Re: [Haskell-cafe] hoogle down
Hi Keith, Thanks for pointing this out. I've no idea why it's failing, but will check once I get home - unfortunately the machine I'm currently on doesn't permit me to ssh in and find out. Thanks, Neil On Sat, Nov 28, 2009 at 6:53 AM, Keith Sheppard keiths...@gmail.com wrote: hoogle is down for me: Internal Server Error Thanks Keith -- keithsheppard.name ___ 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] Custom cabal languages (hooks?)
I'm currently working on a binding to Brian Gladman's C/assembler AES implementation. This code is sufficiently small that it makes little sense to create a separate C library for it; furthermore, it isn't typically packaged by the various linux distributions, never mind other OSs. As a result, I'd like to make it part of the cabalized AES package. This works well enough with the pure-C variant of the implementation, but it also has assembly-based implementations of the core encryption routines for x86 and x86_64, specifically using yasm, which I would like to use when possible. So, two problems.. - First, I need to make cabal detect yasm's presence, and call out to it when appropriate. The former I can do with a configure script; the latter, I'm not quite sure how to do. Currently, cabal can only do C; basically, I'm looking for a way to let it use any language that can be compiled to .o files. - Second, having manually compiled the C/asm bits to .a and .so form, I did eventually get cabal to link (seemingly) correctly against it, but it then did not proceed to copy libaes.so into ~/.cabal/lib/AES/ I'm not sure how to make it do that, either. I suppose I'll have to use hooks, but I'd appreciate a little advice on how, exactly Well, I've put a snapshot of my current code at http://brage.info/~svein/aes/, so you can have a look. I'd really appreciate the help. -- Svein Ove Aas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: deepseq-1.0.0.0
Excerpts from Simon Marlow's message of Wed Nov 18 09:55:28 +0100 2009: On 17/11/2009 12:25, Nicolas Pouillard wrote: Excerpts from Simon Marlow's message of Tue Nov 17 12:00:21 +0100 2009: I've just uploaded deepseq-1.0.0.0 to Hackage Great! I'm wondering what is the need/purpose for DeepSeqIntegral and DeepSeqOrd? I don't actually know, they were previously NFDataIntegral and NFDataOrd respectively. Unless anyone can think of a reason to want these, I'll remove them. No one claimed for them, I think and are just useless, and thus confusing. Best regards, -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] FastCGI under Windows
Just to provide completion to this thread, I gave up on Haskell Windows web development after discovering that some important libraries like network-minihttp did not compile under Windows (and I could never get FastCGI to work properly either, although it did compile). I'm now developing using Fedora running in VirtualBox. It took several hours to get the Haskell Platform installed properly under the Fedora version I'll be deploying to (Fedora 9), but now everything seems fine, including FastCGI. Since my end goal is to deploy to Fedora 9 in any case, this seems a good solution. Kevin --- On Thu, 11/26/09, Michael Snoyman mich...@snoyman.com wrote: From: Michael Snoyman mich...@snoyman.com Subject: Re: [Haskell-cafe] FastCGI under Windows To: Kevin Jardine kevinjard...@yahoo.com Cc: haskell-cafe@haskell.org Date: Thursday, November 26, 2009, 12:36 PM You could try calling the program as CGI instead of FastCGI to try and pin down where the error is coming from. Also, you could run a FastCGI script in a different language (Perl?) and see if that works. I can't say, however, that I've even used FastCGI on Windows. Michael On Thu, Nov 26, 2009 at 9:55 AM, Kevin Jardine kevinjard...@yahoo.com wrote: Just to add more detail: I am running Apache 2.2.9. The message I mentioned appeared in the Apache error log file when running the sample Haskell FastCGI scripts under localhost with mod_fastcgi. I understand that there are some problems with mod_fastcgi and Apache 2.2.9, so I downloaded the Apache 2.2.9 version of mod_fcgid from here: http://www.apachelounge.com/download/ and tried that instead. I no longer get the error message I mentioned before, but instead get: [Thu Nov 26 08:44:30 2009] [warn] mod_fcgid: read timeout from pipe [Thu Nov 26 08:44:30 2009] [error] [client 127.0.0.1] Premature end of script headers: test2.fcgi Any suggestions? Kevin --- On Wed, 11/25/09, Kevin Jardine kevinjard...@yahoo.com wrote: From: Kevin Jardine kevinjard...@yahoo.com Subject: [Haskell-cafe] FastCGI under Windows To: haskell-cafe@haskell.org Date: Wednesday, November 25, 2009, 10:44 PM I'm attempting to get FastCGI working with Haskell under Windows XP. However, all the sample code I've tried always fails with: user error (FCGX_Accept_r failed with error code: -) unknown listenType (0) Has anyone seen this before? Any ideas on what I could try to get this to work? Kevin ___ 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
[Haskell-cafe] HWN This week
Hey folks, I'm at home this weekend, and the internet is somewhat dodgey, so I'm going to delay the special Thanksgiving episode of the HWN till sunday afternoon... I suppose the Turkey-coma isn't helping either, but I'll never admit it... /Joe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hoogle down
Now it's running again. Just out of curiosity, what was wrong? 2009/11/28 Neil Mitchell ndmitch...@gmail.com Hi Keith, Thanks for pointing this out. I've no idea why it's failing, but will check once I get home - unfortunately the machine I'm currently on doesn't permit me to ssh in and find out. Thanks, Neil On Sat, Nov 28, 2009 at 6:53 AM, Keith Sheppard keiths...@gmail.com wrote: hoogle is down for me: Internal Server Error Thanks Keith -- keithsheppard.name ___ 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 -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Partially applied functions
Hi cafe, Is such a thing possible, add :: Int - Int - Int add x y = x + y -- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8] -- an example usage of the list k = map (\ f - f 10 ) adds add3s = filter (?) adds -- add3s = [add 3, add 3] addEvens = filter (?) adds --addEvens = [add 8] I want to have functions in place of the ? signs. I guess one would need a way of extracting the applied value from a partially applied function (or totally, doesn't matter) I came across such a structure while designing an algotihm and used data structures to represent functions and solved the problem. But this doesn't seem very *cute* to me and requires some bolier-plate (if you have a lot of this structure everywhere) , that's why I am asking for your precious suggestions. Best, -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
Ozgur Akgun wrote: Hi cafe, Is such a thing possible, add :: Int - Int - Int add x y = x + y -- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8] -- an example usage of the list k = map (\ f - f 10 ) adds add3s = filter (?) adds -- add3s = [add 3, add 3] addEvens = filter (?) adds --addEvens = [add 8] I want to have functions in place of the ? signs. I guess one would need a way of extracting the applied value from a partially applied function (or totally, doesn't matter) Well, sure you can: add3s = filter (\f - f 0 == 3) adds addEvens = filter (\f - isEven $ f 0) adds This is only possible since there is that special property of the addition that (add a) 0 == a forall a, i.e. you can extract the first parameter back out of the partial applied function by passing 0 as a second parameter. It clearly depends on the function how much information about the parameters can be read from the result. -- Steffen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hoogle down
Hi, Yep, it's all back now. The problem was that the server had run out of disk space. Ian fixed it for now, but do let me know if it fails again. Thanks, Neil On Sat, Nov 28, 2009 at 2:54 PM, Ozgur Akgun ozgurak...@gmail.com wrote: Now it's running again. Just out of curiosity, what was wrong? 2009/11/28 Neil Mitchell ndmitch...@gmail.com Hi Keith, Thanks for pointing this out. I've no idea why it's failing, but will check once I get home - unfortunately the machine I'm currently on doesn't permit me to ssh in and find out. Thanks, Neil On Sat, Nov 28, 2009 at 6:53 AM, Keith Sheppard keiths...@gmail.com wrote: hoogle is down for me: Internal Server Error Thanks Keith -- keithsheppard.name ___ 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 -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Custom cabal languages (hooks?)
On Sat, 2009-11-28 at 14:47 +0100, Svein Ove Aas wrote: I'm currently working on a binding to Brian Gladman's C/assembler AES implementation. This code is sufficiently small that it makes little sense to create a separate C library for it; furthermore, it isn't typically packaged by the various linux distributions, never mind other OSs. As a result, I'd like to make it part of the cabalized AES package. This works well enough with the pure-C variant of the implementation, but it also has assembly-based implementations of the core encryption routines for x86 and x86_64, specifically using yasm, which I would like to use when possible. The simplest thing from the cabal pov would be to just include the asm inline into a .c file. So, two problems.. - First, I need to make cabal detect yasm's presence, and call out to it when appropriate. The former I can do with a configure script; That's the bit that's actually easy within a Setup.hs, no need for non-portable ./configure scripts. the latter, I'm not quite sure how to do. Currently, cabal can only do C; basically, I'm looking for a way to let it use any language that can be compiled to .o files. Right, there's no support for that in the Simple build system. You'd have to use the hooks. - Second, having manually compiled the C/asm bits to .a and .so form, I did eventually get cabal to link (seemingly) correctly against it, but it then did not proceed to copy libaes.so into ~/.cabal/lib/AES/ I'm not sure how to make it do that, either. I suppose I'll have to use hooks, but I'd appreciate a little advice on how, exactly Right, it's only expecting one library. You could either link the stuff into the same lib or add copying code in the copy hook. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
Sorry, no good. I don't want to guess the first paramater, I really want to access it. 2009/11/28 Steffen Schuldenzucker sschuldenzuc...@uni-bonn.de Ozgur Akgun wrote: Hi cafe, Is such a thing possible, add :: Int - Int - Int add x y = x + y -- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8] -- an example usage of the list k = map (\ f - f 10 ) adds add3s = filter (?) adds -- add3s = [add 3, add 3] addEvens = filter (?) adds --addEvens = [add 8] I want to have functions in place of the ? signs. I guess one would need a way of extracting the applied value from a partially applied function (or totally, doesn't matter) Well, sure you can: add3s = filter (\f - f 0 == 3) adds addEvens = filter (\f - isEven $ f 0) adds This is only possible since there is that special property of the addition that (add a) 0 == a forall a, i.e. you can extract the first parameter back out of the partial applied function by passing 0 as a second parameter. It clearly depends on the function how much information about the parameters can be read from the result. -- Steffen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
Answering my own question, one can achieve the goal via doing a lookup, if the number of possible parameters is limited. eg. assume add is a function which can only take Int's from [0..9]. Interestingly, my situation is exactly like this. I think I'll implement such a lookup. The question is still open though, if somebody has some magic to extract the prameter from an applied function... 2009/11/28 Ozgur Akgun ozgurak...@gmail.com Sorry, no good. I don't want to guess the first paramater, I really want to access it. 2009/11/28 Steffen Schuldenzucker sschuldenzuc...@uni-bonn.de Ozgur Akgun wrote: Hi cafe, Is such a thing possible, add :: Int - Int - Int add x y = x + y -- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8] -- an example usage of the list k = map (\ f - f 10 ) adds add3s = filter (?) adds -- add3s = [add 3, add 3] addEvens = filter (?) adds --addEvens = [add 8] I want to have functions in place of the ? signs. I guess one would need a way of extracting the applied value from a partially applied function (or totally, doesn't matter) Well, sure you can: add3s = filter (\f - f 0 == 3) adds addEvens = filter (\f - isEven $ f 0) adds This is only possible since there is that special property of the addition that (add a) 0 == a forall a, i.e. you can extract the first parameter back out of the partial applied function by passing 0 as a second parameter. It clearly depends on the function how much information about the parameters can be read from the result. -- Steffen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ozgur Akgun -- Ozgur Akgun ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
The question is still open though, if somebody has some magic to extract the prameter from an applied function... It isn't possible. Closest solution will be a list of pairs (function,arg) and a special apply function that takes those pairs and apply to function an argument and.them, apply something else. Then you can interleave (+) and (*) as a function. ;) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: deepseq-1.0.0.0
On 28/11/09 14:04, Nicolas Pouillard wrote: Excerpts from Simon Marlow's message of Wed Nov 18 09:55:28 +0100 2009: On 17/11/2009 12:25, Nicolas Pouillard wrote: Excerpts from Simon Marlow's message of Tue Nov 17 12:00:21 +0100 2009: I've just uploaded deepseq-1.0.0.0 to Hackage Great! I'm wondering what is the need/purpose for DeepSeqIntegral and DeepSeqOrd? I don't actually know, they were previously NFDataIntegral and NFDataOrd respectively. Unless anyone can think of a reason to want these, I'll remove them. No one claimed for them, I think and are just useless, and thus confusing. Already gone in deepseq-1.1.0.0, which also renamed DeepSeq back to NFData. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANN: NoSlow - Microbenchmarks for array libraries
On Fri, Nov 27, 2009 at 1:05 PM, Henning Thielemann lemm...@henning-thielemann.de wrote: I found that the dependency on Cairo and GTK originates from criterion. I have to build criterion with 'cabal install -f-chart criterion'. Unfortunately I cannot do 'cabal fetch criterion' in order to look into the cabal file, before the dependencies are resolved ... Really? If cabal fetch runs the build depsolver before trying to download a package, that seems like a bug. Have you reported it? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] cabal-install binary for FreeBSD
Hi all, I'm trying out NearlyFreeSpeech.net for hosting my Haskell apps. They use FreeBSD 7.2, but I can't get cabal-install to compile since it runs out of memory during the link phase. So far I haven't had trouble manually installing packages, but it would be nice to just do cabal install... Anyway, I don't have FreeBSD installed locally, and I was wondering if anyone out there might have a cabal binary for FreeBSD that they could send over. Thanks, Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
-- Here's a expansion of the ideas presented for tracking the argument used
-- to create a partially applied function:
--
-- Based on simple pairs
--
add :: Int - Int - Int
add x y = x + y
addr :: Int - (Int, Int - Int)
addr a = (a, add a)
-- a list of partially applied functions
adds = [addr 3, addr 5, addr 7, addr 3, addr 5, addr 8]
-- an example usage of the list
k = map (\ f - (snd f) 10 ) adds
-- filtering
add3s = filter (\ f - fst f == 3) adds
addEvens = filter (\f - even $ fst f) adds --addEvens = [add 8]
k3 = map (\ f - (snd f) 10) add3s
keven = map (\ f - (snd f) 10) addEvens
--
-- Generalized:
--
data TaggedPartial a b c = TAG a (b - c)
tag :: (a - b - c) - a - TaggedPartial a b c
tag f a = TAG a (f a)
-- create a tagged partially applied function
tap :: TaggedPartial a b c - b - c
tap (TAG _ f) b = f b
-- tagged partial function apply
ttest :: TaggedPartial a b c - (a - Bool) - Bool
ttest (TAG a _) f = f a
-- tagged tag test
tadds = [tag add 3, tag add 5, tag add 7, tag add 3, tag add 5, tag add 8]
tk = map (\ f - tap f 10) tadds
tadd3s = filter (\ f - ttest f (==3)) tadds
taddEvens = filter (\ f - ttest f even) tadds
tk3 = map (\ f - tap f 10) tadd3s
tkeven = map (\ f - tap f 10) taddEvens
--
-- The examples of map and filter usage, show that the arguments to
-- tap and ttest are awkwardly flipped. Hence:
--
pat :: b - TaggedPartial a b c - c
pat = flip tap
testt :: (a - Bool) - TaggedPartial a b c - Bool
testt = flip ttest
tk' = map (pat 10) tadds
tadd3s' = filter (testt (==3)) tadds
taddEvens' = filter (testt even) tadds
tk3' = map (pat 10) tadd3s'
tkeven' = map (pat 10) taddEvens'
{-
Mark Lentczner
http://www.ozonehouse.com/mark/
m...@glyphic.com
-}
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Re: [Haskell-cafe] cabal-install binary for FreeBSD
On Sat, 2009-11-28 at 19:39 +0200, Michael Snoyman wrote: Hi all, I'm trying out NearlyFreeSpeech.net for hosting my Haskell apps. They use FreeBSD 7.2, but I can't get cabal-install to compile since it runs out of memory during the link phase. So far I haven't had trouble manually installing packages, but it would be nice to just do cabal install... I expect you'll find the same thing happens if you link anything else. My suggestion is to rebuild ghc from source and disable the split objects feature. That feature reduces final binary sizes but it makes the linker work too hard (and use too much memory). On Gentoo we used to disable split objects on machines with less than 256Mb memory. And that was with GNU ld which has had some memory use improvements in recent years. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANN: NoSlow - Microbenchmarks for array libraries
On Sat, 2009-11-28 at 09:29 -0800, Bryan O'Sullivan wrote: On Fri, Nov 27, 2009 at 1:05 PM, Henning Thielemann lemm...@henning-thielemann.de wrote: I found that the dependency on Cairo and GTK originates from criterion. I have to build criterion with 'cabal install -f-chart criterion'. Unfortunately I cannot do 'cabal fetch criterion' in order to look into the cabal file, before the dependencies are resolved ... Really? If cabal fetch runs the build depsolver before trying to download a package, that seems like a bug. Have you reported it? It's not a bug, it's a feature! :-) Henning, you want cabal unpack so you can study the package contents. The fetch command is mainly so you can fetch packages and then install them when you're offline. You'd be jolly annoyed if it missed dependencies. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
Will the following do what you wish? add :: Int - Int - Int add x y = x + y addends = [3,5,7,3,5,8]::[Int] add3s :: [Int] - [Int - Int] add3s addends = map add (filter (3==) addends) k3 :: [Int] k3 = map (\ f - f 10 ) (add3s addends) -- Regards, Casey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] cabal-install binary for FreeBSD
On Sat, Nov 28, 2009 at 7:56 PM, Duncan Coutts duncan.cou...@googlemail.com wrote: On Sat, 2009-11-28 at 19:39 +0200, Michael Snoyman wrote: Hi all, I'm trying out NearlyFreeSpeech.net for hosting my Haskell apps. They use FreeBSD 7.2, but I can't get cabal-install to compile since it runs out of memory during the link phase. So far I haven't had trouble manually installing packages, but it would be nice to just do cabal install... I expect you'll find the same thing happens if you link anything else. My suggestion is to rebuild ghc from source and disable the split objects feature. That feature reduces final binary sizes but it makes the linker work too hard (and use too much memory). On Gentoo we used to disable split objects on machines with less than 256Mb memory. And that was with GNU ld which has had some memory use improvements in recent years. Duncan I agree that would be a good idea, but I'm not sure if I'll have a success on this host. I'll let you know. In any event, for the record, I got about 20 packages to compile, including getting my actual site up and running. It was tedious with cabal-install, but I got the job done. Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
Will the following do what you wish? add :: Int - Int - Int add x y = x + y addends = [3,5,7,3,5,8]::[Int] -- P for predicate addPs :: (Int - Bool) - [Int] - [Int - Int] addPs predicate addends = map add (filter predicate addends) kP :: [Int] kP = map (\ f - f 10 ) (addPs (3==) addends) -- Regards, Casey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANN: NoSlow - Microbenchmarks for array libraries
Duncan Coutts schrieb: On Sat, 2009-11-28 at 09:29 -0800, Bryan O'Sullivan wrote: On Fri, Nov 27, 2009 at 1:05 PM, Henning Thielemann lemm...@henning-thielemann.de wrote: I found that the dependency on Cairo and GTK originates from criterion. I have to build criterion with 'cabal install -f-chart criterion'. Unfortunately I cannot do 'cabal fetch criterion' in order to look into the cabal file, before the dependencies are resolved ... Really? If cabal fetch runs the build depsolver before trying to download a package, that seems like a bug. Have you reported it? It's not a bug, it's a feature! :-) Henning, you want cabal unpack so you can study the package contents. The fetch command is mainly so you can fetch packages and then install them when you're offline. You'd be jolly annoyed if it missed dependencies. I well see the benefits of the current behaviour of 'cabal fetch' and according to the name 'unpack' I didn't expect it could be the solution of my problem. Duncan has explained kindly the issue in: http://hackage.haskell.org/trac/hackage/ticket/612 http://hackage.haskell.org/trac/hackage/ticket/423 However I have still the problem, that once criterion is installed without gtk and cairo, then 'cabal install' still wants to download them when I install packages that import 'criterion'. :-( Bug or feature? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell] ANN: NoSlow - Microbenchmarks for array libraries
On Sat, 2009-11-28 at 20:13 +0100, Henning Thielemann wrote: However I have still the problem, that once criterion is installed without gtk and cairo, then 'cabal install' still wants to download them when I install packages that import 'criterion'. :-( Bug or feature? That's a problem with the cabal-install resolver. When configuring criterion it optimistically assumes that it will be able to install the optional dependencies. I've been working on an extra bottom-up pass for the resolver that will prune packages that cannot possibly be installed. That should help in this case and for the more common case of packages that need a particular version of base. In the mean time, a workaround would be to try: $ cabal install noslow criterion -f-chart --dry-run That should make it select criterion without the chart dep, and since the deps of criterion will then not change it should end up picking the installed instance of criterion rather than rebuilding it. Another thing that'd help here, but isn't implemented, is installed constraints. So that you could ask it commit to using the installed instance of criterion, rather than it having the option to rebuild (which in general it needs so it can get consistent deps). Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Partially applied functions
On Nov 28, 2009, at 12:01 , Ozgur Akgun wrote: Answering my own question, one can achieve the goal via doing a lookup, if the number of possible parameters is limited. eg. assume add is a function which can only take Int's from [0..9]. Interestingly, my situation is exactly like this. I think I'll implement such a lookup. The question is still open though, if somebody has some magic to extract the prameter from an applied function... You can't, because it's a chunk of machine code, not an AST that can be walked to pull out parameters. The solution is to convert it to the latter form (in the simplest case, a tuple is good enough; if you need something more complicated you'll have to define an actual AST datatype). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allb...@kf8nh.com system administrator [openafs,heimdal,too many hats] allb...@ece.cmu.edu electrical and computer engineering, carnegie mellon universityKF8NH PGP.sig Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskell in online contests
this is where I've gotten to. http://moonpatio.com/fastcgi/hpaste.fcgi/view?id=5120#a5120 strangely enough Ive gotten no speedup at all from the substitution cost UArray (though I had to make it Int, Int to deal with digits.). But still I wonder if there's something else I missed. Im really curious what lazyness you used to go from 60 to 1.6? I always thought lazyness was automatic and seq made strictness possible. thanks Vishnu On Sat, Nov 28, 2009 at 7:41 AM, Daniel Fischer daniel.is.fisc...@web.dewrote: Am Samstag 28 November 2009 02:04:31 schrieb Daniel Fischer: Make it distance orig new = f m n and no thunks need be written at all in this case. Cuts down running time by nearly half :) I think you could speed it up significantly by calculating the distance more lazily. Yup :D Timings here: Your last ByteString code: 128s That with corrected index calculation: 172s Correct indices and distance orig new = f m n instead of memf m n: 99s That and an array for the substitution cost: 64s String IO, substitution cost array and a suitably lazy break-early distance function: 1.7s That and a lazier surcharge function: 1.5s The same with ByteString IO: 1.4s Yes, I'd say that qualifies as a significant speedup. ___ 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] namespaces for values, types, and classes
On Fri, 2009-11-27 at 11:07 +0100, Sebastian Fischer wrote: We cannot write class Name a where ... instance Name Name where ... Yes! Very annoying. I want to be able to make a type that is the most general instance of a single-parameter type class. This is a useful OOish thing to do. For example: class Compiler c where getInstalledPackages :: c - ... compileModule:: c - ... instance Compiler GHC where ... instance Compiler NHC where ... and sometimes I want a list of compilers... newtype Compiler where Compiler :: Compiler c = c - Compiler deriving Compiler compilers :: [Compiler] compilers = [Compiler ghc, Compiler nhc] Does anyone know why types and values are in separate namespaces but classes and types are not? I think it's because you cannot currently distinguish them in module import/exports. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] control-monad-failure and mtl
Hello folks,
I took advantage of Thanksgiving weekend to port my application to use
Control.Monad.Failure, and learned (slightly painfully) that I still
needed to pick some mechanism to instantiate my failure monads as.
After the experience, I have three questions/comments:
1. Why isn't there an instance for Either in mtl? (There is one for
Transformers. The error message left me very puzzled there: the docs
clearly claimed the instance existed, and only a little source code
diving elucidated the situation.) Copying the instance declaration
from the transformers version seems to fix it.
2. I was having difficulty instantiating MonadFailure as an ErrorT
for an arbitrary monad. Here is an example:
{-# LANGUAGE PackageImports, FlexibleContexts #-}
import mtl Control.Monad.Error
import mtl Control.Monad.State
import Control.Monad.Failure
data MyError = MyError String
instance Error MyError where
strMsg = MyError
type MyMonad = ErrorT MyError (State Integer)
failureFunction :: MonadFailure MyError m = Integer - m Integer
failureFunction 0 = failure $ MyError Cannot use zero
failureFunction n = return (n - 1)
-- instantiate
monadicFunction :: MyMonad Integer
monadicFunction = failureFunction 23
Which results in the following error:
failure.hs:19:18:
No instance for (MonadFailure
MyError (ErrorT MyError (State Integer)))
arising from a use of `failureFunction' at failure.hs:19:18-35
Possible fix:
add an instance declaration for
(MonadFailure MyError (ErrorT MyError (State Integer)))
In the expression: failureFunction 23
In the definition of `monadicFunction':
monadicFunction = failureFunction 23
Which seems to contradict the documentation and source code, which states:
Instances: [...]
(Error e, Monad m) = MonadFailure e (ErrorT e m)
How do I misunderstand?
3. In a motivating example, one of the goals of MonadFailure is to let
us mix the error code of third-party modules into the generic failure mode.
Control.Monad.Failure appears to give the machinery for instantiating a generic
failure monad, but it doesn't have any facilities for the opposite direction:
that is, marshalling a specific error form into the generic error form. Am I
mistaken, and if not, would it be a welcome addition to the library?
Cheers,
Edward
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Re: [Haskell-cafe] Partially applied functions
It sounds as if you want to carry some state around for each partially applied function, I think that's in monad territory. A cardinal rule of functional programming is to create new data, whenever possible. -- Regards, Casey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Partially applied functions
You can pattern match on the right hand side of '|' in a list comprehension, since a list comprehension is just the list monad. add :: Int - Int - Int add x y = x + y -- a list of partially applied functions adds = [add 3, add 5, add 7, add 3, add 5, add 8] -- an example usage of the list kP num = map (\ f - f 10 ) (addPs num) -- add3s = filter (?) adds -- add3s = [add 3, add 3] -- addEvens = filter (?) adds --addEvens = [add 8] addPs num = [ x | x - adds, x 0 == num ] -- Regards, Casey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: implementing recursive let
Hi Ryan, first, to get this out of the way, you wrote: Also, your definition of Function seems to have problems with scoping; unless you intended to make a dynamically scoped language, No, absolutely not! In fact, the whole exercise has been born out of frustration with certain ad-hoc extensions to an already evil domain-specific (macro substitution) language -- the extension being to add dynamically scoped local variables; and the basic evilness to allow substitution to occur in variable names (similar to make) as a poor man's substitute for functional abstraction. This makes for extremely cryptic programs whose result is very hard to predict. My aim is to show that there is a better way. (Value - Eval Value) seems very likely to get evaluated in the context it is called in. Fortunately, this is not the case, as I explicitly capture the evironment at the definition site, ignoring the one at the call site: eval (Lam parm body) = do env - ask return $ Function (\val - local (\_ - M.insert parm val env) (eval body)) Now to the interesting part: Now the question is, what do you want to happen when given a malformed let expression? I am pretty sure that you need more complicated flow-control here in order to get the result. I believe you are on the right track with continuations. My problem is that I have never really become comfortable with continuations; just couldn't wrap my head around all the nested lambdas involved. Is there a nice tutorial (preferably one of those functional perls, I love them) that explains how CPS actually works to produce those wonderful effects, like jumping around, fixing evaluation order and whatnot? I tried to follow the recent explanations by Jacques Carette and Oleg Kiselyov on this list but I must admit that I understood nought. Here is a question; what should these expressions do? let y = x; x = 1 in y let y = x x; x = 1 in x let x = x in x The last one is quite telling; I can see three possible behaviors here: 1) Loop 2) return some simple undefined value 3) Give an error blackhole I will note that behavior (1) seems very difficult to achieve with your current monad stack; eval (Var x) terminates simply by looking up the value in the environment. I think you need to think hard about evaluation order and decide what you really want to happen. The simplest answer, if you want to stay with strict evaluation, is probably to only allow recursive *function* definitions. This way you can delay fully initializing the environment until after you've finished evaluating the functions themselves. Thanks, Ryan. This got me thinking about the right questions. I found out that what I really want is a mixture of lazy and strict evaluation: I want variable definitions in a let expression to be lazy, but application of functions to be strict. (I don't know whether this kind of mixture has been used before.) Thus let y = x; x = 1 in y should evaluate to 1 . I want the meaning of declarations on the same level to be independent of their relative order. This is a purely functional language, after all, so why should it matter in which order things are defined? let y = x x; x = 1 in x Here y is never used, so again this evaluates to 1 . let x = x in x This should loop (or maybe better detected as a failure i.e. backhole), but only if and when x is used, either in an application or as the final result of the program. (In the former case it doesn't make a difference whether x is used in function or in argument position.) *** Thinking about how to make it _explicit_ in my code that application is strict, whereas variables are lazy, I saw that this needs a change in the type of environments. It used to be a map from variable names to _values_, i.e. evaluated expressions. If I change this to a map from variable names to either thunks (i.e. unevaluated expressions) or (evaluated) values, then everything else falls smoothly into place; no need for mdo/mfix anymore, thus no need for fiddling with ErrorT internals to convince it that variable lookup always succeeds, and last not least all my examples behave as I expect them to do (see attached code). So, in a way I /have/ (finally) given up ;-) because variables are now (internally) mutable cells: when a variable is demanded (e.g. by an application) it gets mutated from thunk to value. Could as well revert to a Reader monad and use STRefs for efficiency. (Or maybe I will finally try to understand how to use continuations for stuff like this.) I have learned (at least) this: The problem with using the host language's lazyness for implementing lazyness in the defined language is that the former is not directly observable. Thus it works fine as long as you buy the whole package, i.e. either make sure that there can't be a failure, or else use not only the built-in evaluation order but also the built-in failure mode: error, pattern match failure, i.e. exceptions that can occur in
Re: [Haskell-cafe] namespaces for values, types, and classes
Does anyone know why types and values are in separate namespaces but classes and types are not? I think it's because you cannot currently distinguish them in module import/exports. Ah, good point. For constructors there is special syntax which allows to distinguish them in im/exports. Even if you have data One = Uno data Two = One | Two and you want to im/export only the constructor `One` but neither the type `One` nor the constructor `Two` you can write `Two(One)` to refer to it. So, my assumption that class names and type names always appear in different contexts was wrong when it comes to im/exports and there doesn't seem to be an easy way to fix that. Thank you for clarifying! Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hoogle server error again
Just tried to use Hoogle and got: 500 Internal Server Error Michael ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskell in online contests
vishnu wrote: I always thought lazyness was automatic and seq made strictness possible. Laziness is the default, but that doesn't mean it's everywhere. For example, every time you do pattern matching you enforce strictness: foo (x:xs) = 5 == foo _|_ == _|_ However, there's also a way to make patterns lazy: foo ~(x:xs) = 5 == foo _|_ == 5 The difference here is in how they're compiled/desugared, something like this: foo (x:xs) = 5 == foo = \xs' - case xs' of (x:xs) - 5 foo ~(x:xs) = 5 == foo = \xs' - let (x:xs) = xs' in 5 == foo = \xs' - 5 So writing the same function in different ways can enforce different strictness behavior. There are also more substantial algorithmic uses of laziness. One example is writing functions in a way that facilitates list fusion or on-line consumption of lists, vs writing functions in a way that forces more than one cell of the list at a time. Deforestation and garbage collection are not laziness, but appropriate uses of laziness can allow you to leverage them to improve the performance of your code. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghci breakpoints
Hello, I'm having trouble setting breakpoints from ghci. I load the files and I can tell things are working correctly because I can run the program and list the locations where I want to set breakpoints. E.g. Prelude :list Focus.focus 510 focus :: forall s m. Class s m = Neg - m [Foci] 511 focus f = 512 let ats = Path.atoms f But when I try to set a breakpoint I get Prelude :break Focus.focus No breakpoints found at that location. Does anyone have ideas about what I'm doing wrong in this case? Do I need to load with some special options to have breakpoints work? Thanks, Sean ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] haskell in online contests
vishnu wrote: wow ok, I'm not even able to see why they're different in the desugared version They're different because case is strict binding (see caveat below) whereas let is lazy binding. If we say, let foo = big ugly computation in bar Then if foo isn't used in bar, it'll never be computed. (Even if foo occurs in bar, provided it occurs somewhere that won't be evaluated.) Whereas if we say, case big ugly computation of foo - bar Then we're forced to do the computation, regardless of whether foo is used in bar. Actually, that's not entirely true. In this example, because foo is a variable, the binding will be lazy; whereas if we replaced foo with a (non-lazy) pattern then it'd be strict. Part of the complication in explaining the exact details is because both case and let can have patterns inside of the binding so the desugaring process has to continue recursively. Also there're some details about using let for defining recursive groups, which you can't do with case. Also Haskell's syntax conflates defining functions with doing pattern matching, so there's an extra step to separate functions using pattern matching into the definition binding vs the pattern matching. In any case, once you're done compiling you end up with a strict binding operator (kind of like case) and a lazy binding operator (kind of like let). When in doubt, try playing around with different definitions to see whether they break when you pass in 'undefined'. There are also a few papers out there on how the STG works under the covers. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANNOUNCE: Clutterhs 0.1
On Sat, 28 Nov 2009 23:18:00 -0500 Matt == Matt Arsenault arse...@rpi.edu wrote: Hi Matt, Matt This is a very early announcement for an initial release of Matt bindings for Clutter 1.0, now on Matt Hackage,http://hackage.haskell.org/package/clutterhs Thanks a lot for this project. I'm just thinking about using Haskell on Moblin OS. ;) Matt It uses c2hs, and depends on gtk2hs from darcs for the Matt glib/gobject bindings. Overall, its usage should be similar to Matt gtk2hs. This is very cool. Matt This is my first Haskell project, and suggestions on the API, bug Matt reports, etc. are appreciated. What do you think about binding Moblin's nbtk (now it's called mx) ? Otoh, are you aware of: http://github.com/elliottt/clutter http://github.com/yav/clutter Sincerely, Gour -- Gour | Hlapicina, Croatia | GPG key: F96FF5F6 signature.asc Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
