Re: [Haskell-cafe] Idea for a tool
On Wed, Oct 20, 2010 at 7:36 AM, Michael Snoyman mich...@snoyman.com wrote: Hi all, I saw a quote from Eric Kow via Neil Mitchell[1] that we don't spend enough time writing tools. Well, I've decided that the most annoying part of package maintainership right now is staying on top of new versions of dependencies. We essentially have two options right now: * Follow the PVP and put an upper bound on all dependencies, and people will be upset when your package only works with the old version of the dependency. * Skip the upper bound, and risk having your code break when there's a new version. I have an idea for a tool: you give it a list of packages you maintain, or even better yet, you give it your email address and it gets that list automatically. Then is looks through all your dependencies and sees if you have any upper bounds preventing newer versions from being used. Bonus points for making it a web service that just gives you an RSS feed. If anyone's interested in writing a tool like that, let me know. Otherwise, next time I'm twiddling my thumbs I'll try to throw it together. I've never dealt directly with the Cabal library, but there's a first time for everything. If someone else wants to write that tool and wants help sticking a web service on it, let me know. Michael [1] http://neilmitchell.blogspot.com/2010/10/enhanced-cabal-sdist.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe This would be a nice feature for the new hackage server: http://sparky.haskell.org:8080 Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to make cabal pass flags to happy?
Thanks for the answers, all. :-) Since this doesn't seem to be the common knowledge I expected it to be, I'll try to work out how it's done properly and blog about it. And hopefully generate some much needed documentation for cabal along the way. What I want specifically is to have happy produce a GLR parser from my .ly file, and I want this to happen during 'cabal install'. Which in turn means I want cabal to pass the --glr flag to happy during setup. My best guess is that I might want to use 'ppHappy' [1], or something in the vicinity, but there's no documentation for the combinator and it's far from obvious how to pass arguments to it. I think the right solution is for the happy source file to specify what kind of grammar it is / should be produced. Yes, that would mean modifying happy. Hmm, I agree with you in this particular case, regarding the grammar, since it really only makes sense for any given happy grammar to generate either kind of parser. But such a solution still wouldn't answer the general question about passing flags to preprocessors. Certainly not all such use cases are best fixed by pushing the flags into the pre-processed files. Cheers, /Niklas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: libefence useful for debugging ghc+ffi programs?
That looks a lot like a double free [...] there's definitely something about initializing libcurl: http://curl.haxx.se/libcurl/c/curl_easy_init.html uses nice phrases like may be letal in multi-threading the documentation of Haskell curl http://hackage.haskell.org/packages/archive/curl/1.3.5/doc/html/Network- Curl.html just says withCurlDo should be called once while in fact it should be much stronger: must be called exactly once? anyway I temporarily dropped curl (replaced by system wget ) and the erratic behaviour persists. Now it looks like this: Electric Fence 2.1 Copyright (C) 1987-1998 Bruce Perens. [New Thread 0x7fc37b70f6e0 (LWP 7281)] [New Thread 0x4122a950 (LWP 7284)] [New Thread 0x4214a950 (LWP 7285)] Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fc37b70f6e0 (LWP 7281)] 0x7fc37b715aae in memalign () from /usr/lib/libefence.so.0 (gdb) where #0 0x7fc37b715aae in memalign () from /usr/lib/libefence.so.0 #1 0x7fc37b715c97 in malloc () from /usr/lib/libefence.so.0 #2 0x7fc37a492a55 in gethostbyname () from /lib/libc.so.6 #3 0x0089cc88 in networkzm2zi2zi1zi7_NetworkziBSD_zdwlvl_info () #4 0x in ?? () and indeed, gethostbyname is famous for being non re-entrant. (packages I use are HTTP, hxt, happstack-server; and I can't drop all of them ...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Idea for a tool
Hi Michael, I want this tool. I fake it slightly by using my RSS reader and http://page2rss.com/ to get notified when any packages I depend on change, which basically works - but if you could provide a better service (ideally integrated in to hackage), I'd use it. Thanks, Neil On Wed, Oct 20, 2010 at 8:27 AM, Bas van Dijk v.dijk@gmail.com wrote: On Wed, Oct 20, 2010 at 7:36 AM, Michael Snoyman mich...@snoyman.com wrote: Hi all, I saw a quote from Eric Kow via Neil Mitchell[1] that we don't spend enough time writing tools. Well, I've decided that the most annoying part of package maintainership right now is staying on top of new versions of dependencies. We essentially have two options right now: * Follow the PVP and put an upper bound on all dependencies, and people will be upset when your package only works with the old version of the dependency. * Skip the upper bound, and risk having your code break when there's a new version. I have an idea for a tool: you give it a list of packages you maintain, or even better yet, you give it your email address and it gets that list automatically. Then is looks through all your dependencies and sees if you have any upper bounds preventing newer versions from being used. Bonus points for making it a web service that just gives you an RSS feed. If anyone's interested in writing a tool like that, let me know. Otherwise, next time I'm twiddling my thumbs I'll try to throw it together. I've never dealt directly with the Cabal library, but there's a first time for everything. If someone else wants to write that tool and wants help sticking a web service on it, let me know. Michael [1] http://neilmitchell.blogspot.com/2010/10/enhanced-cabal-sdist.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe This would be a nice feature for the new hackage server: http://sparky.haskell.org:8080 Bas ___ 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] Idea for a tool
Well, here's an initial, ugly version of this tool. Feed it two command line arguments: a cabal file, and the 00-index.tar file in the .cabal/packages/hackage.haskell.org folder. More work to follow. Michael On Wed, Oct 20, 2010 at 12:25 PM, Neil Mitchell ndmitch...@gmail.com wrote: Hi Michael, I want this tool. I fake it slightly by using my RSS reader and http://page2rss.com/ to get notified when any packages I depend on change, which basically works - but if you could provide a better service (ideally integrated in to hackage), I'd use it. Thanks, Neil On Wed, Oct 20, 2010 at 8:27 AM, Bas van Dijk v.dijk@gmail.com wrote: On Wed, Oct 20, 2010 at 7:36 AM, Michael Snoyman mich...@snoyman.com wrote: Hi all, I saw a quote from Eric Kow via Neil Mitchell[1] that we don't spend enough time writing tools. Well, I've decided that the most annoying part of package maintainership right now is staying on top of new versions of dependencies. We essentially have two options right now: * Follow the PVP and put an upper bound on all dependencies, and people will be upset when your package only works with the old version of the dependency. * Skip the upper bound, and risk having your code break when there's a new version. I have an idea for a tool: you give it a list of packages you maintain, or even better yet, you give it your email address and it gets that list automatically. Then is looks through all your dependencies and sees if you have any upper bounds preventing newer versions from being used. Bonus points for making it a web service that just gives you an RSS feed. If anyone's interested in writing a tool like that, let me know. Otherwise, next time I'm twiddling my thumbs I'll try to throw it together. I've never dealt directly with the Cabal library, but there's a first time for everything. If someone else wants to write that tool and wants help sticking a web service on it, let me know. Michael [1] http://neilmitchell.blogspot.com/2010/10/enhanced-cabal-sdist.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe This would be a nice feature for the new hackage server: http://sparky.haskell.org:8080 Bas ___ 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] Haskellers.com skills list moderation?
My $.02 follows: From: Michael Snoyman mich...@snoyman.com There's only two skills which I think absolutely must go: Other languages I know: C# .NET, XSLT, Microsoft SQL Server, XML, SQL, CSS, C, C++, Java, HTML, Visual Basic Script, Pascal, Rexx, Basic and assembler tool building Agreed that both should go. There are 11 skills I'm leaning towards dropping, all because they fall in the too vague/too general category. Your input is requested on these. They are: Attribute Grammar Keep as Attribute Grammars Cabal, packaging, build and distribution tools This should be two categories: Cabal internals and Software packaging/distribution tools. Keep Cabal internals, possibly keep the other Categorical Programming Denotational design Digital Forensics keep Fault Tolerant Server Software Mathematics drop (possibly keep FTSS, maybe change the name) Programming using Arrows Possibly keep with a different name Proving observational equivalence between Haskell programs drop Transactional business applications development I'm not entirely sure what this means, specifically if it's business transactions or db/software transactions. UNIX Scripting and Tool Authoring keep as UNIX Scripting Of the remaining 32 skills, some of them fall in the too specific range just a bit (software transactional memory, property based testing), but I'm inclined to let it slide. These 32 are: Advanced type-level programming (GADTs, TypeFamilies, proofs, etc.) Algorithmic Problem Solving Bioinformatics Concurrent Haskell DSL Design Darcs internals Foreign Function Interface (FFI) Formal Verification Functional graphics programming (2D, 3D, GPU) GHC internals Generic Programming Graphical User Interfaces Happstack Web Framework Hardware Acceleration DSLs Haskell on embedded devices High Assurance Software Development High-performance Haskell Metaprogamming via Template Haskell Natural Language Processing (tagging, parsing, translation,...) Physics Simulation Programming language translation Property based testing (QuickCheck) Purely functional data structures — design and implementation Reverse Engineering Robotics and Automation Signal Processing Software Transactional Memory Teaching Haskell Web development (HTML, CSS and Javascript) Yesod Web Framework I would argue for keeping most of these. I do think that skills based on specific packages (Happstack, Yesod, STM?) perhaps should be dropped, except for packages that are integral to the Haskell universe (compilers, Cabal, Darcs?, QuickCheck?). For these packages, I think the -internals categories are the most useful. What about rolling Happstack, Yesod, etc. into Haskell Web Frameworks, and possibly also keeping the Web Development (HTML, CSS and Javascript) category? John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HDBC/ODBC/MySQL - working configuration?
Hi I'm having some difficulty getting the above combination to work, I've successfully used ODBC against MS but the MySQL stuff is creating some really interesting error conditions in the HDBC-ODBC module. My first thought is that it must be me, so does anyone out there have this combination working (with or without HaskellDB)? If so, can you tell me which versions of things you are using and which ODBC drivers (and configurations) you are using? Cheers Neil___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellers.com skills list moderation?
On 20 October 2010 21:38, John Lato jwl...@gmail.com wrote: Cabal, packaging, build and distribution tools This should be two categories: Cabal internals and Software packaging/distribution tools. Keep Cabal internals, possibly keep the other What does Cabal internals refer to? Actually using Cabal as a library? Developing Cabal itself? Fault Tolerant Server Software Mathematics drop (possibly keep FTSS, maybe change the name) Why drop mathematics? (I'd prefer it to be split up, but mathematically-oriented programming is a large/important subset of Haskell skills IMHO, though I admit I'm biased). UNIX Scripting and Tool Authoring keep as UNIX Scripting What's wrong with Tool Authoring? To some, scripting implies quick+dirty temporary applications/scripts as opposed to a well-engineered tool. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellers.com skills list moderation?
On 20 October 2010 21:52, Henning Thielemann lemm...@henning-thielemann.de wrote: On Wed, 20 Oct 2010, John Lato wrote: Mathematics I'd be interested in how many Haskellers refer to Category Theory here, and how many to other mathematical subjects. :-) I for one refer to other stuff; my understanding of CT is almost non-existant. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Are newtypes optimised and how much?
| At the end of the day what motivated me to ask these questions it that
| I like very much defining newtypes for most of the types I use, I have
| completely forgotten about `type' aliasing. I'm completely happy to
| write Foo and unFoo all over the place to aid my type correctness, but
| I want a nice generic way to convert to/from newtypes but keeping it a
| compile-time concept. Sometimes I have unThisThat, unTheOther,
| unThoseWhoShantBeNamed, etc. and it I could just use fromIntegral and
| fromString then that would be super.
Yes, you can freely use Foo/unFoo. There's no runtime penalty. (In the jargon
of GHC's intermediate language, Foo and unFoo translate to *type-safe casts*,
which generate no executable code.
That includes the 'newtype deriving' stuff too, and hence your uses of
fromInteger etc.
However, sadly:
| Also, is 'map unFoo' optimised away at compile-time, too? I think that
| it would be compiled to map id. So it would still wrap a thunk around
| each cons. How far does it go?
No, this isn't optimised. The trouble is that you write (map Foo xs), but GHC
doesn't know about 'map'. We could add a special case for map, but then you'd
soon want (mapTree Foo my_tree).
What you really want is to say is something like this. Suppose my_tree :: Tree
String. Then you'd like to say
my_tree ::: Tree Foo
meaning please find a way to convert m_tree to type (Tree Foo), using newtype
coercions.
The exact syntax is a problem (as usual). We have the technology now. The
question is how important it is.
Simon
| -Original Message-
| From: haskell-cafe-boun...@haskell.org
[mailto:haskell-cafe-boun...@haskell.org]
| On Behalf Of Christopher Done
| Sent: 19 October 2010 19:12
| To: Haskell Cafe
| Subject: [Haskell-cafe] Are newtypes optimised and how much?
|
| So I have the following nice things:
|
| {-# LANGUAGE GeneralizedNewtypeDeriving, OverloadedStrings #-}
|
| import Data.String
|
| newtype Foo = Foo { unFoo :: String } deriving (IsString)
|
| x :: Foo
| x = Hello, World!
|
| newtype Bar = Bar { unBar :: Integer } deriving
| (Eq,Show,Num,Integral,Real,Enum,Ord)
|
| y :: Bar
| y = 2
|
| I can write literals and they will be converted to the type I wanted
| with no extra verbiage needed.
|
| Questions (I'm talking about GHC when I refer to compilation):
|
| (1) Are fromString and fromIntegral ran at compile time? I don't think
| that this is the case. I think they are just translated to fromString
| Hello, World! and fromIntegral 2 verbatim.
| (2) Regardless of this, the implementation of fromString and
| fromIntegral is essentially a no-op, it's just fromString = Foo,
| fromIntegral = Bar, which is in turn essentially fromString = id,
| fromIntegral = id, as far as I understand it. It's purely compile
| time. But supposing I write:
|
| fromIntegral (fromIntegral (2::Integer) :: Bar) :: Integer
|
| Is this at the end of the day equal to just (2::Integer)? Thinking
| simple-mindedly, I would say, yes. The compiler knows that
| fromIntegral :: Integer - Bar == id, and that fromIntegral :: Bar -
| Integer == id (right?). But is that the case? Perhaps the type class
| methods have some dictionary and thus cannot be inlined, or maybe that
| doesn't matter?
|
| At the end of the day what motivated me to ask these questions it that
| I like very much defining newtypes for most of the types I use, I have
| completely forgotten about `type' aliasing. I'm completely happy to
| write Foo and unFoo all over the place to aid my type correctness, but
| I want a nice generic way to convert to/from newtypes but keeping it a
| compile-time concept. Sometimes I have unThisThat, unTheOther,
| unThoseWhoShantBeNamed, etc. and it I could just use fromIntegral and
| fromString then that would be super.
|
| Also, is 'map unFoo' optimised away at compile-time, too? I think that
| it would be compiled to map id. So it would still wrap a thunk around
| each cons. How far does it go?
|
| So, if I go around using fromIntegral/fromString (etc. for other
| newtype types), is it still kept compile time? After having newtypes
| catch dozens of type mismatches that otherwise wouldn't unified
| happily but were completely wrong (e.g. wrong argument order), I've
| found newtype to be an indispensable part of Haskell and of writing a
| large piece of software.
|
| Cheers
| ___
| Haskell-Cafe mailing list
| Haskell-Cafe@haskell.org
| http://www.haskell.org/mailman/listinfo/haskell-cafe
___
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Re: [Haskell-cafe] Haskellers.com skills list moderation?
On Wed, Oct 20, 2010 at 11:48 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 20 October 2010 21:38, John Lato jwl...@gmail.com wrote: Cabal, packaging, build and distribution tools This should be two categories: Cabal internals and Software packaging/distribution tools. Keep Cabal internals, possibly keep the other What does Cabal internals refer to? Actually using Cabal as a library? Developing Cabal itself? Developing Cabal itself. Fault Tolerant Server Software Mathematics drop (possibly keep FTSS, maybe change the name) Why drop mathematics? (I'd prefer it to be split up, but mathematically-oriented programming is a large/important subset of Haskell skills IMHO, though I admit I'm biased). Mathematics is far too broad to be useful. I agree that subsets of math would be informative (e.g. statistical modelling, linear algebra, graph theory, dif. eq., etc.), but how do you break up Mathematics and assign users who listed it as a skill to its constituent parts? UNIX Scripting and Tool Authoring keep as UNIX Scripting What's wrong with Tool Authoring? To some, scripting implies quick+dirty temporary applications/scripts as opposed to a well-engineered tool. Again, Tool Authoring is too broad to be useful. What else do software developers do but author tools? Contrast to UNIX Scripting, which means familiarity with at least a shell and likely one or more of awk, perl, python, regexes, ... I don't make quality judgements just from the term scripting, and I'd certainly rather use a well-engineered script over a quick+dirty tool. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellers.com skills list moderation?
On 20 October 2010 12:30, John Lato jwl...@gmail.com wrote: [SNIP] Again, Tool Authoring is too broad to be useful. Who are the skills lists for? Recruiters, other Haskellers to form strike forces, something else? For the recruiters I think they are somewhat obscure unless Well-Typed or Galois were searching. Trivia - I did once apply for a job that listed 'attribute grammars' as a requirement - as far as I could tell it was compiler development / maintenance for a special purpose chip, but I never heard back so I guess I missed the mark on the other skills. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellers.com skills list moderation?
On Tue, Oct 19, 2010 at 2:32 PM, Michael Snoyman mich...@snoyman.com wrote: Algorithmic Problem Solving I think this needs to go, because I'm really having a hard time imagining any programmer who doesn't do this. High Assurance Software Development This sounds vague to me and/or the same as other skills (cf. Formal Verification). Again, I'm not sure how many people would describe their software as low assurance. Robotics and Automation Would be tempted to drop Automation from here. Web development (HTML, CSS and Javascript) I wonder if these parentheses are necessary, or if they hint at the fact that this isn't really one skill. I have a suspicion that being competent at website and stylesheet *design* (i.e. knowledge of good design principles and application to HTML/CSS) is an entirely different sort of thing from *implementation* in terms of JavaScript technologies like AJAX and JSON and who-knows-what. Overall, I think it would be nice to have a consistent idea about how concrete or abstract we allow skills to be, and as someone else mentioned what the target audience is for them. We have skills that relate to specific libraries and then skills that are nebulous and abstract. Maybe we could ask a narrower question, or have two fields: what can you use, and what interests you. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Idea for a tool
Alright, the tool is up and incredibly basic right now. Go to: http://packdeps.haskellers.com/, type a search string, and hit enter. The site will filter through all of the cabal files for the most recent releases of each package and select the ones where your search string appears in the package name, maintainer and/or author fields. From those packages, it will check to see if there are any upper-bounds restrictions excluding a package. The results are returned as an Atom feed, so you can easily add this to a reader or maybe even sign up for email alerts[1]. Let me know if there are any bugs, eventually I'll put up some proper information on the page describing what's going on there. Oh, and the package database gets refreshed every 6 hours. Michael [1] http://www.feedmyinbox.com/ On Wed, Oct 20, 2010 at 12:30 PM, Michael Snoyman mich...@snoyman.com wrote: Well, here's an initial, ugly version of this tool. Feed it two command line arguments: a cabal file, and the 00-index.tar file in the .cabal/packages/hackage.haskell.org folder. More work to follow. Michael On Wed, Oct 20, 2010 at 12:25 PM, Neil Mitchell ndmitch...@gmail.com wrote: Hi Michael, I want this tool. I fake it slightly by using my RSS reader and http://page2rss.com/ to get notified when any packages I depend on change, which basically works - but if you could provide a better service (ideally integrated in to hackage), I'd use it. Thanks, Neil On Wed, Oct 20, 2010 at 8:27 AM, Bas van Dijk v.dijk@gmail.com wrote: On Wed, Oct 20, 2010 at 7:36 AM, Michael Snoyman mich...@snoyman.com wrote: Hi all, I saw a quote from Eric Kow via Neil Mitchell[1] that we don't spend enough time writing tools. Well, I've decided that the most annoying part of package maintainership right now is staying on top of new versions of dependencies. We essentially have two options right now: * Follow the PVP and put an upper bound on all dependencies, and people will be upset when your package only works with the old version of the dependency. * Skip the upper bound, and risk having your code break when there's a new version. I have an idea for a tool: you give it a list of packages you maintain, or even better yet, you give it your email address and it gets that list automatically. Then is looks through all your dependencies and sees if you have any upper bounds preventing newer versions from being used. Bonus points for making it a web service that just gives you an RSS feed. If anyone's interested in writing a tool like that, let me know. Otherwise, next time I'm twiddling my thumbs I'll try to throw it together. I've never dealt directly with the Cabal library, but there's a first time for everything. If someone else wants to write that tool and wants help sticking a web service on it, let me know. Michael [1] http://neilmitchell.blogspot.com/2010/10/enhanced-cabal-sdist.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe This would be a nice feature for the new hackage server: http://sparky.haskell.org:8080 Bas ___ 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] Haskellers.com skills list moderation?
On Wed, Oct 20, 2010 at 9:02 AM, Ben Millwood hask...@benmachine.co.uk wrote: Robotics and Automation Would be tempted to drop Automation from here. That name was deliberately chosen, and is appropriate for people in the area, http://www.ieee-ras.org/ I have my own opinions on a lot of these tags, but haskell-cafe doesn't seem like the right forum for this polling. A difficulty is that while we may all be qualified to debate the merits of Mathematics as a discriminative label for programmers, some of these tags (such as the one above) are domain specific. We don't want people outside of an area of interest governing name choices that lessen the value of the tags. As a strawman for people to beat up on, what if each tag linked to a wiki description? Such a description could include a couple sentences of exposition, and perhaps links to relevant resources. Another alternate is that if a tag becomes *too* popular (i.e. more than x% of haskellers check it off), then perhaps there should be a poll to have it removed and its spirit embedded in the general site text. Tags like Algorithmic Problem Solving might fall into this category. Anthony ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskellers.com skills list moderation?
I just want to throw out 2 extreme case solutions to think about while this problem doesn't really seem to be heading anywhere: 1) Drop the skills options in favor of the simple text box already in use. This would of course would have a big impact on attempting to search for haskellers. 2) A formal Haskell certification system that would be of great use outside of haskellers.com too and recognized and trusted by employers all over the world. Java developers can certifiably in individual areas through thishttp://en.wikipedia.org/wiki/Sun_Certified_Professionalfor example. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Should Yesod.Mail be a separate package?
Michael Snoyman wrote: [1] http://hackage.haskell.org/package/mime-mail Great news! This is an important package. It's obviously very preliminary, though. This is not trivial to get right - look at the long and colorful history of the Python email library, detailed on the first page of the library documentation. Here are some initial suggestions for improvement: 1. The module name Network.Mail.Mime is too generic. There will also be a parser someday. We should have Types, Parse, and Render in separate modules. I expect each of those to grow gradually as more features are added. On the other hand, I think I like the decision to re-implement just the features of RFC 2822 message format needed for everyday MIME use rather than building this on top of a more generic message type, as is done in Python. It simplifies things. But are multi-line headers supported properly? That's trickier than it looks, there have historically been many wrong implementations out there. That itself could be a reason to build this on top of a proper RFC 2822 implementation. 2. mailHeaders should have an Ord instance that compares case-insensitively, though the underlying Strings should remain Strings. 3. It should be possible to control whether text parts get quoted-printable encoded. Perhaps add QuotedPrintable to Encoding? 4. I don't like having those sendmail things here in the same module and package. It's convenient, but messy in several ways - creates a spurious dependency on process, only works on certain platforms and even then with possible weird platform dependencies, etc. I think this should be in a separate package. Once there is a nice easy-to-use SMTP companion package, I don't think the sendmail things will be used that much anyway. Put them in a separate package, but mention it in prominent places so people will find it. 5. Is the blaze-builder dependency necessary now that Bryan has built those techniques into Data.Text? 6. Are I18N text-encoded headers supported? That's very important, even for simple everyday usage. It's a bit complicated, though. That might be another reason to build on top of a full RFC 2822 implementation. 7. This very simple interface is great for everyday use. Think about how to add the less common options for more general use, without cluttering up the everyday interface - custom parameters for Content-Type and Content-Disposition, specifying the boundary rather than allowing it to be generated automatically, etc. It's important to think about those kinds of things now, before the interface gets set in cement. Thanks, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fountain-0.0.0
2 things. 1. Wow that's cool. 2. Is this technology not patented by Digital Fountain? (now Qualcomm?) I remember when I first heard of fountain codecs, I thought it was science fiction based on the description :-). Dave On Tue, Oct 19, 2010 at 8:00 PM, Tom Hawkins tomahawk...@gmail.com wrote: This library [1] implements a fountain code [2]. Fountain codes are forward error correction codes for erasure channels [3]. A fountain code encodes a message into an infinite stream of packets -- transmitters generate message packets at random, on-the-fly. To reconstruct the message, receivers simply need to capture enough packets for the decoding process. As a rateless code, fountain codes automatically adapt to varying channel conditions. Some of the more interesting applications of fountain codes include unsynchronized data broadcast and distributed download. For example, a multiple number of devices can transmitting content to multiple receivers without any coordination. Because packets are generated at random, receivers increase their bandwidth simply by listening to more transmitters. Note that receivers can also start generating packets and forwarding the message on even before they have decoded the complete message. This library provides a packet generator and a decoder for one of the first known fountain codes: LT codes [4]. It also includes a test function to experiment with message lengths, and encoding degrees -- it runs a simulation to determine the number of packets needed to decode a message. -Tom [1] http://hackage.haskell.org/package/fountain [2] http://en.wikipedia.org/wiki/Fountain_code [3] http://en.wikipedia.org/wiki/Binary_erasure_channel [4] http://en.wikipedia.org/wiki/LT_codes ___ 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] Haskellers.com skills list moderation?
On 10/20/10 9:12 AM, Anthony Cowley wrote: We don't want people outside of an area of interest governing name choices that lessen the value of the tags. To be honest, when the thread first came up, I was afraid NLP (or AG) would end up on the cutting block because of that... As a strawman for people to beat up on, what if each tag linked to a wiki description? Such a description could include a couple sentences of exposition, and perhaps links to relevant resources. +1. As an additional strawman, perhaps the I can use X (package, program, markup language,...) stuff should be broken out separately from the skills, just like package authorship is. There seems to be a tension here between resume-esque listing of every competence with some acronym-of-the-day, vs listing larger areas of overall knowledge (NLP, RA, mathematics,...) Another alternate is that if a tag becomes *too* popular (i.e. more than x% of haskellers check it off), then perhaps there should be a poll to have it removed and its spirit embedded in the general site text. Tags like Algorithmic Problem Solving might fall into this category. +1. Another option which may be interesting to pursue is to make the skills list hierarchical, so that when Algorithmic Problem Solving gets broken up into Foo, Bar, and Zot, we get the new skills listed as checkable subskills of uncheckable Algorithmic Problem Solving. ...Though that might just be delaying the garbage collection until later (witness Data.*). -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fountain-0.0.0
1. Wow that's cool. Indeed. 2. Is this technology not patented by Digital Fountain? (now Qualcomm?) I'm sure it is. This library is a naive implementation of LT codes, which have nowhere near the performance of Digital Fountain's Raptor codes. I remember when I first heard of fountain codecs, I thought it was science fiction based on the description :-). What I find amazing is RaptorQ fountain codes can complete the decoding after receiving only 1% more symbols than the original message. -Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
On 20 October 2010 13:09, Simon Peyton-Jones simo...@microsoft.com wrote:
Yes, you can freely use Foo/unFoo. There's no runtime penalty. (In the
jargon of GHC's intermediate language, Foo and unFoo translate to *type-safe
casts*, which generate no executable code.
That includes the 'newtype deriving' stuff too, and hence your uses of
fromInteger etc.
Oh wow, excellent!
No, this isn't optimised. The trouble is that you write (map Foo xs), but
GHC doesn't know about 'map'. We could add a special case for map, but then
you'd soon want (mapTree Foo my_tree).
What you really want is to say is something like this. Suppose my_tree ::
Tree String. Then you'd like to say
my_tree ::: Tree Foo
meaning please find a way to convert m_tree to type (Tree Foo), using
newtype coercions.
The exact syntax is a problem (as usual). We have the technology now. The
question is how important it is.
I don't know whether it's so important for me at least. I was just
interested in how much optimisation it did.
On 20 October 2010 17:58, Gregory Crosswhite gcr...@phys.washington.edu wrote:
On 10/20/10 4:09 AM, Simon Peyton-Jones wrote:
No, this isn't optimised. The trouble is that you write (map Foo xs), but
GHC doesn't know about 'map'. We could add a special case for map, but then
you'd soon want (mapTree Foo my_tree).
How about a special case for fmap? That seems like it should handle a lot
of cases.
Personally I haven't had much use for mapping newtype
constructors/unconstructors.
My personal use case of newtypes unwrapping/wrapping is in passing
them to functions and in record fields, not so much unwarpping them
inside data types and trees across the board.
-- | Assign a review for a submission to a user.
assignReview :: TrackId - UserId - SubmissionId - Model ()
assignReview tid uid sid = do
insert T.review $
F.uid- unUserId uid
# F.submission - unSubmissionId sid
# F.trackId- unTrackId tid
This is the simplest function I could find. However, consider if in my
busy hacking I accidentally get the argument order incorrect in the
definition, or the call, with newtypes I can't mismatch them. This has
stopped me doing bad things a few times in my haste.
Another nice thing I've found is combining them with view patterns:
-- | Submit a review.
submitReview :: UserId - SubmissionId - [ReviewField] - Model ()
submitReview (unUserId - uid) (unSubmissionId - sid) rs = do
forM_ rs $ \ReviewField{..} -
...
The next ten lines or so use uid and sid. This makes the submitReview
function kind of guarded from being given the wrong values. Inside
it can do what it wants. You might point out that now that I've
unwrapped them I can pass them to some other function willy nilly, but
of course if a function needs a submission id, then it needs a
SubmissionId. So I find this really nice. And of course I use the
deriving extensively:
newtype SubmissionId = SubmissionId { unSubmissionId :: Int }
deriving (Show,Num,Eq,Ord,Enum,Integral,Real,ShowConstant,JSON)
I have a types file with 46 newtypes, zero type aliases, and ah, 47
data types. GHCi gets kind of slow when dealing with it. My solution
is to have an Emacs shortcut to build the project with cabal every so
often so that GHCi can load the .o files in an instant.
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Re: [Haskell-cafe] Re: libefence useful for debugging ghc+ffi programs?
Excerpts from Johannes Waldmann's message of Wed Oct 20 05:13:36 -0400 2010: and indeed, gethostbyname is famous for being non re-entrant. If you have the time, this would be a great time to improve the multithreaded support of these libraries. In particular, glibc offers a re-entrant version gethostbyname_r, so at least for some POSIX systems network could be switched to using that. If all else fails, perhaps manually synchronize over an MVar and hope no one else imports the FFI. If you don't have the time, if you can identify where gethostbyname is getting called from, hopefully you can manually synchronize those sections of the program. Edward ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :)
Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Return value of a (windows) process
I have never used the above function you refer to so I am not sure about it's semantics. However, I have successfully used functions in System.Process module [1] (fairly standard) to spawn processes and get their exit codes on Windows. For example, (javac exits code 2 when provided no arguments) C:\Documents and Settings\Timjavac Usage: javac options source files where possible options include: -g Generate all debugging info ... snip C:\Documents and Settings\Timecho %ERRORLEVEL% 2 C:\Documents and Settings\Timghci GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude :m System.Process Prelude System.Process readProcessWithExitCode c:\\jdk6\\bin\ \javac.exe [] (ExitFailure 2,,Usage: javac options so... Hope this helps. - Tim [1] System.Process http://haskell.org/ghc/docs/6.12.2/html/libraries/process-1.0.1.2/System-Process.html On Oct 19, 10:12 pm, Arnaud Bailly arnaud.oq...@gmail.com wrote: Hello, I have the following code (fragment) I use to wrap execution of various processes in Haskell, in the spirit of Don Stewart's slides about Scripting in Haskell. instance MonadExec IO where exec proc args = do (exit, out, err) - liftIO $ readProcessWithExitCode proc args case exit of ExitFailure e - throwError $ userError (Fail execution of ++ program proc args ++ : ++ (show e) ++, ++err) ExitSuccess - return out Here is the abridged declaration of MonadExec: class (Monad m) = MonadExec m where exec :: String - [String] - m String The issue I am facing is that readProcessWithExitCode does not seem to return the expected failures. When I run some failing process within windows command shell, I have: D:\projets\psug-dojo\lagsd:/Program Files/scala-2.8.0/bin/scalac.bat -d target\test-classes -classpath target\classes;D:\projets\ psug-dojo\lags\test-lib\specs_2.8.0-1.6.5.jar;D:\projets\psug-dojo\lags\test-lib\scalacheck_2.8.0-1.7.jar;D:\projets\psug-dojo\lags\ test-lib\junit-4.7.jar -d target\test-classes src\test\scala\oqube\lags\LagsTest.scala src\test\scala\oqube\lags\LagsTest.scala:86: error: not found: value beS_== bid.sublists(List(Request(1,2,3))) must beS_==(List(Nil,List(Request(1,2,3 ^ one error found D:\projets\psug-dojo\lagsecho %ERRORLEVEL% 1 D:\projets\psug-dojo\lags but wrapping this same process in my shell, I always got an ExitSuccess. What am I doing wrong ? Thanks Arnaud ___ Haskell-Cafe mailing list haskell-c...@haskell.orghttp://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] Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :)
Claus Reinke posted this a while ago - see the attachment at the bottom of the message: http://www.haskell.org/pipermail/haskell-cafe/2007-July/029275.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
On Oct 20, 2010, at 11:58 AM, Gregory Crosswhite gcr...@phys.washington.edu wrote: On 10/20/10 4:09 AM, Simon Peyton-Jones wrote: No, this isn't optimised. The trouble is that you write (map Foo xs), but GHC doesn't know about 'map'. We could add a special case for map, but then you'd soon want (mapTree Foo my_tree). How about a special case for fmap? That seems like it should handle a lot of cases. Or even better, a special handling of 'id' in rules pragmas that would cause any rule matching id to also match any newtype constructor or projection. Or have the compiler automatically add rules that map all newtype wrappers and unwrappers to unsafeCoerce and make sure that unsafeCoerce has rules for map, fmap, (.), etc. --James___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: libefence useful for debugging ghc+ffi programs?
and indeed, gethostbyname is famous for being non re-entrant.
it already has a lock in Network.BSD, so I assume it's fine:
{-# NOINLINE lock #-}
lock :: MVar ()
lock = unsafePerformIO $ newMVar ()
withLock :: IO a - IO a
withLock act = withMVar lock (\_ - act)
getHostByName :: HostName - IO HostEntry
getHostByName name = withLock $ do
withCString name $ \ name_cstr - do
ent - throwNoSuchThingIfNull getHostByName no such host entry
$ trySysCall $ c_gethostbyname name_cstr
peek ent
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Re: [Haskell-cafe] Re: Return value of a (windows) process
Well, I must be doing something wrong but don't know where, the code is rather straightforward. Or the scalac.bat script is buggy: Prelude Environment System.Process readProcessWithExitCode d:/Program Files/scala-2.8.0/bin/scalac.bat [-d,target] (ExitSuccess,,Exception in thread \main\ scala.tools.nsc.FatalError: target does not exist or is not a directory\n\tat scala.tools.nsc.settings.MutableSettings$OutputDirs.checkDir(MutableSettings.scala:227)\n\tat scala.tools.nsc.settings.MutableSettings$OutputDirs.setSingleOutput(MutableSettings.scala:236)\n\tat scala.tools.nsc.settings.MutableSettings$OutputSetting.value_$eq(MutableSettings.scala:452)\n\tat scala.tools.nsc.settings.MutableSettings$OutputSetting.value_$eq(MutableSettings.scala:445)\n\tat scala.tools.nsc.settings.MutableSettings$StringSetting.tryToSet(MutableSettings.scala:418)\n\tat scala.tools.nsc.settings.MutableSettings$$anonfun$parseNormalArg$1$1$$anonfun$apply$3.apply(MutableSettings.scala:121)\n\tat scala.tools.nsc.settings.MutableSettings$$anonfun$parseNormalArg$1$1$$anonfun$apply$3.apply(MutableSettings.scala:121)\n\tat scala.tools.nsc.settings.MutableSettings.tryToSetIfExists$1(MutableSettings.scala:98)\n\tat scala.tools.nsc.settings.MutableSettings.parseNormalArg$1(MutableSettings.scala:121)\n\tat scala.tools.nsc.settings.MutableSettings.doArgs$1(MutableSettings.scala:154)\n\tat scala.tools.nsc.settings.MutableSettings.parseParams(MutableSettings.scala:160)\n\tat scala.tools.nsc.settings.MutableSettings.processArguments(MutableSettings.scala:44)\n\tat scala.tools.nsc.CompilerCommand.processArguments(CompilerCommand.scala:87)\n\tat scala.tools.nsc.CompilerCommand.init(CompilerCommand.scala:91)\n\tat scala.tools.nsc.Main$.process(Main.scala:52)\n\tat scala.tools.nsc.Main$.main(Main.scala:122)\n\tat scala.tools.nsc.Main.main(Main.scala)\n) Arnaud On Wed, Oct 20, 2010 at 8:46 PM, Tim trba...@gmail.com wrote: I have never used the above function you refer to so I am not sure about it's semantics. However, I have successfully used functions in System.Process module [1] (fairly standard) to spawn processes and get their exit codes on Windows. For example, (javac exits code 2 when provided no arguments) C:\Documents and Settings\Timjavac Usage: javac options source files where possible options include: -g Generate all debugging info ... snip C:\Documents and Settings\Timecho %ERRORLEVEL% 2 C:\Documents and Settings\Timghci GHCi, version 6.12.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude :m System.Process Prelude System.Process readProcessWithExitCode c:\\jdk6\\bin\ \javac.exe [] (ExitFailure 2,,Usage: javac options so... Hope this helps. - Tim [1] System.Process http://haskell.org/ghc/docs/6.12.2/html/libraries/process-1.0.1.2/System-Process.html On Oct 19, 10:12 pm, Arnaud Bailly arnaud.oq...@gmail.com wrote: Hello, I have the following code (fragment) I use to wrap execution of various processes in Haskell, in the spirit of Don Stewart's slides about Scripting in Haskell. instance MonadExec IO where exec proc args = do (exit, out, err) - liftIO $ readProcessWithExitCode proc args case exit of ExitFailure e - throwError $ userError (Fail execution of ++ program proc args ++ : ++ (show e) ++, ++err) ExitSuccess - return out Here is the abridged declaration of MonadExec: class (Monad m) = MonadExec m where exec :: String - [String] - m String The issue I am facing is that readProcessWithExitCode does not seem to return the expected failures. When I run some failing process within windows command shell, I have: D:\projets\psug-dojo\lagsd:/Program Files/scala-2.8.0/bin/scalac.bat -d target\test-classes -classpath target\classes;D:\projets\ psug-dojo\lags\test-lib\specs_2.8.0-1.6.5.jar;D:\projets\psug-dojo\lags\test-lib\scalacheck_2.8.0-1.7.jar;D:\projets\psug-dojo\lags\ test-lib\junit-4.7.jar -d target\test-classes src\test\scala\oqube\lags\LagsTest.scala src\test\scala\oqube\lags\LagsTest.scala:86: error: not found: value beS_== bid.sublists(List(Request(1,2,3))) must beS_==(List(Nil,List(Request(1,2,3 ^ one error found D:\projets\psug-dojo\lagsecho %ERRORLEVEL% 1 D:\projets\psug-dojo\lags but wrapping this same process in my shell, I always got an ExitSuccess. What am I doing wrong ? Thanks Arnaud ___ Haskell-Cafe mailing list haskell-c...@haskell.orghttp://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] Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :)
On Wed, Oct 20, 2010 at 3:11 PM, Stephen Tetley stephen.tet...@gmail.com wrote: Claus Reinke posted this a while ago - see the attachment at the bottom of the message: http://www.haskell.org/pipermail/haskell-cafe/2007-July/029275.html Thanks for that. Here's the relevant website that he posted later in that thread: http://www.cs.kent.ac.uk/people/staff/cr3/toolbox/haskell/browsing/ Of course, it would be nice to be able to write the javascript parts in Haskell, and even use a Haskell framework for generating the HTML. I'm sure this is possible with things like Yesod, etc. Just wanted to mention, currently I am working on a project (not in Haskell) that takes a similar approach of starting up an HTTP server and using the browser for the GUI. We are thinking about including a copy of Chromium in the binary release, and launching it on double-click with the --app flag which opens a chromeless browser window (i.e just a window border containing an HTML renderer) looking just like a local application. Another option is XULRunner, which you can use to create an application with native menus and widgets around the border, and add a browser element to the GUI which points at your Haskell web server. You could probably even generate the XUL layout code in the Haskell server if you wanted, which would provide a totally native-looking app. (At least for those who don't consider Firefox very awful-looking, I know there are some Cocoa pedants around who would complain.. ;) Steve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :)
On Wed, Oct 20, 2010 at 4:27 PM, Stephen Sinclair radars...@gmail.com wrote: On Wed, Oct 20, 2010 at 3:11 PM, Stephen Tetley stephen.tet...@gmail.com wrote: Claus Reinke posted this a while ago - see the attachment at the bottom of the message: http://www.haskell.org/pipermail/haskell-cafe/2007-July/029275.html Thanks for that. Here's the relevant website that he posted later in that thread: http://www.cs.kent.ac.uk/people/staff/cr3/toolbox/haskell/browsing/ Of course, it would be nice to be able to write the javascript parts in Haskell, and even use a Haskell framework for generating the HTML. I'm sure this is possible with things like Yesod, etc. Just wanted to mention, currently I am working on a project (not in Haskell) that takes a similar approach of starting up an HTTP server and using the browser for the GUI. We are thinking about including a copy of Chromium in the binary release, and launching it on double-click with the --app flag which opens a chromeless browser window (i.e just a window border containing an HTML renderer) looking just like a local application. Another option is XULRunner, which you can use to create an application with native menus and widgets around the border, and add a browser element to the GUI which points at your Haskell web server. You could probably even generate the XUL layout code in the Haskell server if you wanted, which would provide a totally native-looking app. (At least for those who don't consider Firefox very awful-looking, I know there are some Cocoa pedants around who would complain.. ;) P.s., it would be wrong not to also mention the latest development in UHC, which might exactly let you write the JavaScript part of the app in Haskell: http://utrechthaskellcompiler.wordpress.com/2010/10/18/haskell-to-javascript-backend/ I haven't tried it, so can't comment on the readiness of this interpreter.. Steve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: libefence useful for debugging ghc+ffi programs?
Hmm, in that case, one possibility is someone else did an FFI import of
gethostbyname and isn't using the same lock. Can you check for that?
Edward
Excerpts from Johannes Waldmann's message of Wed Oct 20 16:17:06 -0400 2010:
and indeed, gethostbyname is famous for being non re-entrant.
it already has a lock in Network.BSD, so I assume it's fine:
{-# NOINLINE lock #-}
lock :: MVar ()
lock = unsafePerformIO $ newMVar ()
withLock :: IO a - IO a
withLock act = withMVar lock (\_ - act)
getHostByName :: HostName - IO HostEntry
getHostByName name = withLock $ do
withCString name $ \ name_cstr - do
ent - throwNoSuchThingIfNull getHostByName no such host entry
$ trySysCall $ c_gethostbyname name_cstr
peek ent
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Re: [Haskell-cafe] Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :)
cas...@istar.ca wrote: Is it possible to easily connect Haskell to JavaScript/JavaFX in the browser and use a browser as a Windows GUI? :) ... I meant call Haskell functions from a browser; so the browser handles the GUI widgets and Haskell handles the processing. :) It's pretty easy to get the basics going. There are a bunch of options. Start here: http://www.haskell.org/haskellwiki/Web For what you're asking about, I'd suggest looking at the following options from that page. All of these options involve linking a web server library into your Haskell app, so it's self-contained and all you need is a browser to talk to it: #6: Snap + custom code: Snap is simple to get started with, and is good if you know exactly what HTML/Javascript you need to generate and don't mind doing it more or less manually. If you're looking for richer library support for developing HTML UIs, consider the next option. #2: Snap + Yesod: Yesod will give you many of the framework features you might want for developing web UIs. (Not sure about JavaFX though.) #1: Happstack: an ambitious web server / framework with some fancy features like its own data persistence system. One other tool worth considering if you're doing a lot of Javascript with Haskell is JMacro: http://www.haskell.org/haskellwiki/Jmacro It lets you embed Javascript code directly in Haskell, and easily embed Haskell data into that code. Anton ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
Do we really want to treat every newtype wrappers as a form of 'id'? For example: newtype Nat = Nat Integer -- must always be positive A possible rule (doesn't actually typecheck, but you get the idea): forall (x :: Nat). sqrt (x * x) = x If we ignore newtyping we get an incorrect rewrite rule. It depends on the exact implementation of which 'id's would be recognised. On 20 October 2010 21:08, James Andrew Cook mo...@deepbondi.net wrote: On Oct 20, 2010, at 11:58 AM, Gregory Crosswhite gcr...@phys.washington.edu wrote: On 10/20/10 4:09 AM, Simon Peyton-Jones wrote: No, this isn't optimised. The trouble is that you write (map Foo xs), but GHC doesn't know about 'map'. We could add a special case for map, but then you'd soon want (mapTree Foo my_tree). How about a special case for fmap? That seems like it should handle a lot of cases. Or even better, a special handling of 'id' in rules pragmas that would cause any rule matching id to also match any newtype constructor or projection. Or have the compiler automatically add rules that map all newtype wrappers and unwrappers to unsafeCoerce and make sure that unsafeCoerce has rules for map, fmap, (.), etc. --James___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Push the envelope. Watch it bend. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] JavaScript in a browser as a Windows GUI?
On 20/10/2010 09:48 PM, Anton van Straaten wrote: It's pretty easy to get the basics going. There are a bunch of options. Start here: http://www.haskell.org/haskellwiki/Web For what you're asking about, I'd suggest looking at the following options from that page. All of these options involve linking a web server library into your Haskell app, so it's self-contained and all you need is a browser to talk to it: #6: Snap + custom code: Snap is simple to get started with, and is good if you know exactly what HTML/Javascript you need to generate and don't mind doing it more or less manually. If you're looking for richer library support for developing HTML UIs, consider the next option. #2: Snap + Yesod: Yesod will give you many of the framework features you might want for developing web UIs. (Not sure about JavaFX though.) #1: Happstack: an ambitious web server / framework with some fancy features like its own data persistence system. One other tool worth considering if you're doing a lot of Javascript with Haskell is JMacro: http://www.haskell.org/haskellwiki/Jmacro It lets you embed Javascript code directly in Haskell, and easily embed Haskell data into that code. I'd like to have a go at writing CGI in Haskell. However, I don't really want to install and configure the likes of Apache just to quickly test a simple CGI script. I was hoping that I could find a trivial little HTTP server on Hackage somewhere that would be just a simple binary that I can execute and feed CGI binaries to. But alas, the closest thing I can find is http://hackage.haskell.org/package/hws Alas, this does not work on Windows since it depends on the unix package. (In fact, almost every network-related package on Hackage depends on unix, for reasons beyond my powers of comprehension...) (I also looked at non-Haskell lightweight web servers, but they all unanimously don't support CGI at all, or only support CGI _scripts_, but arbitrary executables...) Does anybody know of a solution that works on Windows? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] hs-plugins and memory leaks
I was happy to see the recent announcement about hs-plugins being updated to work with newer ghc. I have a project and had always been planning to use it. However, there are some questions I've had about it for a long time. The 'yi' paper mentions both 'yi' and 'lambdabot' as users of hs-plugins. However, both those projects have long since abandoned it. I can't find any documentation on why, or even any documentation at all for Yi wrt its dynamic code execution system, but from looking at the source it looks like it uses hint for dynamic code execution and dyre for configuration. Dyre in turn uses serialization to pass the old state to the reconfigured app. So we have retreated from the idea of hotswapping the application state. It seems to me that the advantages as put forth in the 'yi' paper still hold. Changing the configuration in yi is rather heavyweight. Relinking the entire editor takes a long time, and yi is still a relatively small program. Editors can keep most of their state on disk and can have very simple GUI state, so perhaps the serialization and deserialization isn't such a problem, but this doesn't hold for other programs. It seems to me the loss is significant: there's a big difference between being able to experiment with a command by editing and rerunning it immediately, and having to wait 10s or more for the app to recompile, relink, shut down the ui, serialize all state, and restart. And if you add hint, you are linking in large parts of ghc, with an even slower link time. So, yi is no longer a dynamically reconfigurable application, and is now merely a configurable application. The apparent loss of such a useful feature (you might even say a defining feature) would presumably only happen if keeping it was untenable. And of course that makes me reluctant to make any kind of design that relies on it without first knowing why all existing users jumped ship. I can think of one possible reason, and that's a memory leak. In ghc/rts/Linker.c:unloadObj there's a commented out line '// stgFree(oc-image);'. In a test program I wrote that behaves like 'plugs', every executed line increases the size of the program by 12-16k. I have to remove the resolveObjs call from plugs for it to work, but once I do it displays the same leak. So my questions are: Why did lambdabot and yi abandon plugins? Is unloadObj a guaranteed memory leak? As far as I can tell, it's never called within ghc itself. If the choices are between a memory leak no matter how you use it and dangerous but correct if you use it right, shouldn't we at least have the latter available as an option? E.g. a reallyUnloadObj function that also frees the image. If I uncomment that line will it fix the problem? Is it safe to do so if I first force all thunks that might contain unloaded code? Long shot, but are there any more principled ways to guarantee no pointers to a chunk of code exist? The only thing I can think of is to have the state be totally strict and consist only of types from the static core. Would it be possible to hand responsibility for the memory off to the garbage collector? GHC now supports dynamic libraries. Given that plugins may need to link large portions of the static core library, can it be loaded as a dynamic library so both the core and the plugins can share the same code? I haven't been able to find many references to ghc's support for dynamic linking. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] hs-plugins and memory leaks
qdunkan: However, there are some questions I've had about it for a long time. The 'yi' paper mentions both 'yi' and 'lambdabot' as users of hs-plugins. However, both those projects have long since abandoned it. I can't find any documentation on why, or even any documentation at all for Yi wrt its dynamic code execution system, but from looking at the source it looks like it uses hint for dynamic code execution and dyre for configuration. Dyre in turn uses serialization to pass the old state to the reconfigured app. So we have retreated from the idea of hotswapping the application state. Once active development of hs-plugins stopped, along with the portability issues, it behooved projects like e.g. xmonad or yi, to aim for simpler reconfiguration strategies, other than native code hot loading. I can think of one possible reason, and that's a memory leak. In ghc/rts/Linker.c:unloadObj there's a commented out line '// stgFree(oc-image);'. In a test program I wrote that behaves like 'plugs', every executed line increases the size of the program by 12-16k. I have to remove the resolveObjs call from plugs for it to work, but once I do it displays the same leak. So my questions are: Why did lambdabot and yi abandon plugins? Because it was unmaintained for around 5 years, and was fundamentally less portable than simpler state serialization solutions that offered some of the same benefits as full code hot swapping. Is unloadObj a guaranteed memory leak? As far as I can tell, it's never called within ghc itself. If the choices are between a memory leak no matter how you use it and dangerous but correct if you use it right, shouldn't we at least have the latter available as an option? E.g. a reallyUnloadObj function that also frees the image. GHC never unloads object code, so yes, it will leak old code. Long shot, but are there any more principled ways to guarantee no pointers to a chunk of code exist? The only thing I can think of is to have the state be totally strict and consist only of types from the static core. Would it be possible to hand responsibility for the memory off to the garbage collector? It's really hard. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] JavaScript in a browser as a Windows GUI?
You can use Network.Wai.Handler.SimpleServer from wai-extra[1]. If you want a full framework, Yesod[2] has full Windows support. Michael [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/wai-extra [2] http://docs.yesodweb.com/ On Wed, Oct 20, 2010 at 11:10 PM, Andrew Coppin andrewcop...@btinternet.com wrote: On 20/10/2010 09:48 PM, Anton van Straaten wrote: It's pretty easy to get the basics going. There are a bunch of options. Start here: http://www.haskell.org/haskellwiki/Web For what you're asking about, I'd suggest looking at the following options from that page. All of these options involve linking a web server library into your Haskell app, so it's self-contained and all you need is a browser to talk to it: #6: Snap + custom code: Snap is simple to get started with, and is good if you know exactly what HTML/Javascript you need to generate and don't mind doing it more or less manually. If you're looking for richer library support for developing HTML UIs, consider the next option. #2: Snap + Yesod: Yesod will give you many of the framework features you might want for developing web UIs. (Not sure about JavaFX though.) #1: Happstack: an ambitious web server / framework with some fancy features like its own data persistence system. One other tool worth considering if you're doing a lot of Javascript with Haskell is JMacro: http://www.haskell.org/haskellwiki/Jmacro It lets you embed Javascript code directly in Haskell, and easily embed Haskell data into that code. I'd like to have a go at writing CGI in Haskell. However, I don't really want to install and configure the likes of Apache just to quickly test a simple CGI script. I was hoping that I could find a trivial little HTTP server on Hackage somewhere that would be just a simple binary that I can execute and feed CGI binaries to. But alas, the closest thing I can find is http://hackage.haskell.org/package/hws Alas, this does not work on Windows since it depends on the unix package. (In fact, almost every network-related package on Hackage depends on unix, for reasons beyond my powers of comprehension...) (I also looked at non-Haskell lightweight web servers, but they all unanimously don't support CGI at all, or only support CGI _scripts_, but arbitrary executables...) Does anybody know of a solution that works on Windows? ___ 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] Haskell Weekly News: Issue 155 - October 20, 2010
Welcome to issue 155 of the HWN, a newsletter covering developments in the [1]Haskell community in the week of October 10 - 16. This time around we again have 87 posts to HackageDB. Instead of posting the individual packages, we get to see and celebrate the 43 people behind these efforts. Want to keep a close eye on the haskellers that lurk twitter? Don Steward made [2]a twitter list of tweeting haskellers! Let him know if you'd like to be added to the list. There were a total of 24 new stories posted to the Haskell Reddit channel, 27 new questions taged with Haskell in StackOverflow, and 408 messages posted to Haskell-Cafe. So, what was hot last week? Announcements Gregory Crosswhite is pleased to [3]announce the release of a family of packages for type-level natural numbers. He also [4]announced tagged-list, a package which provides fixed-length lists that are tagged with a phantom type-level natural number corresponding to the length. Janis Voigtlander [5]announced that it is time to collect contributions for the 19th edition of the Haskell Communities Activities Report. The submission deadline is November 1, 2010. Alexander Solla [6]announced his new Facts library. The Facts hierarchy is meant to contain commonly used, relatively static facts about the real world. Kevin Jardine [7]announced polyToMonoid: a library that supplies two very general polyvariadic functions that can map their arguments into any monoid you specify. Simon Hengel [8]announced a new version of DocTest. DocTest now uses Haddock for parsing of comments. Interesting Threads on Haskell-Cafe Michael Snoyman [9]reported that Haskellers.com has become popular a lot falter that he anticipated. Read up on what changes are planned for Haskellers.com. Michael is very interested in some help with running the site. Jacek Generowicz [10]asked how to deal with dynamic dispatch on extensible sets of types. Uwe Schmidt [11]replied to a question about why HXT uses arrows as opposed to using monads. Good comments followed. Jason Dusek [12]asked if there is a way to write a Haskell data structure that is necessarily only one or two or seventeen items long; but that is nonetheless statically guaranteed to be of finite length? Twenty-three messages followed. Simon Thompson [13]annouced the availability of books for review for the Journal of Functonial Programming. Andrew Copping [14]summarized a report produced by Google Szwitzerland on taking a Python system and rewriting bits of it in Haskell, some of which is now in production use. Ben Franksen [15]ranted about the current Haskell Blurb on the first paragraph of haskell.org. Quite the read to end the week :) Top Reddit Stories * Using Haskell’s ‘newtype’ in C Domain: blog.nelhage.com Score: 37, Comments: 5 On Reddit: http://www.reddit.com/r/haskell/comments/dptzh/using_haskells_newtype_in_c/ Original: http://blog.nelhage.com/2010/10/using-haskells-newtype-in-c/ * The Haskell theme: consistent visual branding for Haskell Domain: haskell.org Score: 34, Comments: 11 On Reddit: http://www.reddit.com/r/haskell/comments/dqiej/the_haskell_theme_consistent_visual_branding_for/ Original: http://www.haskell.org/pipermail/haskell-cafe/2010-October/084781.html * Haskellers: Survey results and new site features Domain: haskellers.com Score: 22, Comments: 6 On Reddit: http://www.reddit.com/r/haskell/comments/dr37b/haskellers_survey_results_and_new_site_features/ Original: http://www.haskellers.com/news/1/ * My Experience Learning Haskell Domain: blog.virtucal.com Score: 21, Comments: 6 On Reddit: http://www.reddit.com/r/haskell/comments/drgcz/my_experience_learning_haskell/ Original: http://blog.virtucal.com/cyclical/2010/10/14/my-experience-learning-haskell.html * Invertible monads for exception handling and memory allocations Domain: docs.yesodweb.com Score: 21, Comments: 0 On Reddit: http://www.reddit.com/r/haskell/comments/drkdj/invertible_monads_for_exception_handling_and/ Original: http://docs.yesodweb.com/blog/invertible-monads-exceptions-allocations/ * Accelerating Haskell Array Codes with Multicore GPUs Domain: justtesting.org Score: 19, Comments: 0 On Reddit: http://www.reddit.com/r/haskell/comments/dq1yo/accelerating_haskell_array_codes_with_multicore/ Original: http://justtesting.org/accelerating-haskell-array-codes-with-multico * Unicode text performance improvements Domain: serpentine.com Score: 17, Comments: 1 On Reddit: http://www.reddit.com/r/haskell/comments/drinz/unicode_text_performance_improvements/ Original: http://www.serpentine.com/blog/2010/10/15/unicode-text-performance-improvements/ * Like a coding challenge? Check out Code Quarterly! Domain: serpentine.com Score: 16,
Re: [Haskell-cafe] hs-plugins and memory leaks
So my questions are:
Why did lambdabot and yi abandon plugins?
Because it was unmaintained for around 5 years, and was fundamentally
less portable than simpler state serialization solutions that offered
some of the same benefits as full code hot swapping.
Fair enough. The idea of being able to make changes and see them
quickly enough for it to have an interactive feel is very appealing,
but maybe there are other ways to get there, such as improving link
time with dynamic linking (my current link time is around 24 seconds).
State serialization + restart is definitely simpler and more robust.
But if it's impossible to get it fast enough otherwise, and there
aren't any other show stopping problems (I think even a known memory
leak may be dwarfed by the amount of data the app keeps in memory
anyway), then it might be worth it to me to maintain hs-plugins.
Is unloadObj a guaranteed memory leak? As far as I can tell, it's
never called within ghc itself. If the choices are between a memory
leak no matter how you use it and dangerous but correct if you use it
right, shouldn't we at least have the latter available as an option?
E.g. a reallyUnloadObj function that also frees the image.
GHC never unloads object code, so yes, it will leak old code.
So would freeing oc-image fix the leak? In my case, it's not too
hard to force all data structures that might reference it.
Long shot, but are there any more principled ways to guarantee no
pointers to a chunk of code exist? The only thing I can think of is
to have the state be totally strict and consist only of types from the
static core. Would it be possible to hand responsibility for the
memory off to the garbage collector?
It's really hard.
It happens in python for python bytecode, since it exists as a plain
data structure in the language. E.g. 'code = compile('xyz')'.
Couldn't a haskell solution be along the same lines? 'code - load
X.o; makeFunction code', and then makeFunction holds a ForeignPtr to
the actual code and there's some kind of primitive to call a chunk of
code as a function.
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[Haskell-cafe] Re: libefence useful for debugging ghc+ffi programs?
OK, never mind, I found the problem in my C code. some uninitialized variables - mostly they were 0, but sometimes not: I guess when I got mallocForeignPtrBytes that were just freed by the garbage collector. Although the program does a ton of allocations, most start with memcpy of something that the program computed earlier, expect for a handfull of root nodes. But these were allocated early, when there was little garbage, so I got most of them in their zeroed-out initial state, and that's why the error did not show. (At least that's my guess.) This restores my faith in ghc, ffi, and library writers - and shows how much I unlearned C programming (which I guess is generally a good thing - except when you program C). J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] [ANNAUNCE] ghcjs-0.1.0 Haskell to Javascript compiler
I've been working on this for some month and I think now I'm ready to share the results. http://github.com/sviperll/ghcjs Haskell to Javascript translator Project aims to provide solution to * compile modern Haskell libraries to Javascript files and use them in Ajax applications or * develop entire Ajax application in Haskell language Building Code builds as standard haskell package $ runghc Setup configure $ runghc Setup build $ runghc Setup install Usage - To compile Haskell module to Javascript use `ghcjs` command. $ ghcjs Test.hs This command is merely equivalent to the following $ ghc --make Test.hs but it compiles to Javascript instead of native code. See examples folder for an example of loading and running haskell code from browser. Status -- The code is in alpha stage. Feel free to experiment with it as you wish. Implementation -- Compiler is implemented as [GHC](http://www.haskell.org/ghc/) backend using GHC API. And been tested with GHC 6.12.1. -- Victor Nazarov ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
On 10/20/10 7:09 AM, Simon Peyton-Jones wrote: Yes, you can freely use Foo/unFoo. There's no runtime penalty. (In the jargon of GHC's intermediate language, Foo and unFoo translate to *type-safe casts*, which generate no executable code. When does the conversion to type-safe casts occur relative to other optimizations (namely, rewrite rules)? -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] playing around with network.curl
I'm using this tutorial as a guide http://flygdynamikern.blogspot.com/2009/03/extended-sessions-with-haskell-curl.html github has changed since this was posted, but I have managed a successful login. Now I am faced with dealing with a re-direct. I found this constructor CurlFollowLocation Bool on this page http://hackage.haskell.org/packages/archive/curl/1.3.5/doc/html/Network-Curl-Opts.html It seems to do what I want, But I am not clear on how to use it. Could someone provide an example? Thanks. End goal is to snarf the cookie that establishes the session. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
On Thursday 21 October 2010 01:11:25, wren ng thornton wrote: On 10/20/10 7:07 PM, wren ng thornton wrote: On 10/20/10 7:09 AM, Simon Peyton-Jones wrote: Yes, you can freely use Foo/unFoo. There's no runtime penalty. (In the jargon of GHC's intermediate language, Foo and unFoo translate to *type-safe casts*, which generate no executable code. When does the conversion to type-safe casts occur relative to other optimizations (namely, rewrite rules)? That is, I know that rewrite rules operate on the source language not on Core, but to what extent does that mean that type-safe casts inhibit the firing of rules? Pretty much completely, I'm afraid. There's a rewrite rule for realToFrac :: Double - Float. Build yourself a benchmark for that transformation that runs some measurable time (say 0.1 seconds or so). Now use a newtype wrapper around Float instead (and don't add a rewrite rule for it). Ouch. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] playing around with network.curl
Hi Michael, On Wed, Oct 20, 2010 at 6:19 PM, Michael Litchard mich...@schmong.org wrote: I'm using this tutorial as a guide http://flygdynamikern.blogspot.com/2009/03/extended-sessions-with-haskell-curl.html github has changed since this was posted, but I have managed a successful login. Now I am faced with dealing with a re-direct. I found this constructor CurlFollowLocation Bool on this page http://hackage.haskell.org/packages/archive/curl/1.3.5/doc/html/Network-Curl-Opts.html It seems to do what I want, But I am not clear on how to use it. Could someone provide an example? Thanks. End goal is to snarf the cookie that establishes the session. I think it is what you're probably expecting. Just add CurlFollowLocation True to the list of options. Those get applied by setopts in main. opts = [ CurlCookieJar cookies, CurlFollowLocation True ] I've used that before with no problems. Do you need a complete example? Paulo ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] JavaScript in a browser as a Windows GUI?
Andrew Coppin wrote: I'd like to have a go at writing CGI in Haskell. ... Does anybody know of a solution that works on Windows? I've previously run Happstack on Windows. That was a couple of years ago, though, so I don't know whether its Windows support is currently working. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: How to make cabal pass flags to happy?
On Wed, 2010-10-20 at 10:37 +0200, Niklas Broberg wrote: I think the right solution is for the happy source file to specify what kind of grammar it is / should be produced. Yes, that would mean modifying happy. Hmm, I agree with you in this particular case, regarding the grammar, since it really only makes sense for any given happy grammar to generate either kind of parser. But such a solution still wouldn't answer the general question about passing flags to preprocessors. Certainly not all such use cases are best fixed by pushing the flags into the pre-processed files. I like to see it as an issue of the design of the whole system, not just adapting cabal to existing half-thought-out tools. With preprocessor flags the first question is who picks the flags. If it is the person doing the build then we handle that already. If it is the package author then it needs more careful analysis. Yes we could go and add a foo-options for every single pre-processor but that's not obviously a good idea. Yes you can have full control by writing code in the Setup.hs (and it could be easier to do that) but again it's not a very nice solution in general. I think we have a habit of just adding flags to such tools and saying let the build system handle it without really thinking carefully about where the right place to specify things should be. My view is that for the most part, source modules ought to be self-descriptive so that they can be built with zero configuration. For basic Haskell modules we do this already, we have a standard convention on file extension, file - module name mapping, language pragmas, etc etc. This is what allows ghci / ghc --make to work in most cases (and in principle should allow a future cabal to work even without a .cabal file for many simple projects -- like hmake did for years). For preprocessors we have some convention, we mostly use file name extensions. For more detailed variations I think it does make sense to stick it in the source module. The harder cases are things like preprocessors which genuinely have multiple modes. I don't mean things like happy's GLR since as I understand it you really design the grammar specifically for the approach. There are other tools where from the same source you can and do generate multiple outputs. There it is harder to establish a convention that allows for zero-configuration. Similarly, documentation is a mess because there are few established conventions, so much more grungy configuration is needed. Duncan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: hs-plugins and memory leaks
Hi Evan,
Evan Laforge qdun...@gmail.com writes:
So my questions are:
Why did lambdabot and yi abandon plugins?
Because it was unmaintained for around 5 years, and was fundamentally
less portable than simpler state serialization solutions that offered
some of the same benefits as full code hot swapping.
Fair enough. The idea of being able to make changes and see them
quickly enough for it to have an interactive feel is very appealing,
but maybe there are other ways to get there, such as improving link
time with dynamic linking (my current link time is around 24 seconds).
State serialization + restart is definitely simpler and more robust.
But if it's impossible to get it fast enough otherwise, and there
aren't any other show stopping problems (I think even a known memory
leak may be dwarfed by the amount of data the app keeps in memory
anyway), then it might be worth it to me to maintain hs-plugins.
I have project design for use dynamic linking, i even build 'pdynload'
(http://hackage.haskell.org/package/pdynload-0.0.3) with Don's PhD
thesis.
Last, i remove pdynload code from my project temporary with below reasons:
1) Hold running state is difficult, like network state in browser or
running state in terminal emulator.
2) Linking time is too long, I have haskell OS project
(http://www.flickr.com/photos/48809...@n02/) have many sub-module, every
sub-module is very big, and linking time is too long.
3) Memory leak like you said.
Is unloadObj a guaranteed memory leak? As far as I can tell, it's
never called within ghc itself. If the choices are between a memory
leak no matter how you use it and dangerous but correct if you use it
right, shouldn't we at least have the latter available as an option?
E.g. a reallyUnloadObj function that also frees the image.
GHC never unloads object code, so yes, it will leak old code.
So would freeing oc-image fix the leak? In my case, it's not too
hard to force all data structures that might reference it.
It's not safe for GHC runtime system since you don't know when time
unload old code is safe.
Don's idea is hold old state in memory even you load new state for
hot-swapping safely.
Long shot, but are there any more principled ways to guarantee no
pointers to a chunk of code exist? The only thing I can think of is
to have the state be totally strict and consist only of types from the
static core. Would it be possible to hand responsibility for the
memory off to the garbage collector?
It's really hard.
It happens in python for python bytecode, since it exists as a plain
data structure in the language. E.g. 'code = compile('xyz')'.
Couldn't a haskell solution be along the same lines? 'code - load
X.o; makeFunction code', and then makeFunction holds a ForeignPtr to
the actual code and there's some kind of primitive to call a chunk of
code as a function.
Anyway, i was re-thinking hot-swap haskell some time, my idea
is :
multi-processes framework
+ hot-swapping core entry
+ mix old/new sub-module in runtime
Core and sub-module all in separate processes.
With my project (http://www.flickr.com/photos/48809...@n02/), editor and
browser (many other sub-module ...) are sub-module.
Core don't do anything, just control how to load sub-module.
Core have 'entry code', like 'pageBufferNewFun' in
https://patch-tag.com/r/AndyStewart/manatee/snapshot/current/content/pretty/Manatee.hs
'sourceBufferNew', 'browserBufferNew' are 'entry function' to load sub-module
in *new*
process.
Core process always running, so we just need hot-swapping 'entry code' after we
update sub-module
library by cabal, then we can use new 'entry code' load sub-module in new
process, at the same
time, old sub-module code still running in old process.
Welcome to discuss. :)
Cheers,
-- Andy
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Re: [Haskell-cafe] playing around with network.curl
I'm afraid I'll need a more complete example. When I try to modify the code above (after correcting the conditional tests), I get the following: * About to connect() to github.com port 443 (#0) * Trying 207.97.227.239... * connected * Connected to github.com (207.97.227.239) port 443 (#0) * found 142 certificates in /etc/ssl/certs/ca-certificates.crt *server certificate verification SKIPPED *common name: *.github.com (matched) *server certificate expiration date OK *server certificate activation date OK *certificate public key: RSA *certificate version: #3 *subject: O=*.github.com,OU=Domain Control Validated,CN=*.github.com *start date: Fri, 11 Dec 2009 05:02:36 GMT *expire date: Thu, 11 Dec 2014 05:02:36 GMT *issuer: C=US,ST=Arizona,L=Scottsdale,O=GoDaddy.com\, Inc.,OU=http://certificates.godaddy.com/repository,CN=Go Daddy Secure Certification Authority,serialNumber=07969287 *compression: NULL *cipher: AES-128-CBC *MAC: SHA1 GET /session HTTP/1.1 Host: github.com Accept: */* HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: http://github.com/session X-Runtime: 0ms Content-Length: 91 * Added cookie _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f for domain github.com, path /, expire 1577865600 Set-Cookie: _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f; path=/; expires=Wed, 01 Jan 2020 08:00:00 GMT; HttpOnly Cache-Control: no-cache * Ignoring the response-body * Connection #0 to host github.com left intact * Issue another request to this URL: 'http://github.com/session' * About to connect() to github.com port 80 (#1) * Trying 207.97.227.239... * connected * Connected to github.com (207.97.227.239) port 80 (#1) GET /session HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: http://github.com/login X-Runtime: 1ms Content-Length: 89 * Replaced cookie _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 for domain github.com, path /, expire 1577865600 Set-Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5; path=/; expires=Wed, 01 Jan 2020 08:00:00 GMT; HttpOnly Cache-Control: no-cache * Ignoring the response-body * Connection #1 to host github.com left intact * Issue another request to this URL: 'http://github.com/login' * Re-using existing connection! (#1) with host github.com * Connected to github.com (207.97.227.239) port 80 (#1) GET /login HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: https://github.com/login X-Runtime: 0ms Content-Length: 90 Cache-Control: no-cache * Ignoring the response-body * Connection #1 to host github.com left intact * Issue another request to this URL: 'https://github.com/login' * Re-using existing connection! (#0) with host github.com * Connected to github.com (207.97.227.239) port 443 (#0) GET /login HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 HTTP/1.1 200 OK Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 200 OK ETag: 00d0a01a93453f641cecb212b6487496 X-Runtime: 10ms Content-Length: 15622 * Added cookie csrf_id=f3ff252d5245dc4da10f0c75badbd10c for domain github.com, path /, expire 0 Set-Cookie: csrf_id=f3ff252d5245dc4da10f0c75badbd10c; path=/ Cache-Control: private, max-age=0, must-revalidate * Connection #0 to host github.com left intact *** Exception: Failed to log in: CurlOK -- HTTP/1.1 302 Found *Main * Closing connection #1 * Closing connection #0 Here's what the code looks like. Notice there's a condition test for a Status of 302, but that test fails where it should have succeeded. Removing the CurlFollowLOcation
Re: [Haskell-cafe] Re: hs-plugins and memory leaks
Last, i remove pdynload code from my project temporary with below reasons: 1) Hold running state is difficult, like network state in browser or running state in terminal emulator. This doesn't seem too hard to me. Provided you are not swapping the module that defines the state in the first place, simply reload the module, and replace the old symbol in the state with the reloaded one. 2) Linking time is too long, I have haskell OS project (http://www.flickr.com/photos/48809...@n02/) have many sub-module, every sub-module is very big, and linking time is too long. This is discouraging, since one of the main reasons to use dynamically loaded code instead of recompiling the whole app is to avoid long link times. Presumably you would compile the majority of the app (the API that the plugins use, and the internal code also uses) as a dynamic library: main.o - tiny stub that just calls app.so app.so - large library containing all app logic plugin.so - links against app.so when loaded So the plugin needs to read a lot of hi files when recompiling, but the dynamic link time should be proportional to the number of unresolved symbols in plugin.so that point into app.so, not proportional to the overall size of the app, right? So would freeing oc-image fix the leak? In my case, it's not too hard to force all data structures that might reference it. It's not safe for GHC runtime system since you don't know when time unload old code is safe. But that's just my question, I *do* (think I) know when it's safe, which is after the data that has passed through plugged-in code has been fully forced. Can't I just call unloadObj then? E.g., loading and unloading plugins for audio processing is totally standard. Since the data is strict arrays of primitive types, there's no risk of stray pointers to unloaded code. Anyway, i was re-thinking hot-swap haskell some time, my idea is : multi-processes framework + hot-swapping core entry + mix old/new sub-module in runtime Core and sub-module all in separate processes. How would you pass state between processes? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [ANNAUNCE] ghcjs-0.1.0 Haskell to Javascript compiler
On 21/10/2010, at 12:01 PM, Victor Nazarov wrote: I've been working on this for some month and I think now I'm ready to share the results. Given that this is alpha code, what's the performance like? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Are newtypes optimised and how much?
On Oct 20, 2010, at 5:06 PM, Thomas Schilling nomin...@googlemail.com wrote: Do we really want to treat every newtype wrappers as a form of 'id'? For example: newtype Nat = Nat Integer -- must always be positive A possible rule (doesn't actually typecheck, but you get the idea): forall (x :: Nat). sqrt (x * x) = x If we ignore newtyping we get an incorrect rewrite rule. It depends on the exact implementation of which 'id's would be recognised. That wouldn't be generalized to id, the special treatment would only apply to rule that _mention_ Prelude.id explicitly. Such rules would implicitly fire when, say, fmap Nat xs occurs because Nat would be considered a specialization of id in the (pattern side of) rule fmap id = id. Rules mentioning Nat would not be magical in any way. -- James___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: hs-plugins and memory leaks
Evan Laforge qdun...@gmail.com writes: Last, i remove pdynload code from my project temporary with below reasons: 1) Hold running state is difficult, like network state in browser or running state in terminal emulator. This doesn't seem too hard to me. Provided you are not swapping the module that defines the state in the first place, simply reload the module, and replace the old symbol in the state with the reloaded one. 2) Linking time is too long, I have haskell OS project (http://www.flickr.com/photos/48809...@n02/) have many sub-module, every sub-module is very big, and linking time is too long. This is discouraging, since one of the main reasons to use dynamically loaded code instead of recompiling the whole app is to avoid long link times. Presumably you would compile the majority of the app (the API that the plugins use, and the internal code also uses) as a dynamic library: main.o - tiny stub that just calls app.so app.so - large library containing all app logic plugin.so - links against app.so when loaded So the plugin needs to read a lot of hi files when recompiling, but the dynamic link time should be proportional to the number of unresolved symbols in plugin.so that point into app.so, not proportional to the overall size of the app, right? Yes, not proportional the size of application, but link time depend on the dependent packages that haven't linked. Example like the GHC API in 'pdynload' package, it will search symbol define in GHC database to get which packageId that need re-link, then use below code link: Linker.linkPackages flags [packageId] Function 'linkPackages' will link specified package and it's dependent packages, if dependents packages is bigger, link time is longer. So the long link time is unavoidable for *big* package. So would freeing oc-image fix the leak? In my case, it's not too hard to force all data structures that might reference it. It's not safe for GHC runtime system since you don't know when time unload old code is safe. But that's just my question, I *do* (think I) know when it's safe, which is after the data that has passed through plugged-in code has been fully forced. Can't I just call unloadObj then? Yes, unloadObj can work if you careful design, well it's also easy to crash your program if something miss. E.g., loading and unloading plugins for audio processing is totally standard. Since the data is strict arrays of primitive types, there's no risk of stray pointers to unloaded code. Anyway, i was re-thinking hot-swap haskell some time, my idea is : multi-processes framework + hot-swapping core entry + mix old/new sub-module in runtime Core and sub-module all in separate processes. How would you pass state between processes? Infact, i won't pass any state between processes. My framework like this: http://www.flickr.com/photos/48809...@n02/5031811365/lightbox/ Every sub-module running in render process, and render process for daemon process just a *Tab*. When you need update current sub-module, just recompile new code in Cabal/GHC database, then startup *new* process to load new code, and we can use dyre technology to restore state in new process. Though it's not powerful as hs-plugins do, but perfect safety and no *memory leak*. -- Andy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] playing around with network.curl
On Wed, Oct 20, 2010 at 8:31 PM, Michael Litchard mich...@schmong.org wrote: I'm afraid I'll need a more complete example. When I try to modify the code above (after correcting the conditional tests), I get the following: * About to connect() to github.com port 443 (#0) * Trying 207.97.227.239... * connected * Connected to github.com (207.97.227.239) port 443 (#0) * found 142 certificates in /etc/ssl/certs/ca-certificates.crt * server certificate verification SKIPPED * common name: *.github.com (matched) * server certificate expiration date OK * server certificate activation date OK * certificate public key: RSA * certificate version: #3 * subject: O=*.github.com,OU=Domain Control Validated,CN=*.github.com * start date: Fri, 11 Dec 2009 05:02:36 GMT * expire date: Thu, 11 Dec 2014 05:02:36 GMT * issuer: C=US,ST=Arizona,L=Scottsdale,O=GoDaddy.com\, Inc.,OU=http://certificates.godaddy.com/repository,CN=Go Daddy Secure Certification Authority,serialNumber=07969287 * compression: NULL * cipher: AES-128-CBC * MAC: SHA1 GET /session HTTP/1.1 Host: github.com Accept: */* HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: http://github.com/session X-Runtime: 0ms Content-Length: 91 * Added cookie _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f for domain github.com, path /, expire 1577865600 Set-Cookie: _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f; path=/; expires=Wed, 01 Jan 2020 08:00:00 GMT; HttpOnly Cache-Control: no-cache * Ignoring the response-body * Connection #0 to host github.com left intact * Issue another request to this URL: 'http://github.com/session' * About to connect() to github.com port 80 (#1) * Trying 207.97.227.239... * connected * Connected to github.com (207.97.227.239) port 80 (#1) GET /session HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BiIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--884981fc5aa85daf318eeff084d98e2cff92578f HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: http://github.com/login X-Runtime: 1ms Content-Length: 89 * Replaced cookie _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 for domain github.com, path /, expire 1577865600 Set-Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5; path=/; expires=Wed, 01 Jan 2020 08:00:00 GMT; HttpOnly Cache-Control: no-cache * Ignoring the response-body * Connection #1 to host github.com left intact * Issue another request to this URL: 'http://github.com/login' * Re-using existing connection! (#1) with host github.com * Connected to github.com (207.97.227.239) port 80 (#1) GET /login HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 HTTP/1.1 302 Found Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 302 Found Location: https://github.com/login X-Runtime: 0ms Content-Length: 90 Cache-Control: no-cache * Ignoring the response-body * Connection #1 to host github.com left intact * Issue another request to this URL: 'https://github.com/login' * Re-using existing connection! (#0) with host github.com * Connected to github.com (207.97.227.239) port 443 (#0) GET /login HTTP/1.1 Host: github.com Accept: */* Cookie: _github_ses=BAh7BzoRbG9jYWxlX2d1ZXNzMCIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsABjoKQHVzZWR7AA%3D%3D--e10506e0f6935897cafe4f56774e20aa35e579a5 HTTP/1.1 200 OK Server: nginx/0.7.67 Date: Thu, 21 Oct 2010 01:20:13 GMT Content-Type: text/html; charset=utf-8 Connection: keep-alive Status: 200 OK ETag: 00d0a01a93453f641cecb212b6487496 X-Runtime: 10ms Content-Length: 15622 * Added cookie csrf_id=f3ff252d5245dc4da10f0c75badbd10c for domain github.com, path /, expire 0 Set-Cookie: csrf_id=f3ff252d5245dc4da10f0c75badbd10c; path=/ Cache-Control: private, max-age=0, must-revalidate * Connection #0 to host github.com left intact *** Exception: Failed to log in: CurlOK -- HTTP/1.1 302 Found *Main * Closing connection #1 * Closing
Re: [Haskell-cafe] JavaScript in a browser as a Windows GUI?
On Oct 20, 2010, at 7:28 PM, Anton van Straaten wrote: Andrew Coppin wrote: I'd like to have a go at writing CGI in Haskell. ... Does anybody know of a solution that works on Windows? I've previously run Happstack on Windows. That was a couple of years ago, though, so I don't know whether its Windows support is currently working. It should work. Windows is an officially supported happstack platform. All releases are tested to ensure they work under Windows. - jeremy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] data.time.zoneinfo
I am trying to figure out how to use this library, seems like this should work Prelude Data.Time.ZoneInfo ctx - newContext Nothing Prelude Data.Time.ZoneInfo name - zoneInfoName (utcOlsonZone ctx) True Prelude Data.Time.ZoneInfo newOlsonZone ctx name *** Exception: Data.Time.ZoneInfo.newOlsonZone: invalid argument (Invalid argument) but it doesn't, neither does Prelude Data.Time.ZoneInfo newOlsonZone ctx America/New_York *** Exception: Data.Time.ZoneInfo.newOlsonZone: invalid argument (Invalid argument) and my zoneinfo seems to be kosher on my machine $ ls /usr/share/zoneinfo/America/New_York /usr/share/zoneinfo/America/New_York $ ls /usr/share/zoneinfo/GMT /usr/share/zoneinfo/GMT what am i missing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: data.time.zoneinfo
passing a full path seems to work, despite the fact that the documentation says newContext :: Maybe String - IO ContextSource Create a Context object. A path to the zone-info database may be specified. Otherwise, the TZDIR environment variable, or a reasonable default, will be used. An IOError will be thrown on failure. On Wed, Oct 20, 2010 at 10:40 PM, Anatoly Yakovenko aeyakove...@gmail.com wrote: I am trying to figure out how to use this library, seems like this should work Prelude Data.Time.ZoneInfo ctx - newContext Nothing Prelude Data.Time.ZoneInfo name - zoneInfoName (utcOlsonZone ctx) True Prelude Data.Time.ZoneInfo newOlsonZone ctx name *** Exception: Data.Time.ZoneInfo.newOlsonZone: invalid argument (Invalid argument) but it doesn't, neither does Prelude Data.Time.ZoneInfo newOlsonZone ctx America/New_York *** Exception: Data.Time.ZoneInfo.newOlsonZone: invalid argument (Invalid argument) and my zoneinfo seems to be kosher on my machine $ ls /usr/share/zoneinfo/America/New_York /usr/share/zoneinfo/America/New_York $ ls /usr/share/zoneinfo/GMT /usr/share/zoneinfo/GMT what am i missing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
