finite map (Binary + zlib) [was: [Haskell-cafe] Data.Binary poor read performance]
wren: Neil Mitchell wrote: 2) The storage for String seems to be raw strings, which is nice. Would I get a substantial speedup by moving to bytestrings instead of strings? If I hashed the strings and stored common ones in a hash table is it likely to be a big win? Bytestrings should help. The big wins in this application are likely to be cache issues, though the improved memory/GC overhead is nice too. Here's a quick demo using Data.Binary directly. First, let's read in the dictionary file, and build a big, worst-case finite map of words to their occurence (always 1). import Data.Binary import Data.List import qualified Data.ByteString.Char8 as B import System.Environment import qualified Data.Map as M main = do [f] - getArgs s - B.readFile f let m = M.fromList [ (head n, length n) | n - (group . B.lines $ s) ] encodeFile dict m print done So that writes a dict file with a binary encoded Map ByteString Int. Using ghc -O2 --make for everying. $ time ./A /usr/share/dict/cracklib-small done ./A /usr/share/dict/cracklib-small 0.28s user 0.03s system 94% cpu 0.331 total Yields a dictionary file Map: $ du -hs dict 1.3Mdict Now, let's read back in and decode it back to a Map main = do [f] - getArgs m - decodeFile f print (M.size (m :: M.Map B.ByteString Int)) print done Easy enough: $ time ./A dict +RTS -K20M 52848 done ./A dict +RTS -K20M 1.51s user 0.06s system 99% cpu 1.582 total Ok. So 1.5s to decode a 1.3M Map. There may be better ways to build the Map since we know the input will be sorted, but the Data.Binary instance can't do that. Since decode/encode are a nice pure function on lazy bytestrings, we can try a trick of compressing/decompressing the dictionary in memory. Compressing the dictionary: import Data.Binary import Data.List import qualified Data.ByteString.Char8 as B import qualified Data.ByteString.Lazy as L import System.Environment import qualified Data.Map as M import Codec.Compression.GZip main = do [f] - getArgs s - B.readFile f let m = M.fromList [ (head n, length n) | n - (group . B.lines $ s) ] L.writeFile dict.gz . compress . encode $ m print done Pretty cool, imo, is compress . encode: $ time ./A /usr/share/dict/cracklib-small done ./A /usr/share/dict/cracklib-small 0.38s user 0.02s system 85% cpu 0.470 total Ok. So building a compressed dictionary takes only a bit longer than uncompressed one (zlib is fast), $ du -hs dict.gz 216Kdict.gz Compressed dictionary is much smaller. Let's load it back in and unpickle it: main = do [f] - getArgs m - (decode . decompress) `fmap` L.readFile f print (M.size (m :: M.Map B.ByteString Int)) print done Also cute. But how does it run: $ time ./A dict.gz 52848 done ./A dict.gz 0.28s user 0.03s system 98% cpu 0.310 total Interesting. So extracting the Map from a compressed bytestring in memory is a fair bit faster than loading it directly, uncompressed from disk. Neil, does that give you some ballpark figures to work with? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The community is more important than the product
http://haskell.org/haskellwiki/Protect_the_community Random notes on how to maintain tone, focus and productivity in an online community I took a few years ago. Might be some material there if anyone's seeking to help ensure we remain a constructive, effective community. -- Don P.S. release some code on hackage.haskell.org. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Template Haskell compilation error on Windows (was Re: speed: ghc vs gcc)
Missing --make bugfact: I tried to compile the template Haskell loop unrolling trick from Claus Reinke on my machine which is running Windows and GHC 6.10.1, and I got linker errors. c:\tempghc -O2 -fvia-C -optc-O3 -fforce-recomp Apply.hs Apply.o:ghc6140_0.hc:(.text+0x7d): undefined reference to ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: speed: ghc vs gcc
Bulat, you've some serious lessons to learn on how to interact with online communities. First, 1. Stop posting replies to every post on this thread 2. Read some of the fine literature on how to be a productive, contributing member of a mailing list community, http://haskell.org/haskellwiki/Protect_the_community 3. Then see if you can rephrase your concerns in a form that will be useful. Claus (as always) has made a fine suggestion: http://www.haskell.org/pipermail/haskell-cafe/2009-February/056241.html 3. Come back with some analysis, or a ticket, and authentically try to collaborate with people here to improve or fix the problems you see. I'm setting your moderation bit now, and in public so we all know what is going on, so your posts will bounce until you do something constructive. This will likely expire in a few days - just enough to calm things down. -- Don (on jerk police protrol today) P.S. if anyone strongly objects, let's talk offline how better to manage things. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] ANNOUNCE: X Haskell Bindings 0.2
aslatter: I'd like to announce the 0.2.* series release of the X Haskell Bindings. This release, like the prior 0.1.* series focuses on making the API prettier. This does mean that there's a good chance this is a breaking release. Also, 0.2.* is based on the just-released version 1.4 of the XML descriptions of the X protocol. The goal of XHB is to provide a Haskell implementation of the X11 wire protocol, similar in spirit to the X protocol C-language Binding (XCB). On Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xhb Woo, well done! Here's an Arch Linux package, http://aur.archlinux.org/packages.php?ID=23765 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] speed: ghc vs gcc
bulat.ziganshin:
Hello haskell-cafe,
since there are no objective tests comparing ghc to gcc, i made my own
one. these are 3 programs, calculating sum in c++ and haskell:
Wonderful. Thank you!
main = print $ sum[1..10^9::Int]
This won't be comparable to your loop below, as 'sum' is a left fold
(which doesn't fuse under build/foldr).
You should use the list implementation from the stream-fusion package (or
uvector) if you're expecting it to fuse to the following loop:
main = print $ sum0 (10^9) 0
sum0 :: Int - Int - Int
sum0 0 !acc = acc
sum0 !x !acc = sum0 (x-1) (acc+x)
Note the bang patterns aren't required here. It compiles to the
following core:
$wsum0 :: Int# - Int# - Int#
$wsum0 =
\ (ww_sON :: Int#) (ww1_sOR :: Int#) -
case ww_sON of ds_XD0 {
_ - $wsum0 (-# ds_XD0 1) (+# ww1_sOR ds_XD0);
0 - ww1_sOR
which is perfect.
Main_zdwsum0_info:
testq %rsi, %rsi
movq%rsi, %rax
jne .L2
movq%rdi, %rbx
jmp *(%rbp)
.L2:
leaq-1(%rsi), %rsi
addq%rax, %rdi
jmp Main_zdwsum0_info
Which seems ... OK.
$ ghc-core A.hs -fvia-C -optc-O3
$ time ./A
55
./A 1.12s user 0.00s system 99% cpu 1.127 total
Works for me. That's on linux x86_64, gcc 4.4
Trying -fasm:
Main_zdwsum0_info:
.LcQs:
movq %rsi,%rax
testq %rax,%rax
jne .LcQw
movq %rdi,%rbx
jmp *(%rbp)
.LcQw:
movq %rdi,%rcx
addq %rax,%rcx
leaq -1(%rax),%rsi
movq %rcx,%rdi
jmp Main_zdwsum0_info
$ time ./A
55
./A 1.65s user 0.00s system 98% cpu 1.677 total
Is a bit slower.
main()
{
int sum=0;
//for(int j=0; j100;j++)
for(int i=0; i1000*1000*1000;i++)
sum += i;
return sum;
}
Well, that's a bit different. It doesn't print the result, and it returns a
different
results on 64 bit
$ gcc -O0 t.c
$ time ./a.out
-1243309312
./a.out 3.99s user 0.00s system 88% cpu 4.500 total
$ gcc -O1 t.c
$ time ./a.out
-1243309312
./a.out 0.88s user 0.00s system 99% cpu 0.892 total
$ gcc -O3 -funroll-loops t.c
$ time ./a.out
-1243309312
./a.out 0.31s user 0.00s system 97% cpu 0.318 total
I don't get anything near the 0.062s which is interesting.
The print statement slows things down, I guess...
So we have:
ghc -fvia-C -O2 1.127
ghc -fasm 1.677
gcc -O0 4.500
gcc -O3 -funroll-loops 0.318
So. some lessons. GHC is around 3-4x slower on this tight loop. (Which isn't as
bad as it used to be).
That's actually a worse margin than any current shootout program, where we are
no
worse than 2.9 slower on larger things:
http://shootout.alioth.debian.org/u64q/benchmark.php?test=alllang=ghclang2=gccbox=1
execution times:
sum:
ghc 6.6.1 -O2 : 12.433 secs
ghc 6.10.1 -O2 : 12.792 secs
sum-fast:
ghc 6.6.1 -O2 : 1.919 secs
ghc 6.10.1 -O2 : 1.856 secs
ghc 6.10.1 -O2 -fvia-C : 1.966 secs
C++:
gcc 3.4.5 -O3 -funroll-loops: 0.062 secs
I couldn't reproduce your final number.
Now, given GHC gets most of the way there -- I think this might make a good bug
report against GHC head, so we can see if the new register allocator helps any.
http://hackage.haskell.org/trac/ghc/newticket?type=bug
Thanks for the report, Bulat!
-- Don
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Re: [Haskell-cafe] speed: ghc vs gcc
bulat.ziganshin: Friday, February 20, 2009, 7:41:33 PM, you wrote: main = print $ sum[1..10^9::Int] This won't be comparable to your loop below, as 'sum' is a left fold (which doesn't fuse under build/foldr). You should use the list implementation from the stream-fusion package (or uvector) if you're expecting it to fuse to the following loop: it was comparison of native haskell, low-level haskell (which is harder to write than native C) and native C. stream-fusion and any other packages provides libraries for some tasks but they can't make faster maps, for example. so i used plain list Hmm? Maybe you're not familiar with the state of the art? $ cabal install uvector Write a loop at a high level: import Data.Array.Vector main = print (sumU (enumFromToU 1 (10^9 :: Int))) Compile it: $ ghc-core A.hs -O2 -fvia-C -optc-O3 Yielding: s16h_info: cmpq6(%rbx), %rdi jg .L2 addq%rdi, %rsi leaq1(%rdi), %rdi jmp s16h_info Running: $ time ./A 55 ./A 0.97s user 0.01s system 99% cpu 0.982 total Now, (trying to avoid the baiting...) this is actually *very* interesting. Why is this faster than the manual recursion we did earlier why do we get better assembly? Again, if you stick to specifics, there's some interesting things we can learn here. Which seems ... OK. really? :D No, see above. I don't get anything near the 0.062s which is interesting. it was beautiful gcc optimization - it added 8 values at once. with xor results are: xor.hs 12.605 xor-fast.hs 1.856 xor.cpp 0.339 GCC is a good loop optimiser. But apparently not my GCC. So we have: ghc -fvia-C -O2 1.127 ghc -fasm 1.677 gcc -O0 4.500 gcc -O3 -funroll-loops 0.318 why not compare to ghc -O0? also you can disable loop unrolling in gcc and unroll loops manually in haskell. or you can generate asm code on the fly. there are plenty of tricks to prove that gcc generates bad code :D No, we want to show (I imagine) that GHC is within a factor or two of C. I usually set my benchmark to beat gcc -O0 fwiw, and then to hope to be within 2x of optimised C. I'm not sure what you're standards are. So. some lessons. GHC is around 3-4x slower on this tight loop. (Which isn't as bad as it used to be). really? what i see: low-level haskell code is usually 3 times harder to write and 3 times slower than gcc code. native haskell code is tens to thousands times slower than C code (just recall that real programs use type classes and monads in addition to laziness) thousands times, now you're just undermining your own credibility here. Stick to what you can measure. If anything we'd expect GCC's magic loop skillz to be less useful on large code bases. That's actually a worse margin than any current shootout program, where we are no worse than 2.9 slower on larger things: 1) most benchmarks there depend on libraries speed. in one test, for example, php is winner 2) for the sum program ghc libs was modified to win in benchmark It is interesting that the 2.9x slower in the shootout is pretty much what we found in this benchmark too. 3) the remaining 1 or 2 programs that measure speed of ghc-generated code was hardly optimized using low-level code, so they don't have anything common with real haskell code most of us write every day Depends on where you work. Now, given GHC gets most of the way there -- I think this might make a good bug report against GHC head, so we can see if the new register allocator helps any. you mean that 6.11 includes new allocator? in that case you can test it too Yes. http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/IntegratedCodeGen i believe that ghc developers are able to test sum performance without my bugreports :D No! This is not how open source works! You *should submit bug reports* and *analysis*. It is so so much more useful than complaining and throwing stones. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: speed: ghc vs gcc
barsoap:
Don Stewart d...@galois.com wrote:
No! This is not how open source works! You *should submit bug
reports* and *analysis*. It is so so much more useful than
complaining and throwing stones.
Exactly. I don't know where, but I read that the vast majorities of
Linux bugs are reported, nailed, and then fixed, by at least three
different persons: The first reports a misbehaviour, the second manages
to find it surfacing in a certain line of code, the third instantly
knows how to make it go away.
Elaboarting further:
Thinking more about Bulat's code gen observations, I think there's something
wrong here -- other than that GHC needs the new codegen to do any of the
fancier loop optimisations.
If we take what I usually see as the best loops GHC can do for this kind of
thing:
import Data.Array.Vector
main = print (sumU (enumFromToU 1 (10^9 :: Int)))
And compile it:
$ ghc-core A.hs -O2 -fvia-C -optc-O3
We get ideal core, all data structures fused away, and no heap allocation:
$wfold_s15t :: Int# - Int# - Int#
$wfold_s15t =
\ (ww1_s150 :: Int#) (ww2_s154 :: Int#) -
case # ww2_s154 ww_s14U of wild_aWm {
False -
$wfold_s15t
(+# ww1_s150 ww2_s154) (+# ww2_s154 1);
True - ww1_s150
}; } in
case $wfold_s15t 0 1
Which produces nice assembly:
s16e_info:
cmpq6(%rbx), %rdi
jg .L2
addq%rdi, %rsi
leaq1(%rdi), %rdi
jmp s16e_info
This is the best GHC will do here, in my experience, and I'm satisifed with it.
Short of new backend tweaks, and realising that GHC is not the loop magic
compiler GCC is.
http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/IntegratedCodeGen
We can be happy with this. The compiler is doing exactly what we expect.
$ time ./B
55
./B 0.96s user 0.00s system 99% cpu 0.967 total
Now, going back to the low level version, Bulat's loop:
main()
{
int sum=0;
//for(int j=0; j100;j++)
for(int i=0; i1000*1000*1000;i++)
sum += i;
return sum;
}
What was first confusing for me was that he wrote the loop backwards when
translating to Haskell,
like this:
main = print $ sum0 (10^9) 0
sum0 :: Int - Int - Int
sum0 0 !acc = acc
sum0 !x !acc = sum0 (x-1) (acc+x)
(The bang patterns aren't needed). Note how he counts backwards from 10^9. Was
there a reason for that, Bulat?
I wondered if we just got worse code on backwards counting loops. So
translating into the obvious translation, counting up:
main = print (sum0 0 1)
sum0 :: Int - Int - Int
sum0 acc n | n 10^9 = acc
| otherwise = sum0 (acc + n) (n + 1)
Which I actually consider to be the same difficulty as writing the C version,
fwiw...
We start to notice something interesting:
$wsum0 :: Int# - Int# - Int#
$wsum0 =
\ (ww_sOH :: Int#) (ww1_sOL :: Int#) -
case lvl2 of wild1_aHn { I# y_aHp -
case # ww1_sOL y_aHp of wild_B1 {
False -
letrec {
$wsum01_XPd :: Int# - Int# - Int#
$wsum01_XPd =
\ (ww2_XP4 :: Int#) (ww3_XP9 :: Int#) -
case # ww3_XP9 y_aHp of wild11_Xs {
False -
$wsum01_XPd (+# ww2_XP4 ww3_XP9) (+# ww3_XP9 1);
True - ww2_XP4
}; } in
$wsum01_XPd (+# ww_sOH ww1_sOL) (+# ww1_sOL 1);
True - ww_sOH
}
Why is there an extra test? What is GHC doing?
Checking the asm:
$ ghc -O2 -fasm
sQ3_info:
.LcRt:
cmpq 8(%rbp),%rsi
jg .LcRw
leaq 1(%rsi),%rax
addq %rsi,%rbx
movq %rax,%rsi
jmp sQ3_info
$ time ./B
55
./B 1.30s user 0.01s system 98% cpu 1.328 total
So its a fair bit slower. Now, we should, as a principle, be able to write sum
directly as I did , and get the
same code from the manual, and automatically , fused version. But we didn't.
Checking via C:
$ ghc -O2 -optc-O3 -fvia-C
Better code, but still a bit slower:
sQ3_info:
cmpq8(%rbp), %rsi
jg .L8
addq%rsi, %rbx
leaq1(%rsi), %rsi
jmp sQ3_info
Running:
$ time ./B
55
./B 1.01s user 0.01s system 97% cpu 1.035 total
So I think we have a bug report! Why did GHC put that extra test in place?
Now, none of this addresses (I think) Bulat's point that GCC can unroll loops
and do other loop magic.
That's handled under a different workflow - the new code generator.
I'll create the ticket.
-- Don
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Re: [Haskell-cafe] Re: speed: ghc vs gcc
claus.reinke:
Concrete examples always help, thanks.
In simple enough situations, one can roll one's own loop unrolling;),
somewhat like shown below (worker/wrapper split to bring the function
parameter representing the loop body into scope, then template haskell
to unroll its applications syntactically, then optimization by
transformation
to get rid of the extra code). It is all rather more complicated than one
would like it to be, what with TH scoping restrictions and all, but
perhaps a library of self-unrolling loop combinators along these lines
might help, as a workaround until ghc does its own unrolling.
Claus
{-# LANGUAGE TemplateHaskell #-}
module Apply where
import Language.Haskell.TH.Syntax
apply i bound | ibound = [| \f x - $(apply (i+1) bound) f (f i x) |]
| otherwise = [| \f x - x |]
{-# LANGUAGE CPP #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -DN=8 -ddump-splices #-}
module Main(main) where
import Apply
main = print $ loopW 1 (10^9) body 0
{-# INLINE loopW #-}
loopW :: Int - Int - (Int - Int - Int) - Int - Int
loopW i max body acc = loop i acc
where
loop :: Int - Int - Int
loop !i !acc | i+N=max = loop (i+N) ($(apply (0::Int) N) (\j acc-body
(i+j) acc) acc)
{-
loop !i !acc | i+8=max = loop (i+8) ( body (i+7)
$ body (i+6)
$ body (i+5)
$ body (i+4)
$ body (i+3)
$ body (i+2)
$ body (i+1)
$ body i acc)
-}
loop !i !acc | i=max= loop (i+1) (body i acc)
| otherwise = acc
body :: Int - Int - Int
body !i !acc = i+acc
Great thinking! This is EXTREMELY COOL!
Main.hs:15:42-57: Splicing expression
let
apply = apply
$dOrd = GHC.Base.$f1
$dNum = GHC.Num.$f6
$dLift = Language.Haskell.TH.Syntax.$f18
in apply (0 :: Int) 8
==
\ f[a1KU] x[a1KV]
- \ f[a1KW] x[a1KX]
- \ f[a1KY] x[a1KZ]
- \ f[a1L0] x[a1L1]
- \ f[a1L2] x[a1L3]
- \ f[a1L4] x[a1L5]
- \ f[a1L6] x[a1L7]
- \ f[a1L8] x[a1L9]
- \ f[a1La]
x[a1Lb] - x[a1Lb]
f[a1L8]
(f[a1L8] 7 x[a1L9])
f[a1L6] (f[a1L6]
6 x[a1L7])
f[a1L4] (f[a1L4] 5
x[a1L5])
f[a1L2] (f[a1L2] 4 x[a1L3])
f[a1L0] (f[a1L0] 3 x[a1L1])
f[a1KY] (f[a1KY] 2 x[a1KZ])
f[a1KW] (f[a1KW] 1 x[a1KX])
f[a1KU] (f[a1KU] 0 x[a1KV])
In the second argument of `loop', namely
`($(apply (0 :: Int) 8) (\ j acc - body (i + j) acc) acc)'
In the expression:
loop
(i + 8) ($(apply (0 :: Int) 8) (\ j acc - body (i + j) acc) acc)
In the definition of `loop':
loop !i !acc
| i + 8 = max
= loop
(i + 8) ($(apply (0 :: Int) 8) (\ j acc - body (i + j)
acc) acc)
So, that's the fastest yet:
$ time ./Main
55
./Main 0.61s user 0.00s system 98% cpu 0.623 total
And within 2x the best GCC was doing,
gcc -O3 -funroll-loops 0.318
If we unroll even further...
$ ghc -O2 -fvia-C -optc-O3 -D64 Main.hs
$ time ./Main
55
./Main 0.08s user 0.00s system 94% cpu 0.088 total
Very very nice, Claus!
Now I'm wondering if we can do this via rewrite rules
-- Don
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Re: [Haskell-cafe] Re: speed: ghc vs gcc
bulat.ziganshin: Hello Achim, Friday, February 20, 2009, 11:44:49 PM, you wrote: Turning this into a ticket with associated test will: but why you think that this is untypical and needs a ticket? ;) Bulat, you are right in every aspect. You never did anything wrong. Achim, this is simplest code one can imagine. so when Simon will go to check ghc optimizations, he will try it without any reports. but Simon, unlike Don, never said that ghc may be compared to gcc. Don, on the other hand, say this everyday. when he is asked for code that shows this, he declined to answer. so - why YOU think that ghc generates fast code and this example is something unusual? can you provide any *technical* arguments or will continue to make personal attacks together with Don? Bulat, you misunderstand, it is not personal! We just want something to work on. Something specific. For example, you've identified loop unrolling as something that could very profitably be improved in GHC, and Claus even wrote a prototype to see what kind of speedups to guess. This is a great contribution! Now we know where to hunt. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: speed: ghc vs gcc
dons: bulat.ziganshin: Hello Achim, Friday, February 20, 2009, 11:44:49 PM, you wrote: Turning this into a ticket with associated test will: but why you think that this is untypical and needs a ticket? ;) Bulat, you are right in every aspect. You never did anything wrong. Achim, this is simplest code one can imagine. so when Simon will go to check ghc optimizations, he will try it without any reports. but Simon, unlike Don, never said that ghc may be compared to gcc. Don, on the other hand, say this everyday. when he is asked for code that shows this, he declined to answer. so - why YOU think that ghc generates fast code and this example is something unusual? can you provide any *technical* arguments or will continue to make personal attacks together with Don? Bulat, you misunderstand, it is not personal! We just want something to work on. Something specific. For example, you've identified loop unrolling as something that could very profitably be improved in GHC, and Claus even wrote a prototype to see what kind of speedups to guess. This is a great contribution! Now we know where to hunt. And just to summarise what we have seen: ghc -O2 naive left fold15.680 gcc -O0 4.500 ghc manual recursion -fasm 1.328 ghc manual recursion1.035 ghc naive left fold stream fusion 0.967 gcc -O1 0.892 ghc -funroll-loops -D80.623 gcc -O3 -funroll-loops 0.318 ghc -funroll-loops -D64 0.088 So what did we learn here? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: speed: ghc vs gcc
bulat.ziganshin: Hello Achim, Saturday, February 21, 2009, 1:17:08 AM, you wrote: nothing new: what you are not interested in real compilers comparison, preferring to demonstrate artificial results ...that we have a path to get better results than gcc -O3 -funroll-loops, and it's within reach... we even can get there now, albeit not in the most hack-free way imaginable? well, can this be made for C++? yes. moreover, gcc does this trick *automatically*, while with ghc we need to write 50-line program using Template Haskell and then run it through gcc - and finally get exactly the same optimization we got automatic for C code so, again: this confirms that Don is always build artificial comparisons, optimizing Haskell code by hand and ignoring obvious ways to optimize Haskell code. unfortunately, this doesn't work in real live. and even worse - Don reports this as fair Haskell vs C++ comparison This is extremely depressing to read after the good results and lessons of this thread. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] speed: ghc vs gcc vs jhc
bulat.ziganshin: Hello John, Saturday, February 21, 2009, 3:42:24 AM, you wrote: this is true for *application* code, but for codec you may have lots of code that just compute, compute, compute Yes indeed. If there is code like this out there for haskell, I would love to add it as a test case for jhc. Crypto library has a lot of native haskell code computing hashes and encrypting data hopefully people will show other examples btw, Galois Cryptol has haskell backend, are you know? with jhс compilation it can probably generate as fast code as C backend does. it will be very interesting for us and even look as something close to production usage. i have crossposted message to Don That's a very interesting idea. The output from Cryptol is self contained enough, and simple, numerical code, that JHC probably could handle it -- it doesn't require extensive libraries or runtime support, for example. This warrents investigation. Thanks for the suggestion! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: speed: ghc vs gcc
bertram.felgenhauer: This is odd, but it doesn't hurt the inner loop, which only involves $wsum01_XPd, and is identical to $wfold_s15t above. Checking the asm: $ ghc -O2 -fasm sQ3_info: .LcRt: cmpq 8(%rbp),%rsi jg .LcRw leaq 1(%rsi),%rax addq %rsi,%rbx movq %rax,%rsi jmp sQ3_info So for some reason ghc ends up doing the (n + 1) addition before the (acc + n) addition in this case - this accounts for the extra instruction, because both n+1 and n need to be kept around for the duration of the addq (which does the acc + n addition). Yep, well spotted. Checking via C: $ ghc -O2 -optc-O3 -fvia-C Better code, but still a bit slower: sQ3_info: cmpq8(%rbp), %rsi jg .L8 addq%rsi, %rbx leaq1(%rsi), %rsi jmp sQ3_info This code is identical (up to renaming registers and one offset that I can't fully explain, but is probably related to a slight difference in handling pointer tags between the two versions of the code) to the nice assembly above. Indeed, which is gratifying. Running: $ time ./B 55 ./B 1.01s user 0.01s system 97% cpu 1.035 total Hmm, about 5% slower, are you sure this isn't just noise? If not noise, it may be some alignment effect. Hard to say. I couldn't get it under 1s from a dozen runs, so assuming some small effect with alignment. Why we get the extra test in the outer loop though, not sure. That's new too I think -- at least I've not seen that pattern before. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: garbage collector woes
waterson: On Feb 17, 2009, at 12:22 PM, Chris Waterson wrote: I'm at wits end with respect to GHC's garbage collector and would very much appreciate a code review of my MySQL driver for HDBC, which is here: http://www.maubi.net/~waterson/REPO/HDBC-mysql/Database/HDBC/MySQL/Connection.hsc In particular, the problem that I'm having is that my statements (really, just iterators over a SQL query result set) are getting garbage collected prematurely. So (*blush*), my woes turned out to be my misunderstanding of the MySQL C API, which I have now come to terms with. I apologize for the noise here. Is the solution written up somewhere so we can point to that next time? :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to create an online poll
This looks very promising! Investigating... anton: There's also the Condorcet Internet Voting Service: http://www.cs.cornell.edu/andru/civs.html gregg reynolds wrote: See also www.surveymonkey.com Bulat Ziganshin bulat.zigans...@gmail.com wrote: Hello haskell-cafe, http://zohopolls.com/ ___ 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] Polymorphism overhead
wasserman.louis: I have (roughly) the following code: data Foo e type MFoo e = Maybe (Foo e) instance Ord e = Monoid (Foo e) where f1 `mappend` f2 = code invoking the mappend instance from Maybe (Foo e) I'd expect this to optimize to the same thing as if I had implemented: meld :: Ord e = Foo e - Foo e - Foo e f1 `meld` f2 = -- code invoking meld' meld' :: Ord e = Maybe (Foo e) - Maybe (Foo e) - Maybe (Foo e) meld' (Just f1) (Just f2) = meld f1 f2 meld' m1 Nothing = m1 meld' Nothing m2 = m2 instance Ord e = Monoid (Foo e) where mappend = meld However, GHC's Core output tells me that the first piece of code reexamines the polymorphism in every recursion, so that mappend, which is used in the Monoid instance of Foo, looks up the Monoid instance of Foo again (for the sole purpose of looking itself up) and recurses with that. Why is this, and is there a way to fix that? In general, INLINE or SPECIALIZE -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Arch Haskell News: Feb 16 2009
Arch now has 926 Haskell packages in AUR. That’s an increase of 27 new packages in the last 8 days, or 3.38 new Haskell apps a day. This weekly news includes: * Noteworthy updates: grapefruit, haskelldb, gtk2hs * A video on how to use Arch packages * Updated releases by category Read it all: http://archhaskell.wordpress.com/2009/02/16/arch-haskell-news-feb-16-2009/ Enjoy! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN : Crypto 4.2.0 Related News
wchogg: Hello Haskellers, I'm pleased to announce version 4.2.0 of Crypto has been uploaded to Hackage that I am taking over maintenance of the library from Dominic Steinitz. As of this release it should be cabal install'able on GHC 6.10.1. I'm also pleased to announce that the darcs repo will be moving from code.haskell.org to being hosted on Patch-Tag at http://patch-tag.com/repo/crypto/home. You don't need to sign up for Patch-Tag to use the read only repos, but you will need an account if you want to be given write access to the crypto repository. Please feel free to e-mail me with any issues or questions. Great! Good to see the torch passed on. Packaged up for Arch, http://aur.archlinux.org/packages.php?ID=17492 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Memory
inbuninbu: Hello All, The kind people at #haskell suggested I come to haskell-cafe for questions about haskell performance issues. I'm new to haskell, and I'm having a hard time understanding how to deal with memory leaks. I've been playing with some network server examples and I noticed with each new connection, the memory footprint increases by about 7k However, the leaks don't seem to have anything to do with the networking code. Actually I get a huge leak just from using using 'forever'. import Control.Monad import System.IO main = forever $ putStrLn hi When I run it for a few seconds with profiling... total time =0.36 secs (18 ticks @ 20 ms) total alloc = 54,423,396 bytes (excludes profiling overheads) Can this be right? did you compile with optimisations on? $ ghc -O2 A.hs --make $ time ./A +RTS -sstderr 17,880 bytes maximum residency (1 sample(s)) 18,984 bytes maximum slop 1 MB total memory in use (0 MB lost due to fragmentation) Generation 0: 9951 collections, 0 parallel, 0.07s, 0.07s elapsed Generation 1: 1 collections, 0 parallel, 0.00s, 0.00s elapsed INIT time0.00s ( 0.00s elapsed) MUT time4.45s ( 16.08s elapsed) GCtime0.07s ( 0.07s elapsed) EXIT time0.00s ( 0.00s elapsed) Total time4.52s ( 16.16s elapsed) %GC time 1.5% (0.5% elapsed) Alloc rate1,173,414,505 bytes per MUT second Productivity 98.5% of total user, 27.5% of total elapsed ./A +RTS -sstderr 4.52s user 10.61s system 93% cpu 16.161 total So it's allocating small cells, frequently, then discarding them -- and running in constant space. Looking further, forever :: (Monad m) = m a - m b forever a = a forever a Well, here, the result is thrown away anyway. And the result is (), so I'd expect constant space. Looks good to me. Did you run it without optimisations, on , perhaps? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Epic failure
OK, what did I do wrong here?
When making a request for help on a compiler issue, you failed to include key
information to make it possible to reproduce your problem, and what you did
include was broken or incorrect.
The three programs that submitted don't do even do the same thing.
Let's look into this further.
* Program 1:
module Main () where
import Data.List
top = 10 ^ 8 :: Int
main = do
let numbers = [1 .. top]
print $ foldl' (+) 0 numbers
-- Runtime is 20 seconds.
Well, let's see if we can reproduce this:
$ ghc -O2 A.hs --make
[1 of 1] Compiling Main ( A.hs, A.o )
Linking A ...
$ time ./A
50005000
./A 1.54s user 0.01s system 98% cpu 1.571 total
Nope. OK, so this seems like user error. Without more info about how you
conducted your experiment, the results are meaningless.
My guess is that you compiled it without optimisations?
Nope, not that,
$ ghc -O0 --make A.hs
$ time ./A
50005000
./A 2.65s user 0.01s system 99% cpu 2.667 tota
So even with all optimisations disabled, it is still an order of magnitude
faster than the number you presented. Resolution: invalid. Not reproducible.
* Program 2
#include stdio.h
int main(void)
{
int total = 0;
int n;
for (n = 1, n 1; n++)
total += n;
printf(%d, n);
}
// Runtime is 0.8 seconds.
Ok. Let's try this then, a C program:
$ gcc t.c
t.c: In function ‘main’:
t.c:8: error: expected ‘;’ before ‘)’ token
Ah, an incorrect C program. Correcting the OP's typo:
$ time ./a.out
1
./a.out 0.41s user 0.00s system 100% cpu 0.416 total
So its actually a different program. Is this supposed to print 'total'?
This program seems wrong in a number of other ways too.
Resolution: non-sequitor
Program 3
module Main () where
import Data.List
top = 10 ^ 8 :: Int
kernel i o = if i top then o `seq` kernel (i+1) (o+i) else o
main = do
print $ kernel 1 0
-- Runtime is 0.5 seconds.
Clearly these two nearly identical Haskell programs should have exactly
the same runtime. Instead, one is 40x slower. Clearly something has gone
catastrophically wrong here. The whole point of GHC's extensive optimiser
passes are to turn the first example into the second example - but
something somewhere hasn't worked. Any suggestions?
Ok, another program. Let's try this.
$ ghc -O2 B.hs --make
[1 of 1] Compiling Main ( B.hs, B.o )
Linking B ...
$ time ./B
49995000
./B 0.18s user 0.00s system 98% cpu 0.186 total
Oh, this is produces yet another result. In 0.186 seconds.
So, going back to the original question, what did you do wrong?
If you're seeking input for a technical error relating to performance, you
should have, but failed to:
* Use programs that implement the same algorithm
* Indicate which compiler versions/optimisations/architecture you're on
* State what you expected the results to be.
Besides the technical aspects, your presentation categorises the post somwhere
between internet
crank and internet troll, as:
* You used an inflammatory title, which doesn't inspire trust.
* You jumped to conclusions on the fundamental nature of a technology,
striking at its reasons for existing, without considering to recheck your
assumptions.
So yes, epic fail. And after three years of this, I'm not hopeful.
But perhaps you can take some lessons from this post to improve your next one?
Now, assuming good faith, and you were just very confused about what you were
measuring, or how to measure it, or how to ask for help in a technical forum,
here's some more fun: let's write your 1st program, and see if GHC can
transform it into your 3rd program.
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.10.1
$ uname -msr
Linux 2.6.28-ARCH x86_64
$ gcc --version
gcc (GCC) 4.3.3
$ ghc-pkg list uvector
uvector-0.1.0.3
Here's a a program written with combinators in a high level style (and using a
library written in a high level way):
import Data.Array.Vector
main = print . sumU . enumFromToU 0 $ (10^8 :: Int)
Compiling it,
$ ghc -O2 --make C.hs
Which yields the following core,
$wfold_s15D :: Int# - Int# - Int#
$wfold_s15D =
\ (ww1_s15a :: Int#) (ww2_s15e :: Int#) -
case # ww2_s15e ww_s154 of wild_a12I {
False -
$wfold_s15D
(+# ww1_s15a ww2_s15e) (+# ww2_s15e 1);
True - ww1_s15a
Because GHC knows how to optimise loops of these forms.
And the resulting assembly is pretty nice,
s16o_info:
.Lc17g:
cmpq 6(%rbx),%rdi
jg
Re: [Haskell-cafe] HaskellDB is alive?
felipe.lessa: Hello! There was a new HaskellDB release, but I didn't see any announcement here. Is it back alive? What happened to 0.11? Thanks =) http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskelldb-0.12 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Graph library, was: Haskell.org GSoC
g9ks157k: Am Samstag, 14. Februar 2009 16:59 schrieb Brent Yorgey: On Thu, Feb 12, 2009 at 04:10:21PM +0100, Wolfgang Jeltsch wrote: Am Donnerstag, 12. Februar 2009 15:34 schrieb Thomas DuBuisson: Get a community.haskell.org account once you are ready to start a repo, it can not only host your repo (ex: http://community.haskell.org/~tommd/pureMD5) but also allows you to upload packages to hackage.haskell.org. I already have a Hackage account. Can this be readily used as a community.haskell.org account? If not, what if I get a community account. Do I have two accounts for Hackage access then? No, they are two separate things. A Hackage account just lets you upload things to Hackage. A community.haskell.org account lets you log into code.haskell.org (a completely different server than Hackage), host projects there, and so on. But Thomas DuBuisson wrote that you can upload packages to HackageDB with your community.haskell.org account (see above). Is this wrong? Yes. Register for community accounts (shell, trac, darcs etc) http://community.haskell.org/ (or you can use github if all you need is a repo). To get hackage upload perms, http://hackage.haskell.org/packages/accounts.html -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: haha-0.1 - Animated ascii lambda
sfvisser: Always wanted to have an full-color rotating vector based ascii art lambda on your terminal? This is your chance, installing `haha' will do the trick! This is very minimal vector based ascii art library written just for fun. There is a sample program called `rotating-lambda' which does exactly what is says. Make sure your terminal window is at least 80x40 and supports the most basic ANSI escape sequences before trying the demo. Very smoothly done! Here's a video of what he's talking about, http://www.youtube.com/watch?v=MugQXHUZPK8 Raw video, http://galois.com/~dons/images/rotating-lambda.ogv -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell.org GSoC
g9ks157k: Am Mittwoch, 11. Februar 2009 18:51 schrieb Don Stewart: For example, if all the haddocks on hackage.org were a wiki, and interlinked, every single package author would benefit, as would all users. You mean, everyone should be able to mess about with my documentation? This would be similar to give everyone commit rights to my repositories or allow everyone to edit the code of my published libraries. What is the good thing about that? No one said anything about unrestricted commit rights ... we're not crazy ... what if it were more like, say, RWH's wiki .. where comments go to editors to encorporate ... -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
Malcolm.Wallace: Gwern Branwen gwe...@gmail.com wrote: * A GUI interface to Darcs (http://hackage.haskell.org/trac/summer-of-code/ticket/17); I wonder whether darcs ought to apply to be a GSoC mentoring organisation in its own right this year? It would be good to attempt to get a couple of dedicated slots for darcs only (in addition to any that haskell.org may get). * Optimization of containers (http://hackage.haskell.org/trac/summer-of-code/ticket/1549). Would benefit every Haskell user very quickly. This was Jamie Brandon's GSoC project last year, and although that is not yet in wide use, I suspect there is very little extra effort needed to get it out there into the average Haskell user's hands. * XMonad compositing support (http://hackage.haskell.org/trac/summer-of-code/ticket/1548). Maybe XMonad should also think about whether to apply to GSoC in their own right as a mentoring org? As a project, it seems to have a lot of life independent of the Haskell community. I agree: the big projects can stand on their own. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
gtener: On Thu, Feb 12, 2009 at 11:36, Malcolm Wallace malcolm.wall...@cs.york.ac.uk wrote: Gwern Branwen gwe...@gmail.com wrote: * A GUI interface to Darcs (http://hackage.haskell.org/trac/summer-of-code/ticket/17); I wonder whether darcs ought to apply to be a GSoC mentoring organisation in its own right this year? It would be good to attempt to get a couple of dedicated slots for darcs only (in addition to any that haskell.org may get). * Optimization of containers (http://hackage.haskell.org/trac/summer-of-code/ticket/1549). Would benefit every Haskell user very quickly. This was Jamie Brandon's GSoC project last year, and although that is not yet in wide use, I suspect there is very little extra effort needed to get it out there into the average Haskell user's hands. * XMonad compositing support (http://hackage.haskell.org/trac/summer-of-code/ticket/1548). Maybe XMonad should also think about whether to apply to GSoC in their own right as a mentoring org? As a project, it seems to have a lot of life independent of the Haskell community. By the way: I think it may be worthwile to contact Google to point out the recent growth of Haskell community. I don't know on what basis they assign the slots, but it may be beneficial to do so. In the past it has been based on scale of mentors, proposals and students. If we're under-allocated, that can sometimes be addressed, however. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Google Summer of Code 2009
gwern0: On Thu, Feb 12, 2009 at 11:49 AM, John Lato jwl...@gmail.com wrote: Johan Tibell wrote: On Thu, Feb 12, 2009 at 2:12 AM, Felipe Lessa felipe.le...@gmail.com wrote: Do we already have enough information to turn http://okmij.org/ftp/Haskell/Iteratee/ into a nice, generic, cabalized package? I think Iteratees may prove themselves as useful as ByteStrings. I still haven't figured out what the correct definition of Iteratee would look like. The Iteratee code that Oleg wrote seems to have the structure of some kind of two level monad. I think that's the reason for the frequent occurrences of == and liftI in the code. There seems to be some things we yet have to discover about Iteratees. I concur. I've recently been involved with several discussions on this topic, and there are some issues that remain. The two level monad part doesn't bother me, but I think the type should be slightly more abstract and I'm not sure of the best way to do so. IMO liftI is used more because of Oleg's particular style of coding than anything else. I don't think it need be common in user code, although it may be more efficient. I think that, if a GSOC project were to focus on Iteratees, it would need to look at issues like these. I can't judge as to whether this is an appropriate amount of work for GSOC, however simply packaging and cabal-izing Oleg's Iteratee work (or Johan's, or my own) is likely of too small a scope. John Lato I agree. Just packaging and cabalizing something is likely not a SoC-worthy project. (This is why the 'cabalize Wash' suggestion will never make it, for example.) In general, cabalizing seems to be either pretty easy (most everything I've cabalized) or next to impossible (gtk2hs, ghc). The former are too trivial for SoC, and the latter likely are impossible without more development of Cabal - at which point it'd be more correct to call it a Cabal SoC and not a cabalizing SoC. Yes, cabalising was more of a priority when we only had 10 libraries :) So in general, think hard about missing capabilities in Haskell: * tools * libraries * infrastructure that benefit the broadest number of Haskell users or developers. Another route is to identify a clear niche where Haskell could leap ahead of the competition, with a small investment. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is using Data.Dynamic considered a no-go?
bugfact: Haskell seems to have pretty strong support for dynamic casting using Data.Typeable and Data.Dynamic. All kinds of funky dynamic programming seems to be possible with these hacks. Is this considered as being as bad as - say - unsafePerformIO? What kind of evil is lurking here? Inefficiencies and runtime errors? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is using Data.Dynamic considered a no-go?
Notably, extensible exceptions use dynamics, in conjunction with type
classes and existentials.
A number of solutions to the 'expression problem' involve dynamics.
bugfact:
It would be interesting to see when you HAVE to use dynamics, e.g. when no
other solution is possible in Haskell...
Right now if I use it, it feels that I'm doing so because I'm too new to
Haskell.
On Thu, Feb 12, 2009 at 7:53 PM, Lennart Augustsson lenn...@augustsson.net
wrote:
You're quite right. You should only be allowed to derive Typeable.
(Which could be arranged by hiding the methods of typeable.)
On Thu, Feb 12, 2009 at 6:24 PM, Jonathan Cast
jonathancc...@fastmail.fm wrote:
On Thu, 2009-02-12 at 19:04 +0100, Lennart Augustsson wrote:
They are not unsafe in the way unsafePerformIO is,
I beg permission to demur:
newtype Unsafe alpha = Unsafe { unUnsafe :: alpha }
instance Typeable (Unsafe alpha) where
typeOf _ = typeOf ()
pseudoSafeCoerce :: alpha - Maybe beta
pseudoSafeCoerce = fmap unUnsafe . cast . Unsafe
Note that
pseudoSafeCoerce = Just . unsafeCoerce
but I regard them
as a last resort in certain situations.
Still, in those situations they are very useful.
But I would agree with both of these. As long as you *derive* Typeable.
jcc
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Re: [Haskell-cafe] Race condition possible?
bugfact: Consider the following code stamp v x = do t - getCurrentTime putMVar v (x,t) Is it possible - with GHC - that a thread switch happens after the t - getCurrentTime and the putMVar v (x,t)? Yes. if 't' is heap allocated, there could be a context switch. If so, how would it be possible to make sure that the operation of reading the current time and writing the pair to the MVar is an atomic operation, in the sense that no thread switch can happen between the two? Would this require STM? Using 'atomically' and TVars in STM, perhaps? Else, use withMVar? Or a modifyMVar in IO? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
gwern0: (The following is a quasi essay/list of past Summer of Code projects; my hope is to guide thinking about what Summer of Code projects would be good to pick, and more specifically what should be avoided. If you're in a hurry, my conclusions are at the bottom. The whole thing is written in Markdown; for best results pass it through Pandoc or view it via your friendly local Gitit wiki.) Thanks for the write up! We explicitly pushed harder in 2008 to clarify and simplify the goals of the projects, ensure adequate *prior Haskell experience* and to focus on libraries and tools that directly benefit the communtity. And our success rate was much higher. So: look for things that benefit the largest number of Haskell developers and users, and from students with proven Haskell development experience. You can't learn Haskell from zero on the job, during SoC. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
bulat.ziganshin: Hello Jamie, Wednesday, February 11, 2009, 5:54:09 AM, you wrote: Seems like it is ok to write H.264 in Haskell and released via GPL license? anyway it's impossible due to slow code generated by ghc Been a long time since you did high perf code -- we routinely now write code that previously was considered not feasible. However, I would say it needs an optimisation expert, yes, in any language. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell.org GSoC
d: Hi, I noticed last year Haskell.org was a mentoring organization for Google's Summer of Code, and I barely noticed some discussion about it applying again this year :) I participated for GCC in 2008 and would like to try again this year; while I'm still active for GCC and will surely stay so, I'd like to see something new at least for GSoC. And Haskell.org would surely be a very, very nice organization. Since I discovered there's more than just a lot of imperative languages that are nearly all the same, I love to do some programming in Prolog, Scheme and of course Haskell. However, so far this was only some toy programs and nothing really useful; I'd like to change this (as well as learning more about Haskell during the projects). Here are some ideas for developing Haskell packages (that would hopefully be of general use to the community) as possible projects: - Numerics, like basic linear algebra routines, numeric integration and other basic algorithms of numeric mathematics. I think a lot of the numerics stuff is now covered by libraries (see e.g. haskell-blas, haskell-lapack, haskell-fftw) - A basic symbolic maths package; I've no idea how far one could do this as a single GSoC project, but it would surely be a very interesting task. Alternatively or in combination, one could try to use an existing free CAS package as engine. Interesting, but niche, imo. - Graphs. - Some simulation routines from physics, though I've not really an idea what exactly one should implement here best. True graphs (the data structure) are still a weak point! There's no canonical graph library for Haskell. - A logic programming framework. I know there's something like that for Scheme; in my experience, there are some problems best expressed logically with Prolog-style backtracking/predicates and unification. This could help use such formulations from inside a Haskell program. This is surely also a very interesting project. Interesting, lots of related work, hard to state the benefits to the community though. What do you think about these ideas? I'm pretty sure there are already some of those implemented, but I also hope some would be new and really of some use to the community. Do you think something would be especially nice to have and is currently missing? Think about how many people would benefit. For example, if all the haddocks on hackage.org were a wiki, and interlinked, every single package author would benefit, as would all users. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC development
andrewcoppin: OK, so I have a small question. I was just wondering what the current state of development with GHC is. So, I had a look at the developer wiki. Unfortunately, as best as I can tell, most of the status pages haven't been updated in many months. (Most of them still talk about what will or won't be in 6.10.1, which has been *released* for a while now.) What's the best way to find out what the real state of affairs is? What are the developers really working on? What's on hold? How far have people got with things? Etc. (Yes, I know. I'm nosey...) GHC questions should go to glasgow-haskell-users, http://www.haskell.org/pipermail/glasgow-haskell-users/2009-February/thread.html To really see what is going on, look at the commit list and the bug tracker, http://www.haskell.org/pipermail/cvs-ghc/2009-February/thread.html Bug tracker, http://hackage.haskell.org/trac/ghc/query?status=newstatus=assignedstatus=reopenedgroup=prioritytype=bugorder=iddesc=1 These links are trivial to find from the GHC home page. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
bulat.ziganshin: Hello Don, Wednesday, February 11, 2009, 8:28:33 PM, you wrote: anyway it's impossible due to slow code generated by ghc Been a long time since you did high perf code -- we routinely now write code that previously was considered not feasible. which is still slower than C and need more time to write However, I would say it needs an optimisation expert, yes, in any language. there are experts, includingyou, in making haskell specific code as fast as possible, but i don't know anyone using haskell to write high-performance code. so you ask for non-existing specialists We're doing it at Galois regularly. Check out the blog. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re[4]: [Haskell] Google Summer of Code
bulat.ziganshin: Hello John, Wednesday, February 11, 2009, 11:55:47 PM, you wrote: it's exactly example of tight loop. and let's compare HP code written for this task with analogous code written in C. i expect that haskell code is much more complex I think it's fair to point out that tight loops are nearly always the biggest bottlenecks of code, so generating good code for tight loops is pretty important. it's important, but doesnt't make whole game. and while i said that ghc improved tight loops compilation, this doesn't mean that it becomes the same as in gcc. it just started to put loop variables into register And ghc is still making large improvements with each release, whereas gcc isn't likely to get significantly better. yes, it's close to perfect afaiu, it's 20-line equivalent of 2-line C code: for (i=...) a[i] = b[i] does this need any more comments? I think you've misunderstood my code. Look at Oleg's IterateeM and see if you think that's really all it's doing. what else does the code that you've citated? you are wrote that it just copies 16-bit words into doubles Use libsndfile for comparison. http://www.mega-nerd.com/libsndfile/. it's one method of miscomparing haskell to C - compare hand-tuned haskell code with some C code which may be just not optimal. ig you want to make fair comparison, you should write best code in both languages I actually haven't looked at the code, although it's very highly regarded in the audio community (and I've seen the author post on this list on occasion). Using libsndfile-1.0.18: wc wav.c 17867833 57922 wav.c compared to my source: wc Wave.hs 4122215 15472 Wave.hs And there you are. I will admit that I have implemented the entire wave spec, but only because of lack of time. when you don't need speed, you may write more compact code in haskell than in C. so the best way is to split your task into speed-critical part and the rest and use C++ for the first and Haskell for the second I think what's frustrating about this continued dialogue with Bulat re. performance is that , a) the experience he bases his remarks upon was several year ago b) he's making blanket generic statements, using that old data d) a lot of people have written a lot of fast code without trouble c) he's not acknowledging the great improvements over this time So its very difficult to have these conversations. They're stuck in the same old pattern. Meanwhile, GHC keeps getting smarter and smarter. Bulat: time to update your results! Check out what GHC is doing these days, and come back with an analysis of what still needs to be improved. We can't wait to hear! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
Thanks for the analysis, this clarifies things greatly. Feasibility and scope is a big part of how we determine what projects to work on. gtener: On Wed, Feb 11, 2009 at 21:00, Jamie hask...@datakids.org wrote: Hi Gwern, On Wed, 11 Feb 2009, Gwern Branwen wrote: I just checked H.263 and it looks like it does not require patent licensing at all (it is created by ITU-T Video Coding Experts Group (VCEG)) so one can write H.263 in Haskell and release freely without patent licensing issues. So writing H.263 in Haskell could be a good GSoC project. One mentioned that GHC produce slow code, well H.263 could be a good test case to improve GHC optimization over time. In The Computer Language Benchmarks Game, Haskell has some catching up to do. :) It does sound like a reasonably discrete task, and it sounds like you have a use for it; but I wonder if it's doable in a single summer? I have no idea, I have not dig deeper into H.263 C source code but I guess it should be quite trivial as it is a black box with video frame input and output with several parameters for encoding and just frame in/out for decoding. I didn't dig into the source code either, but I've just skimmed through Wikipedia page on that codec: http://en.wikipedia.org/wiki/H.263 and in seems far from trivial. Anything that has 23 annexes is likely to be quite complex :-) Therefore I seriously doubt chances for success of such project. I did some checks: in libavcodec at least following files consist of implementation of H.263: h263.c h263data.h h263dec.c h263.h h263_parser.c h263_parser.h How many lines are there? [te...@laptener libavcodec]$ wc h263* 6295 19280 218932 h263.c 314 2117 10423 h263data.h 816 2171 26675 h263dec.c 46217 2032 h263.h 91282 2361 h263_parser.c 29165 1047 h263_parser.h 7591 24232 261470 razem In Haskell project one would also need to provide some additional utility code which is part of libavcodec. Fast grep shows the tip of an iceberg: [te...@laptener libavcodec]$ grep include h263* | grep -v h263.c:#include dsputil.h h263.c:#include avcodec.h h263.c:#include mpegvideo.h h263.c:#include h263data.h h263.c:#include mpeg4data.h h263.c:#include mathops.h h263data.h:#include mpegvideo.h h263dec.c:#include avcodec.h h263dec.c:#include dsputil.h h263dec.c:#include mpegvideo.h h263dec.c:#include h263_parser.h h263dec.c:#include mpeg4video_parser.h h263dec.c:#include msmpeg4.h h263.h:#include config.h h263.h:#include msmpeg4.h h263_parser.c:#include parser.h h263_parser.h:#include parser.h Bottom line: I don't think it is reasonable to assume anyone without previous knowledge of H.263 is able to fit that project into one summer. But! It's Haskell community, and people here see the impossible happen from time to time ;-) All best Christopher Skrzętnicki ___ 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] Re[4]: [Haskell] Google Summer of Code
bulat.ziganshin: Hello Don, Thursday, February 12, 2009, 12:23:16 AM, you wrote: Check out what GHC is doing these days, and come back with an analysis of what still needs to be improved. We can't wait to hear! can you point me to any haskell code that is as fast as it's C equivalent? You should do your own benchmarking! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell] Google Summer of Code 2009
Malcolm.Wallace: Gentle Haskellers, The Google Summer of Code will be running again this year. Once again, haskell.org has the opportunity to bid to become a mentoring organisation. (Although, as always, there is no guarantee of acceptance.) If you have ideas for student projects that you think would benefit the Haskell community, now is the time to start discussing them on mailing lists of your choice. We especially encourage students to communicate with the wider community: if you keep your ideas private, you have a much worse chance of acceptance than if you develop ideas in collaboration with those who will be your customers, end-users, or fellow-developers. This is the open-source world! And I'll just note that since December we've been running a proposal submission site here, where you can vote and comment on ideas, http://www.reddit.com/r/haskell_proposals/top/ A great place to suggest ideas! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Asking the GHC garbage collector to run
mads_lindstroem: Hi all, Is it possible to ask the GHC garbage collector to run ? Something like a collectAllGarbage :: IO() call. System.Mem.performGC iirc, Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GMP on Mac OS X linked statically by default
leimy2k: Was there a reason for this? If so, it'd be nice if the package that was build explained why... otherwise it feels kind of arbitrary, and would be nice if there was documentation available to make it link dynamically in case someone didn't want to LGPL their program. Anyone know the steps to make it link dynamically? Here's how we do it on Windows. The Mac should be far easier, http://haskell.forkio.com/gmpwindows -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Gtk2HS 0.10.0 Released
Well done! Our flagship GUI bindings... Go team! -- Don pgavin: Hi everyone, Oh, dear... it seems I've forgotten how to spell cafe, and sent this message to haskell-c...@haskell.org the first time around. I resent it to all the lists again (just to make sure everyone interested receives it), so I apologize for any duplicated messages you might have received. In any case... I'd like to release the announcement of Gtk2HS 0.10.0. A lot of new stuff has gone into this release, including: - Support for GHC 6.10 - Bindings to GIO and GtkSourceView-2.0 - Full switch to the new model-view implementation using a Haskell model - Support for many more model-based widgets such as IconView and an updated binding for ComboBox - Full Drag-and-Drop support - Better support for Attributes in Pango - Replaced Event for EventM monad, thereby improving efficiency and convenience - Functions for interaction between Cairo and Pixbuf drawing - Lots of bug fixes, code cleanups, and portability improvements With this release, the bindings to GnomeVFS and GtkSourceView-1.0 have been deprecated. The TreeList modules have been deprecated from the Gtk+ bindings. Source and Win32 binaries are available at: https://sourceforge.net/project/showfiles.php?group_id=49207package_id=42440release_id=659598 Thanks to everyone who submitted bug fixes and features this time around! Thanks, Peter Gavin Gtk2HS Release Manager ___ 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] Efficient string output
ketil: Hi, I'm currently working on a program that parses a large binary file and produces various textual outputs extracted from it. Simple enough. But: since we're talking large amounts of data, I'd like to have reasonable performance. Reading the binary file is very efficient thanks to Data.Binary. However, output is a different matter. Currently, my code looks something like: summarize :: Foo - ByteString summarize f = let f1 = accessor f f2 = expression f : in B.concat [f1,pack \t,pack (show f2),...] which isn't particularly elegant, and builds a temporary ByteString that usually only get passed to B.putStrLn. I can suffer the inelegance were it only fast - but this ends up taking the better part of the execution time. Why not use Data.Binary for output too? It is rather efficient at output -- using a continuation-like system to fill buffers gradually. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: The Haskell re-branding exercise
marlowsd: Sterling Clover wrote: IP based limitations are a terrible idea. Multiple users can be and often are behind the same IP if they're in some sort of intranet, be it corporate, academic, or simply multiple home computers. Mail-based authentication can be screwed with, sure, but it's also very easy to notice this (as opposed to ip nonsense) through simply eyeballing the results. There's no general everywhere way to prevent vote fraud. However, if we make it even require a mild bit of thought, that should be sufficient in this case, as there won't be enough votes to prevent some sort of rough eyeball-based check of the results, and if there are, then that's a sign of fraud for sure! Furthermore, there's very little incentive for someone to go the extra mile here, as we're voting for a haskell logo, and not, e.g., giving away ten thousand dollars. Furthermore, since I assume we'll only be presenting reasonable logos, there's not even some room for pranksters to stage a write-in of some gag slogan. I suggest we do voting by email, and restrict voting to those who have ever posted on haskell-cafe before 1 Jan 2009. We could then have an auto-confirmation scheme similar to mailing list sign-up where the confirmation message is sent back to the originator to confirm their identity, containing a verification link to click on. I realise there are flaws in this, but it seems to be (a) cheap to implement and participate in, and (b) good enough. Seems good enough. Who's going to tally the votes? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] any implementation of ACIO?
jianzhou: Hi, http://www.haskell.org/pipermail/haskell-cafe/2004-November/007715.html mentioned an interesting (A)ffine and (C)entral IO. Are there any packages or extensions to support ACIO in Haskell? Not that I know of. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to link statically with a c lib ?
noteed: Hi, I'm writing bindings for the Tiny C Compiler. It seems that tcc provide a libtcc.a but no libtcc.so. In my cabal file, I have extra-libraries: dl, tcc but when using the generated haskell module, I have the following message : ⟨...@jones samples⟩ ghc -e main Test.hs interactive: command line: can't load .so/.DLL for: tcc (libtcc.so: cannot open shared object file: No such file or directory) How can I generate a module linked statically against libtcc ? Without a .so you can't load it in ghci, but you can compile it with ghc. ghc --make Test.hs -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to link statically with a c lib ?
noteed: 2009/2/8 Don Stewart d...@galois.com: noteed: Hi, I'm writing bindings for the Tiny C Compiler. It seems that tcc provide a libtcc.a but no libtcc.so. In my cabal file, I have extra-libraries: dl, tcc but when using the generated haskell module, I have the following message : ⟨...@jones samples⟩ ghc -e main Test.hs interactive: command line: can't load .so/.DLL for: tcc (libtcc.so: cannot open shared object file: No such file or directory) How can I generate a module linked statically against libtcc ? Without a .so you can't load it in ghci, but you can compile it with ghc. ghc --make Test.hs Ok but what should be written in the cabal file ? I build a .so of libtcc so it works for now. Before I put it on hackage, maybe I can get a review of it, if anything is fundamentaly wrong ? It is located at http://github.com/noteed/tcc/tree/master In the .cabal file should only be: extra-libraries: tcc I think. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: X Haskell Bindings 0.1
aslatter: I'd like to announce a version bump for the X Haskell Bindings (XHB) library, to 0.1.* from 0.0.*. The goal of XHB is to provide a Haskell implementation of the X11 wire protocol, similar in spirit to the X protocol C-language Binding (XCB). On Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/xhb This release focuses on making the API a bit friendlier: + 'type BOOL = Word8' has been replaced in the API by Prelude.Bool + type synonyms BYTE, CARD8, CARD16 and CARD32 for the Data.Word types have been eliminated + type synonyms INT8, INT16 and INT32 for the Data.Int types have been eliminated + Previously, all protocol replies were represented by their own distinct data type. Now, if the reply to a request only includes a single field, the request returns that field directly. In more concrete terms: internAtom :: Connection - InternAtom - IO (Receipt InternAtomReply) becomes: internAtom :: Connection - InternAtom - IO (Receipt ATOM) Further work to make the API more Haskelly is ongoing. Related projects: X C Bindings: http://xcb.freedesktop.org/ Well done! Have a distro package, http://aur.archlinux.org/packages.php?ID=23765 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
s.clover: IP based limitations are a terrible idea. Multiple users can be and often are behind the same IP if they're in some sort of intranet, be it corporate, academic, or simply multiple home computers. Mail-based authentication can be screwed with, sure, but it's also very easy to notice this (as opposed to ip nonsense) through simply eyeballing the results. There's no general everywhere way to prevent vote fraud. However, if we make it even require a mild bit of thought, that should be sufficient in this case, as there won't be enough votes to prevent some sort of rough eyeball-based check of the results, and if there are, then that's a sign of fraud for sure! Furthermore, there's very little incentive for someone to go the extra mile here, as we're voting for a haskell logo, and not, e.g., giving away ten thousand dollars. Exactly. Let's not wander down to the bikeshed :) Furthermore, since I assume we'll only be presenting reasonable logos, there's not even some room for pranksters to stage a write-in of some gag slogan. Right, only a subset of previously submitted ones. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
Furthermore, since I assume we'll only be presenting reasonable logos, there's not even some room for pranksters to stage a write-in of some gag slogan. Right, only a subset of previously submitted ones. -- Don So does this mean no 'haskell YEEHH!'? Isn't that already the underground official logo? http://www.facebook.com/pages/Haskell/56088385002 -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
paul: Paul Johnson wrote: A call has gone out http://www.haskell.org/pipermail/haskell-cafe/2008-December/051836.html for a new logo for Haskell. Candidates (including a couple http://www.haskell.org/haskellwiki/Image:Haskell-logo-revolution.png of mine http://www.haskell.org/sitewiki/images/f/fd/Ouroborous-oval.png) are accumulating here http://www.haskell.org/haskellwiki/Haskell_logos/New_logo_ideas. There has also been a long thread on the Haskell Cafe mailing list. So what's happening about this? We need a voting site set up. There was some progress prior to the end of the year. Updates welcome! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
wagner.andrew: We need a voting site set up. There was some progress prior to the end of the year. Updates welcome! -- Don Can't we just use the haskell proposal reddit for this? Hmm... not ideal. Would make a backup should all else fail. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
Oh, we had a long discussion about the need for condorcet voting, not a system like the reddit which is prone to abuse. Also, it would be good to have the images inline. wagner.andrew: Um, ok. Glad we could discuss it On Sat, Feb 7, 2009 at 1:12 PM, Don Stewart d...@galois.com wrote: wagner.andrew: We need a voting site set up. There was some progress prior to the end of the year. Updates welcome! -- Don Can't we just use the haskell proposal reddit for this? Hmm... not ideal. Would make a backup should all else fail. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Semantic web
dev: Anybody implementing rdf or owl stuff in haskell? Seems like a natural fit. http://www.ninebynine.org/RDFNotes/Swish/Intro.html Needs moving to Hackage. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
gwern0: On Sat, Feb 7, 2009 at 1:34 PM, Don Stewart d...@galois.com wrote: Oh, we had a long discussion about the need for condorcet voting, not a system like the reddit which is prone to abuse. Also, it would be good to have the images inline. Perfect, please meet better. Better, perfect. Now get along you two! Since January 1st, we could've had hundreds or thousands of votes and easily compensated for any abuse. Unfortunately, reddit isn't a suitable voting site, as submissions decay over time, dissappearing off the page after a day or two. It does have up and down mods, but in no other way is a voting site. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
gwern0: On Sat, Feb 7, 2009 at 3:04 PM, Don Stewart d...@galois.com wrote: gwern0: On Sat, Feb 7, 2009 at 1:34 PM, Don Stewart d...@galois.com wrote: Oh, we had a long discussion about the need for condorcet voting, not a system like the reddit which is prone to abuse. Also, it would be good to have the images inline. Perfect, please meet better. Better, perfect. Now get along you two! Since January 1st, we could've had hundreds or thousands of votes and easily compensated for any abuse. Unfortunately, reddit isn't a suitable voting site, as submissions decay over time, dissappearing off the page after a day or two. It does have up and down mods, but in no other way is a voting site. -- Don That's how the what's hot works, I understand. But it seems to me that Top works just fine for vote tallying purposes eg. http://www.reddit.com/r/haskell/top/ lists quite a few posts posted months ago (4 months seems to be the oldest). Quite so, biased by the fact that they dropped off the page. I'm not saying reddit is unsuitable for communal decision making -- I've thought hard about this -- just that isn't perfect, and this isn't really its purpose. It would make a good backup if we can't find a proper system. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
gwern0: 2009/2/7 Don Stewart d...@galois.com: Quite so, biased by the fact that they dropped off the page. I'm not saying reddit is unsuitable for communal decision making -- I've thought hard about this -- just that isn't perfect, and this isn't really its purpose. It would make a good backup if we can't find a proper system. -- Don And how long do we wait? Is a month long enough? 2 months? Do we just make a note on our calendars for February 2010 - 'get moving on that logo contest thing'? Help identifying and implementing a voting process is very welcome. Snarky comments are not. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] The Haskell re-branding exercise
bulat.ziganshin: Hello Don, Saturday, February 7, 2009, 8:20:23 PM, you wrote: We need a voting site set up. There was some progress prior to the end of the year. Updates welcome! i think that there are a lot of free voting/survey services available. the last one i went through was LimeSurvey available for any SF project and on separate site too http://apps.sourceforge.net/trac/sitedocs/wiki/Hosted%20Apps https://www.limeservice.com/ Before the new year's break, the progress we made towards deciding on a voting process was, http://groups.google.com/group/fa.haskell/msg/5d0ad1a681b044c7 Eelco implemented a demo condorcet voting system in HAppS. He then asked for help with some decisions: * Limit voting, if so how? Email confirmation, IP based, vote once, once per day? * Maybe don't show the results until the contest is over? Eelco, can we do simple email-based confirm to encourage people to vote only once, and can we keep the results closed until the vote process is over? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are you using Haskell on the job?
kirk.martinez: Hello, fellow Haskell hackers! I am writing a term paper on Haskell in Business, and while I have gathered a lot of good information on the Internet, I would really like direct feedback from software professionals who have used Haskell in a business setting. I would really appreciate a few minutes of your time to provide insights gained from applying Haskell in the real world. Who knows, this could lead to a greater adoption of Haskell in the business community! Rather than a list of Haskell's technical strengths (purity, laziness, composition, etc.), I want to get a sense of the process leading up to the decision to use Haskell for a given project and the insights gained during and after completion. I am particularly interested in questions related to business value: ● What were the pros and cons you considered when choosing a language? Why FP? Why Haskell? ● What aspects of your problem domain were most critical to making that choice? ● How has using Haskell given you a competitive advantage? ● How is the software development lifecycle positively/negatively affected by using Haskell as opposed to a different language? ● How did you convince management to go with a functional approach? ● Was the relative scarcity of Haskell programmers a problem? If so, how was it managed? ● Would you choose to use Haskell again for a similar project given what you know now? The best responses will not simply list answers, but also provide background and a bit of narrative on the project and insights gained. Feel free to reply to the list, or just to me personally if you prefer. My email is below. I would also suggest you contact speakers from past CUFP meetings, who've written all sorts of interesting summaries on the use of Haskell (and other FP langs) in industry. http://cufp.galois.com/ -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fastest regex package?
allbery: On 2009 Feb 5, at 10:26, Eugene Kirpichov wrote: My benchmark (parsing a huge logfile with a regex like GET /foo.xml.*fooid=([0-9]++).*barid=([0-9]++)) shows that plain PCRE is the fastest one (I tried PCRE, PCRE-light and TDFA; DFA can't do capturing groups at all, TDFA was abysmally slow (about 20x slower than PCRE), and it doesn't support ++), but maybe have I missed any blazing-fast package? I think dons (copied) will want to hear about this; pcre-light is supposed to be a fast lightweight wrapper for the PCRE library, and if it's slower than PCRE then something is likely to be wrong somewhere. Shouldn't be slower (assuming you're using bytestrings). -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell tutorial for pseudo users?
andrewcoppin: Deniz Dogan wrote: Learn You a Haskell for Great Good (http://learnyouahaskell.com/) Mmm, interesting. Does anybody else think it would be neat if GHCi really did colourise your input like that? (Or at least display the prompt in a different colour to user input and program output?) I wrote about this a while ago, http://haskell.org/haskellwiki/GHCi_in_colour Needs integration with ghc-api, and we're done. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Happstack 0.1 Released!
andrewcoppin: Jochem Berndsen wrote: The HAppS project has been abandoned, see http://groups.google.com/group/HAppS/msg/d128331e213c1031 . The Happstack project is intended to continue development. For more details, see http://happstack.com/faq.html . So we've got HAppS, Happstack, WASH, Turbinado, probably others... Does anybody know how all these relate to each other? Where their strengths and weaknesses lie? It's nice to have choice, but without knowing what you're choosing between, it's hard to use it well. A comparative analysis of the 10+ Haskell web frameworks would be awesome. happstack, wash, fastcgi.., turbinado, perpubplat, riviera, salvia, kibro, ella, what was that one launched yesterday? *ah, yesod... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: ANN: #haskell-in-depth IRC channel
We explicitly want to avoid a newbie trap See the summary of the discussion that lead to the channel creation http://haskell.org/haskellwiki/IRC_channel/Phase_2 -- Don DekuDekuplex: On Wed, 04 Feb 2009 00:15:48 +, Philippa Cowderoy fli...@flippac.org wrote: [...] If you need to know how to use monads so you can do IO, #haskell-in-depth isn't the place. On the other hand, if you want to discuss how Haskell's monads compare to the category theory or what the category theory can tell us about how individual monads relate to the language as a whole, -in-depth is a good place! In particular, we're hoping that the kind of category theory discussions that give the mistaken impression you actually need to know CT will increasingly live in #haskell-in-depth. We're not after a theory channel though - architectural discussion, compiler implementation, possible type system extensions, library design, all are good subjects. Great work! I look forward to participating sometime in the near future. In that case, for people who need to know how to use monads so that they can do IO, why not create a #haskell-beginners channel? I have occasionally read posts of some users who were hesitant to participate in #haskell until they learned enough to keep up with the discussions there. If neither #haskell nor #haskell-in-depth is appropriate, perhaps they would feel more comfortable in a Haskell-beginners-specific channel? -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 Furuike ya, kawazu tobikomu mizu no oto. -- Matsuo Basho^ ___ 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] Re: 1,000 packages, so let's build a few!
ndmitchell: Hi So actually just having more Windows users subscribed to cabal-devel and commenting on tickets would be very useful, even if you do not have much time for hacking. I believe that as soon as a Windows user starts doing that you'll start asking them for patches :-) There are a number of reasons that we have fewer Windows developers: * Some of it comes down to social reasons - for some reason it seems to be socially acceptable to belittle Windows (and Windows users) on the Haskell mailing lists and #haskell. * Some of it comes down to technical issues - for example not having cabal.exe bundled with GHC 6.10.1 on Windows was a massive mistake (although I've heard everyone argue against me, I've not yet heard a Windows person argue against me). * Part of it comes down to most developers not being Windows people. * A little is because Windows is a second class citizen even in the libraries, my OS is NOT mingw32 - mingw32 is not even an OS, its a badly typed expression! How would you like it if your OS was listed as Wine? Things like this tell me that Haskell isn't Windows friendly, at best its windows tolerant. * Things like Gtk2hs, which Windows users need building for them, don't release in sync with GHC, which makes it hard to use. * Windows machines don't usually have a C compiler, and have a very different environment - while the rest of the world is starting to standardise. I gave up on fighting the fight when people decided not to bundle cabal.exe with Windows - and now I'm too busy with my day job... Now I'd say Duncan is the most vocal and practical Windows developer, even overlooking the fact he doesn't run Windows. GHC doesn't bundle with cabal-install on any system. What is needed is not for the GHC team to be doing Windows platform packages, but for the Windows Haskell devs to build their own system, as happens on all the Unices. Take GHC's release, wrap it up with native installers, throw in useful libraries and executables like cabal. Done. It's not the GHC compiler team's job to build distro-specific bundles. So, wind...@haskell.org anyone? Get the wiki going, get the set of tasks created. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Verifying Haskell Programs
pocmatos: Hi all, Much is talked that Haskell, since it is purely functional is easier to be verified. However, most of the research I have seen in software verification (either through model checking or theorem proving) targets C/C++ or subsets of these. What's the state of the art of automatically verifying properties of programs written in Haskell? State of the art is translating subsets of Haskell to Isabelle, and verifying them. Using model checkers to verify subsets, or extracting Haskell from Agda or Coq. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: 1,000 packages, so let's build a few!
jwlato: Duncan Coutts wrote: Some are trivial and should be done away with. For example the ones that just check if a C header / lib is present are unnecessary (and typically do not work correctly). The next point release of Cabal can do these checks automatically, eg: Configuring foo-1.0... cabal: Missing dependencies on foreign libraries: * Missing header file: foo.h * Missing C libraries: foo, bar, baz This problem can usually be solved by installing the system packages that provide these libraries (you may need the -dev versions). If the libraries are already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where they are. Thank you! Thank you! Thank you! For those of us who want to write cross-platform (i.e. Windows) bindings to C libraries, this is great news. It will be important now to report the lack of uses of these portability tests back to the authors of packages. A start would be to have hackage warn, I suppose. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: 1,000 packages, so let's build a few!
ganesh.sittampalam: Don Stewart wrote: GHC doesn't bundle with cabal-install on any system. What is needed is not for the GHC team to be doing Windows platform packages, but for the Windows Haskell devs to build their own system, as happens on all the Unices. Take GHC's release, wrap it up with native installers, throw in useful libraries and executables like cabal. Done. It's not the GHC compiler team's job to build distro-specific bundles. So, wind...@haskell.org anyone? Get the wiki going, get the set of tasks created. Isn't the Haskell Platform going to do all this? Shouldn't interested people just help out there? The platform is a set of blessed libraries and tools. The distros will still need to package that. To do that for Windows, we're still going to need a windows packaging team, along side Debian, Arch, Gentoo, Mac etc. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Verifying Haskell Programs
dbueno: On Mon, Feb 2, 2009 at 15:04, Don Stewart d...@galois.com wrote: pocmatos: Hi all, Much is talked that Haskell, since it is purely functional is easier to be verified. However, most of the research I have seen in software verification (either through model checking or theorem proving) targets C/C++ or subsets of these. What's the state of the art of automatically verifying properties of programs written in Haskell? State of the art is translating subsets of Haskell to Isabelle, and verifying them. Using model checkers to verify subsets, or extracting Haskell from Agda or Coq. Don, can you give some pointers to literature on this, if any? That is, any documentation of a verification effort of Haskell code with Isabelle, model checkers, or Coq? (It's not that I don't believe you -- I'd be really interested to read it!) All on haskell.org, http://haskell.org/haskellwiki/Research_papers/Testing_and_correctness#Verifying_Haskell_programs And there's been work since I put that list together. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Complex C99 type in Foreign
briqueabraque: Hi, Are there plans to include C99 'complex' type in Foreign, maybe as CFloatComplex, CDoubleComplex and CLongDoubleComplex? This seems an easy addition to the standard and would allow binding of a few interesting libraries, like GSL. A separate library for new types to add to Foreign would be the easiest way forward. Just put the foreign-c99 package on Hackage? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen 0.8.3 install problems
alistair: You can probably just remove the Setup.lhs and build with defaults (we're doing that at galois, we use Takusen). -- Don I'm surprised this works, unless you also change the imports of Control.Exception to Control.OldException. The new exception module is part of the reason it's taking me a while to port to 6.10.1. Nearly there though; only the haddock failures to fix and then we can release. build-depends: base 4 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Complex C99 type in Foreign
briqueabraque: Are there plans to include C99 'complex' type in Foreign, maybe as CFloatComplex, CDoubleComplex and CLongDoubleComplex? This seems an easy addition to the standard and would allow binding of a few interesting libraries, like GSL. A separate library for new types to add to Foreign would be the easiest way forward. Just put the foreign-c99 package on Hackage? As far as I know, this is not possible. (I tried for a long time to do that, actually, until I reallized it could not be done.) If it's not true, i.e., I could actually have some arbitrary sized parameter as argument to a function or as a return value (and not its pointer), what did I saw wrong? I understand only Foreign.C.C* types or forall a. = Foreign.Ptr.Ptr a can be used like that. Oh, you mean you need to teach the compiler about unboxed complex types? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen 0.8.3 install problems
praki.prakash: I am trying to install Takusen 0.8.3 with ghc 6.10.1 on Ubuntu 8.04 (same issue on Win XP as well). I get the following complaint from cabal. Module `Distribution.PackageDescription' does not export `writeHookedBuildInfo' cabal: Error: some packages failed to install: Takusen-0.8.3 failed during the configure step. The exception was: exit: ExitFailure 1 You can probably just remove the Setup.lhs and build with defaults (we're doing that at galois, we use Takusen). -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] 1,000 packages, so let's build a few!
andrewcoppin: In celebration of Hackage reachin over 1,000 unique packages, I decided that I would re-visit the problem of attempting to build them on Windows. Ah yes, I already have the tarball for stream-fusion-0.1.1, but I see that the latest release is 0.1.2.1. (Unfortunately, there doesn't appear to be any way to determine what the difference is between the two versions...) the true way to install all of hackage is: cabal install $(all my packages) where cabal install solves it all. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] 1,000 packages, so let's build a few!
bugfact: the true way to install all of hackage is: cabal install $(all my packages) where cabal install solves it all. not really :) e.g. my output on a Windows Vista system with GHC 6.10.1 cabal install sdl Resolving dependencies... Downloading SDL-0.5.4... [1 of 1] Compiling Main ( C:\Users\Peter\AppData\Local\Temp\TMPSDL-0.5.4\SDL-0.5.4\Setup.lhs, C:\Users\Peter \AppData\Local\Temp\TMPSDL-0.5.4\SDL-0.5.4\dist\setup\Main.o ) C:\Users\Peter\AppData\Local\Temp\TMPSDL-0.5.4\SDL-0.5.4\Setup.lhs:2:2: Warning: In the use of `defaultUserHooks' (imported from Distribution.Simple): Deprecated: Use simpleUserHooks or autoconfUserHooks, unless you need Cabal-1.2 compatibility in which case you must stick with defaultUserHooks Linking C:\Users\Peter\AppData\Local\Temp\TMPSDL-0.5.4\SDL-0.5.4\dist\setup\setup.exe ... Warning: defaultUserHooks in Setup script is deprecated. Configuring SDL-0.5.4... setup.exe: sh: runGenProcess: does not exist (No such file or directory) cabal: Error: some packages failed to install: SDL-0.5.4 failed during the configure step. The exception was: exit: ExitFailure 1 Isn't this missing C library dependencies, which cabal head now warns about? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Takusen 0.8.3 install problems
build-type: Simple praki.prakash: Don, Thanks for the hint. I removed Setup.hs and tried cabal build. I get an error that build type is custom and Setup.lhs is missing. What is the magical incantation needed to do the default build? Thanks Praki On Sat, Jan 31, 2009 at 12:30 PM, Don Stewart d...@galois.com wrote: praki.prakash: I am trying to install Takusen 0.8.3 with ghc 6.10.1 on Ubuntu 8.04 (same issue on Win XP as well). I get the following complaint from cabal. Module `Distribution.PackageDescription' does not export `writeHookedBuildInfo' cabal: Error: some packages failed to install: Takusen-0.8.3 failed during the configure step. The exception was: exit: ExitFailure 1 You can probably just remove the Setup.lhs and build with defaults (we're doing that at galois, we use Takusen). -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] 1,000 packages, so let's build a few!
sebastian.sylvan: -- From: Don Stewart d...@galois.com Sent: Saturday, January 31, 2009 8:35 PM To: Andrew Coppin andrewcop...@btinternet.com Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] 1,000 packages, so let's build a few! andrewcoppin: In celebration of Hackage reachin over 1,000 unique packages, I decided that I would re-visit the problem of attempting to build them on Windows. Ah yes, I already have the tarball for stream-fusion-0.1.1, but I see that the latest release is 0.1.2.1. (Unfortunately, there doesn't appear to be any way to determine what the difference is between the two versions...) the true way to install all of hackage is: cabal install $(all my packages) where cabal install solves it all. If that had actually worked it would be great I must say that my own not-so-random sampling (basically ooh that looks cool, let's try it) is probably at a 20% success rate or so... It's great when it does work, but it usually doesn't. Usually it fails because some part of it tries to run unix shell scripts (and I try to avoid things which seem like they're unix only, even though they're no easy way of determining this, so these are packages that at least to me seemed like they could be perfectly portable if not for unix-specific installation procedures). Windows people need to set up a wind...@haskell.org to sort out their packaging issues, like we have for debian, arch, gentoo, freebsd and other distros. Unless people take action to get things working well on their platform, it will be slow going. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] unboxed, functional ATS language beats C++
Note the inline C as well. agocorona: [1]Language Shootout: ATS is the new top gunslinger. Beats C++ [2]http://www.reddit.com/r/programming/comments/72hmw/language_shootout_ats_is_the_new_top_gunslinger/ ...Many people somehow think that ATS is fast because of its support for advanced types such as dependent types and linear types. Actually, types are primarily for enhancing safety rather than speed. The efficiency of ATS is largely rooted in its data representation (flat instead of boxed) and its support for tail-call optimization, which is vital for a functional language. What is interesting abut this ML derived language is the speed. The theoriem proving facilities seems like a language extensions for property checkings mainly for his non pure features. The type system seems to aid on the safety of pointer arithmetics and other dangerous operations. References Visible links 1. http://shootout.alioth.debian.org/u64q/benchmark.php?test=alllang=all 2. http://www.reddit.com/r/programming/comments/72hmw/language_shootout_ats_is_the_new_top_gunslinger/ ___ 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
[Haskell-cafe] Arch Haskell News: Jan 24 2009
A regular update of Haskell in Arch Linux http://archhaskell.wordpress.com/2009/01/24/arch-haskell-news-jan-24-2009/ * Arch now has 864 Haskell packages in AUR. That’s an increase of 37 new Haskell packages in the last 13 days, or 2.8 new Haskell apps and libraries a day packaged so far in January. Cheers, Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: gitit 0.5
Thanks for this! I'm a daily, heavy gitit user, and am happy to see continued improvements to this excellent app. -- Don jgm: We are pleased to announce the latest release of Gitit, the multitalented distributed wiki written in Haskell. What's new in this release? * 'Gitit' is now something of a misnomer, as Gitit now makes use of the filestore library. The upshot is that Gitit can now work in Darcs repositories; if before you thought Gitit was cool but didn't like git, you now have no excuse! * Gitit has been optimized (thanks to the efforts of Gwern Branwen): - Pages are now gzipped whenever possible. - Expire headers are set so that CSS, images, and javascripts will be cached by the browser. - Those previously mentioned elements have been optimized for space, and rearranged in the generated pages for faster rendering. * A new configuration option allows reStructuredText to be used instead of markdown (thanks to a patch from Simon Michael). * Gitit now sports a 'Go' box. You can now either search through Search, or go to a specific page title via Go. * Search is smarter, and can also return page titles. * Revisions are better formatted: the author field now include the user's email as well. * Diffs are of much higher quality, thanks to filestore. * UTF8-related fixes. You can check out a running example at http://gitit.johnmacfarlane.net/. Or try it locally: cabal update cabal install -fhighlighting pandoc gitit gitit # note: this will create two subdirectories in the working directory # then browse to http://localhost:5001. The git repository for Gitit is at http://github.com/jgm/gitit/tree/master ___ 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] Processor availability
wasserman.louis: How might I go about finding out how many processors are available in a concurrent GHC program? I have some code I'd like to parallelize, but I don't want to spawn a separate (even lightweight) thread for each of thousands of minor tasks. Louis Wasserman [1]wasserman.lo...@gmail.com You set the number of OS threads with +RTS -N at runtime. This value is accessible from Haskell via: GHC.Conc: -- | the value passed to the @+RTS -N@ flag. This is the number of -- Haskell threads that can run truly simultaneously at any given -- time, and is typically set to the number of physical CPU cores on -- the machine. numCapabilities :: Int -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] 1000 libraries
We've done it! http://hackage.haskell.org/cgi-bin/hackage-scripts/stats 274 users have uploaded 3161 versions of 1000 packages. Thanks everyone who has written a library or tool or app and released it, for making hackage and cabal a success! This has gone further, perhaps more than anything else, towards making it possible to use Haskell in industry. The lucky 1000th package is: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/threadPool-0.1 threadPool: Runs other programs in the manner of a thread pool Takes a single, optional argument which is the number of threads (the default is three). Give it the commands to run, one per line, through standard input. Author Brian Jaress Now, onto 10k libraries! -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Pure Haskell implementation of Float type?
catamorphism: Hello, Is there a pure Haskell implementation of Floats, i.e., one that (unlike GHC.Float) doesn't use foreign calls for things like isFloatNegativeZero? I don't care about performance; I'm just looking for something that doesn't use foreign calls. Huh, what's the use case? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Why monoids will abide...
http://apfelmus.nfshost.com/monoid-fingertree.html Thanks Apfelmus for this inspiring contribution! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] plugins can not be installed in ghc 6.10.1
agocorona: Do really pluigins needs Cabal (=1.4 1.5) ??? C:\Documents and Settings\Administratorcabal install plugins Resolving dependencies... cabal: dependencies conflict: ghc-6.10.1 requires Cabal ==1.6.0.1 however Cabal-1.6.0.1 was excluded because plugins-1.3.1 requires Cabal ==1.4.* Patches welcome. Probably switching to the 1.6 API won't be too hard. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell WikiProject
greenrd: Is anyone else interested in forming a Haskell WikiProject on Wikipedia, to collaborate on improving and maintaining the coverage and quality of articles on Haskell-related software and topics (broadly defined)? Not just programming topics specific to Haskell, but also ones of interest to the Haskell community. Some of you might already be doing this from time to time, but forming an explicit WikiProject might help to: * Highlight things that could use some attention * Divide up tasks (based on expertise or interest) * Recruit more editors (sticking a banner on article Talk pages can let editors know the WikiProject exists) * Eventually (something for the future, maybe!) work together on a Wikipedia Haskell Portal * And of course, improve the visibility of Haskell on Wikipedia, which should help our community Here's a good example to start with. The article on Eager evaluation could do with some improvement - and possibly should be merged into the Lazy evaluation article, I'm not sure: http://en.wikipedia.org/wiki/Eager_evaluation We could also probably create some more articles on projects written in Haskell, and add more references to Haskell research papers. Software projects don't have to be polished to be covered in Wikipedia - or even working! - they essentially just have to be notable, as the Wikipedia guidelines define it. By the way (getting a bit offtopic here) an annoying limitation of the Wikipedia category system, that you couldn't run queries like Give me all the articles in the Haskell category that are also in the Unreferenced category has now been partially addressed by the experimental prototype of Category Intersection: http://toolserver.org/~dschwen/intersection/ This is slightly better than Googling, because crucially, it searches *recursively* through categories. That means it will turn up articles that are in a subcategory of Category:Haskell programming language but don't explicitly mention Haskell. Don't know if there any such articles yet, but it's worth bearing in mind that you can do this. I think it will, in principle, make topic-specific maintenance a bit more convenient - and it's what I've been waiting for before getting involved in topic-specific maintenance. If you want to just express interest in signing up for such a WikiProject (no commitment required whatsoever!), please reply privately via email or publicly on my User Talk page (User talk:Greenrd) - to avoid clogging up this mailing list. Yes! Also, we have many good writers who've written extensively on topics on blogs who I'm sure would be happy to donate content. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Employment
And of course, there's at least half a dozen people on this list at working at Galois. And all documented on the wiki, http://haskell.org/haskellwiki/Haskell_in_industry See you guys at CUFP 09! http://cufp.galois.com/ -- Don pbeadling: Barclays Capital use it for Equity Derivative modeling and pricing - it's a small team at the moment, but the whole project is in Haskell. I don't work on it myself so I couldn't give you any details (plus I would get fired for blabbing!), I work in an adjacent group. Haskell certainly lends itself to complex financial maths simulation tho, so I think they've made a good choice. On 19/01/2009 19:34, Andrew Coppin andrewcop...@btinternet.com wrote: Is it possible to earn money using Haskell? Does anybody here actually do this? Inquiring minds want to know... ;-) ___ 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 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Optimistic evaluation
andrewcoppin: Hi folks. I just read a rather interesting paper about a fork of GHC that performs optimistic evaluation. This shows big wins in some cases. The authors claim to have implemented this in a fork of GHC and promised that it would be integrated into the production compiler in the near future. Curios, I investigated the GHC wiki... Well, let's see now. The front page has links to out release plans for 6.8.3 and what will be in 6.10. The latter page, http://hackage.haskell.org/trac/ghc/wiki/Status/Releases mentions that a beta has just been released... and seems oblivious to the fact that 6.10.1 is production now. Clearly, any hopes I might have had of getting a handle on the current status of GHC from this wiki were dashed somewhat. ;-) Does anybody have any suggestions for a more reliable way of figuring out what the current activities and plans for GHC are? I'm assuming you're talking about the 'eager evaluation' papers? (There were a few). I think the verdict was that the runtime machinery was too complex for the performance gain. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] runghc Setup.hs doitall
duncan.coutts:
On Sun, 2009-01-18 at 17:58 +0100, Daniel Fischer wrote:
Am Sonntag, 18. Januar 2009 17:22 schrieb Sebastian Sylvan:
Is there some sort of bundle that you can use to install cabal-install
easily? Because it looks to me like I'd have to spend the better part of
an
evening manually downloading and installing the gazillion of dependencies
it has, which is far too much work when I just wanted to spend ten minutes
playing with some package...
Wait, 'gazillion of dependencies'? If you have the extralibs bundle built,
there are only three dependencies to take care of
- a recent Cabal library
- HTTP
- zlib
I think the problem is that hackage is misleading. It looks from the
hackage page like there are a gazillion dependencies when in fact as you
say there are only 2 that are not included with the latest ghc.
The solution some have suggested would be for hackage to only list
dependencies that are not in some core set.
Hmm. That's interesting. As we do in the distro tools, for example,
makedepends=('ghc=6.10.1' 'haskell-http4000' 'haskell-zlib')
http://repos.archlinux.org/viewvc.cgi/community/devel/cabal-install/PKGBUILD?revision=1.1root=communitypathrev=CURRENT
So the distro packaging tools already have the 'implicit set' of things
we know are on the system if ghc is on it too.
-- Don
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Re: [Haskell-cafe] Comments from OCaml Hacker Brian Hurt
ross: On Sat, Jan 17, 2009 at 09:12:32PM -0500, a...@spamcop.net wrote: And FWIW, I agree with everyone who has commented that the documentation is inadequate. It'd be nice if there was some way to contribute better documentation without needing checkin access to the libraries. There is. The current state of the docs may be viewed at http://www.haskell.org/ghc/dist/current/docs/libraries/ Anyone can check out the darcs repos for the libraries, and post suggested improvements to the documentation to librar...@haskell.org (though you have to subscribe). It doesn't even have to be a patch. Sure, it could be smoother, but there's hardly a flood of contributions. I imagine if we set up a wiki-like system where the entire hackage docs could be edited, as well as viewed, we would end up with a flood. A modification to haddock perhaps, that sends edits to generated docs to libraries@ ? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Anybody in Savannah?
ketil: Hi, I arrived in Savannah yesterday (to attend PADL), and have spent the most part of the day drifting aimlessly around. Thrilling as that may be, I thought perhaps there might be other members of the Haskell community around, and that perhaps we could arrange to meet informally for coffee, beer, dinner? Some Galwegians will be at POPL and related events. http://www.galois.com/blog/2009/01/18/galois-at-popl/ Say hi to them :) -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Comments from OCaml Hacker Brian Hurt
david.waern: 2009/1/18 Don Stewart d...@galois.com: ross: On Sat, Jan 17, 2009 at 09:12:32PM -0500, a...@spamcop.net wrote: And FWIW, I agree with everyone who has commented that the documentation is inadequate. It'd be nice if there was some way to contribute better documentation without needing checkin access to the libraries. There is. The current state of the docs may be viewed at http://www.haskell.org/ghc/dist/current/docs/libraries/ Anyone can check out the darcs repos for the libraries, and post suggested improvements to the documentation to librar...@haskell.org (though you have to subscribe). It doesn't even have to be a patch. Sure, it could be smoother, but there's hardly a flood of contributions. I imagine if we set up a wiki-like system where the entire hackage docs could be edited, as well as viewed, we would end up with a flood. A modification to haddock perhaps, that sends edits to generated docs to libraries@ ? This has come up many times lately. I've created a ticket for it: http://trac.haskell.org/haddock/ticket/72 If anyone has suggestions for design or implementation of a system like this, don't hesitate to post to this ticket! Added to the entry on the proposals tracker, http://www.reddit.com/r/haskell_proposals/ If nothing else, this would make a good SoC project. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Slow Text.JSON parser
It occurs to me you could also use attoparsec, which is specifically
optimised for bytestring processing.
sjoerd:
Hi,
Somebody told me about Parsec 3, which uses a Stream type class so it
can parse any data type. This sounded like the right way to do
encoding independent parsing, so I decided to see how it would work to
parse UTF8 JSON.
Sadly I could not use Text.JSON.Parsec directly, because it uses the
old Parsec CharParser type. So I copied to code, and also replaced
p_number with the floating parser from Text.Parsec.Token, because
Text.JSON.Parsec uses readFloat (a dirty hack imho) which works only
on String.
If Text.JSON.Parsec was written for Parsec 3, the only thing to write
to get UTF8 JSON parsing would be:
instance (Monad m, U.UTF8Bytes string index) = Stream (U.UTF8 string)
m Char where
uncons = return . U.uncons
I did not do any performance measuring yet, I was glad I got it
working. Any comments on the code is appreciated!
greetings,
Sjoerd Visscher
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses,
UndecidableInstances #-}
import qualified Data.String.UTF8 as U
import qualified Data.ByteString as B
import Text.Parsec hiding (many, optional, (|))
import Control.Applicative
import Text.JSON.Types
import Control.Monad
import Data.Char
import Numeric
instance (Monad m, U.UTF8Bytes string index) = Stream (U.UTF8 string)
m Char where
uncons = return . U.uncons
type CharParser st = Parsec (U.UTF8 B.ByteString) st
parseFile :: FilePath - IO (Either ParseError JSValue)
parseFile fileName = do
bs - B.readFile fileName
return $ runParser json () fileName (U.fromRep bs)
parseString :: String - Either ParseError JSValue
parseString s = runParser json () (unknown) (U.fromString s)
json :: CharParser () JSValue
json = spaces * p_value
tok :: CharParser () a - CharParser () a
tok p = p * spaces
p_value :: CharParser () JSValue
p_value = (JSNull $ p_null)
| (JSBool $ p_boolean)
| (JSArray $ p_array)
| (JSString$ p_js_string)
| (JSObject$ p_js_object)
| (JSRational False $ p_number)
? JSON value
p_null :: CharParser () ()
p_null= tok (string null) return ()
p_boolean:: CharParser () Bool
p_boolean = tok
( (True $ string true)
| (False $ string false)
)
p_array :: CharParser () [JSValue]
p_array = between (tok (char '[')) (tok (char ']'))
$ p_value `sepBy` tok (char ',')
p_string :: CharParser () String
p_string = between (tok (char '')) (char '') (many p_char)
where p_char= (char '\\' p_esc)
| (satisfy (\x - x /= '' x /= '\\'))
p_esc = ('' $ char '')
| ('\\' $ char '\\')
| ('/' $ char '/')
| ('\b' $ char 'b')
| ('\f' $ char 'f')
| ('\n' $ char 'n')
| ('\r' $ char 'r')
| ('\t' $ char 't')
| (char 'u' * p_uni)
? escape character
p_uni = check = count 4 (satisfy isHexDigit)
where check x | code = max_char = pure (toEnum code)
| otherwise = empty
where code = fst $ head $ readHex x
max_char = fromEnum (maxBound :: Char)
p_object :: CharParser () [(String,JSValue)]
p_object = between (tok (char '{')) (tok (char '}'))
$ p_field `sepBy` tok (char ',')
where p_field = (,) $ (p_string * tok (char ':')) * p_value
p_number :: CharParser () Rational
p_number = tok floating where
floating :: CharParser () Rational
floating= do{ n - decimal
; fract - option 0 fraction
; expo - option 1 exponent'
; return ((fromInteger n + fract)*expo)
}
fraction= do{ char '.'
; digits - many1 digit ? fraction
; return (foldr op 0 digits)
}
? fraction
where
op d f= (f + fromIntegral (digitToInt d))/10
exponent' = do{ oneOf eE
; f - sign
; e - decimal ? exponent
; return (power (f e))
}
? exponent
where
power e | e 0 = 1/power(-e)
| otherwise = fromInteger
Re: [Haskell-cafe] ANNOUNCE: Coadjute 0.0.1, generic build tool
matti.niemenmaa+news: Announcing the release of Coadjute, version 0.0.1! Web site: http://iki.fi/matti.niemenmaa/coadjute/ Hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/Coadjute Here's an Arch Linux package for it, http://aur.archlinux.org/packages.php?ID=23237 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: Coadjute 0.0.1, generic build tool
ilmari.vacklin: 2009/1/18 Matti Niemenmaa matti.niemenmaa+n...@iki.fi: Announcing the release of Coadjute, version 0.0.1! Hi, trying to build on GHC 6.10.1 I get: Building regex-dfa-0.91... Text/Regex/DFA/Common.hs:6:7: Could not find module `Data.IntMap': it is a member of package containers-0.2.0.0, which is hidden cabal: Error: some packages failed to install: Coadjute-0.0.1 depends on regex-dfa-0.91 which failed to install. regex-dfa-0.91 failed during the building phase. The exception was: exit: ExitFailure 1 regex-dfa needs this patch, attached. Or use the native package for it on your distro ... :) -- Don --- regex-dfa.cabal.old 2009-01-17 16:10:53.0 -0800 +++ regex-dfa.cabal 2009-01-17 16:12:26.0 -0800 @@ -13,7 +13,7 @@ Description:The lazy DFA engine, based on CTKLight, for regex-base Category: Text Tested-With:GHC -Build-Depends: regex-base = 0.80, base = 2.0, parsec, mtl +Build-Depends: regex-base = 0.80, containers, base = 2.0, bytestring, parsec, mtl, array -- Data-Files: -- Extra-Source-Files: -- Extra-Tmp-Files: @@ -37,7 +37,7 @@ -- HS-Source-Dirs: . Extensions: MultiParamTypeClasses, FunctionalDependencies -- GHC-Options:-Wall -GHC-Options:-Wall -Werror -O2 +GHC-Options:-Wall -O2 -- GHC-Options:-Wall -ddump-minimal-imports -- GHC-Prof-Options: -- Hugs-Options: ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hackage about to reach 1000 releases
Hackage is about to reach the 1000 release mark, 2 years after it went live. That's right: in 2 years we've gone from having only a handful of released projects, to one thousand! Well done everyone! I did some quick visualisation of the rate of new releses, diversity of packages, and community growth over the period: http://archhaskell.wordpress.com/2009/01/18/open-source-haskell-releases-and-growth/ I'm very happy about the diversity of hackage apps, and the pleasing rate of growth of new releases. None of this would have been possible with out thousands of hours of work from the Cabal and Hackage hackers, the compiler teams, and the developers themselves. Keep churning out new and intresting code everyone! -- Don P.S. cabal install ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What could be considered standard Haskell these days?
briqueabraque: Hi, I would like to take some time to study Haskell properly, so that I could help others and pay my debt for the many times I had to bother with my syntax questions. And, of course, make better use of the language. My first attempt was to read the syntax description in Haskell 98 report, and that helped a lot. But I've realized that it's far from the language as used today. But just adding all available extensions would not be good, as some are very experimental e others are obsolete. I saw Haskell-prime page and a few features are marked as accepted. That mean I can trust them to be part of the next Haskell standard? So: if someone wants to learn the details of the language, what could be the subset of extensions one should learn and make regular use, and also include in code supposed to be used by others in the long term? Have a look at the accepted extensions for Haskell Prime. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: HTTPbis / HTTP-4000.x package available
lemming: On Thu, 15 Jan 2009, Sigbjorn Finne wrote: I guess it's time to publish more widely the availability of a modernization of the venerable and trusted HTTP package, which I've been working on offon for a while. I was always afraid that a fork may happen during I work on HTTP in order to get it more lazy. That's why I started discussion on web-devel mailing list, but got only limited response. I also notified Bjorn, that my changes need still a little time and that I'm worried about darcs conflicts. Seems that we now run into a perfect conflict. I don't like to throw away the work that I have done the last weeks. My version is at http://code.haskell.org/~thielema/http/ There's absolutely no need to throw away work. Hackage is a broad church, release it as http-lazy, at the very least. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell not ready for Foo [was: Re: Hypothetical Haskell job in New York]
john: On Jan 15, 2009, at 9:31 AM, John Goerzen wrote: By pure do you mean containing python code only? I'm looking through a few, and: Search for pure python mysql or pure python postgresql and you'll see at least two implementations. In addition, there are plenty of pure Python databases for those who want and are able to stay strictly within Python. FWIW, there are pure Haskell storage APIs. See e.g. HAppS-State and TCache. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
