Re: [Haskell-cafe] Functional programmer's intuition for adjunctions?
ajb-2 wrote: > > In Haskell, natural transformations are > functions that respect the structure of functors. Since you can't > avoid respecting the structure of functors (the language won't let you > do otherwise), you get natural transformations for free. (Free as > in theorems, not free as in beer.) > It's worth noting that polymorphism is one of those unavoidable, albeit hidden, functors. Polymorphizing a function "forall a" can be thought of as lifting it via the ((->) T_a) functor, where T_a is the type variable of "a". E.g. reverse really has the signature T_a -> [a] -> [a]. But ((->) T_a) is left adjoint to ((,) T_a), which just happens to be the analogous type-explicit way of representing existentials. Adjunctions are a useful tool to describe and analyze such dualities precisely. ajb-2 wrote: > > Adjunctions, on the other hand, you have to make yourself. As such, > they're more like monads. > Constructing adjunctions, comprising as they do of a pair of functors, does seem double the work of a single monad. Duality OTOH is a powerful guiding principle and may well be easier than working with the monad laws directly. And besides, you get a comonad for free. ajb-2 wrote: > > One thing that springs to mind is that an adjunction could connect > monads and their associated comonads. Is that a good picture? > Definitely. -- View this message in context: http://www.nabble.com/Functional-programmer%27s-intuition-for-adjunctions--tp15832225p15866753.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haddock Documentation for Yhc Web Service available online
Hi, I have regenerated Haddock documentation for Haskell modules included into the Yhc Web Service. http://www.golubovsky.org:5984/_utils/yhcws/index.html Thanks. -- Dimitry Golubovsky Anywhere on the Web ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Doubting Haskell
Concerning the Haskell program that does some statistics and displays some graphs, I must say that if that were the task I had to solve I would not use either C++ or Haskell, but R, the open source S lookalike. The best way to be productive as a programmer is to not write code if you can steal it. R looks like an imperative language, but it is "value-oriented" in the same way that SETL is, so is by some criteria a functional language of sorts. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Functional programmer's intuition for adjunctions?
G'day all. Quoting Derek Elkins <[EMAIL PROTECTED]>: Of course, this is a concrete example using basic ideas of programming and not some "intuitive analogy". I feel comfortable working with adjunctions, but I don't have some general analogy that I use. I think this is important. The concept of an adjunction isn't like that of a natural transformation. In Haskell, natural transformations are functions that respect the structure of functors. Since you can't avoid respecting the structure of functors (the language won't let you do otherwise), you get natural transformations for free. (Free as in theorems, not free as in beer.) Adjunctions, on the other hand, you have to make yourself. As such, they're more like monads. I use at least three distinct pictures when I'm working with monads: - Overloaded semicolon. - Functorial container (e.g. lists). - Term substitution system. ...but even that doesn't fully cover all the possibilities that monads give you. Monads are what they are, and you use them when it seems to make sense to implement the Monad interface for them. It's sometimes only obvious that an interface is conformed to after the event. For example, consider Data.Supply: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/value-supply-0.1 It's clear in retrospect that Supply is a comonad, but probably neither the paper authors nor the package author, smart as they are, noticed this at the time of writing, because you need experience with comonads to identify them. I think it's the same with adjunctions. Having said that, I think it makes sense to come up with some example pictures, much like the example pictures of monads that people use. Looking at those examples again: phi :: (F a -> b) -> (a -> U b) phiInv :: (a -> U b) -> (F a -> b) One thing that springs to mind is that an adjunction could connect monads and their associated comonads. Is that a good picture? Cheers, Andrew Bromage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Issues(Bugs?) with GHC Type Families
Just something I have been wondering. I would like to implement somehting like: type family F a :: * -> * ... class C a b where ... instance (F a ~ F b) => C a b where ... But apparently type equality coercions can not be used as a single context. If I enable -fallow-undecidable-instances, whenever the equality does not hold, the instance returns a compile error, what does make sense. Is there any way I could overcome this? Thanks, hugo ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Doubting Haskell
Thanks for an interesting write-up. And not bad for a first Haskell program. :) There's still a number of things you could do to limit the boiler plate code, though. On Tue, Mar 4, 2008 at 6:29 AM, Alan Carter <[EMAIL PROTECTED]> wrote: > Many thanks for the explanations when I was first experimenting with > Haskell. I managed to finish translating a C++ wxWidgets program into > Haskell wxHaskell, and am certainly impressed. > > I've written up some reflections on my newbie experience together with > both versions, which might be helpful to people interested in > popularizing Haskell, at: > > http://the-programmers-stone.com/2008/03/04/a-first-haskell-experience/ > > Regards, > > Alan > > -- > ... the PA system was moaning unctuously, like a lady hippopotamus > reading A. E. Housman ..." > -- James Blish, "They Shall Have Stars" > ___ > 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] Connection helpers: for people interested in network code
nominolo: > > On 5 mar 2008, at 22.05, Bjorn Bringert wrote: > > > >There is some (dormant?) work on bringing HTTP into the age of the > >ByteString. Thomas Schilling (nominolo) might be able to tell you more > >about it. > > > > Well, I can say with certainty that I won't have the time nor energy > to bring this into a usable state anytime soon (speak: not this > year). I think it's unlikely that Jonas will, either. Our work was > a quick hack, meant mainly as a proof of concept. Doing it well > would require work and more knowledge of the HTTP protocol than I > have, ATM. I agree that it would be valuable to the community, but > it's not gonna be me. > > I wonder, though, what happened to the curl bindings for Haskell? > This was a Summer of Code project last year. Also Johan Tibell > expressed some interest in getting bytestrings for HTTP. $ git clone http://code.haskell.org/curl.git :) But really, we want an no-errors bytestring-efficient http of our own. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Connection helpers: for people interested in network code
On 5 mar 2008, at 22.05, Bjorn Bringert wrote: There is some (dormant?) work on bringing HTTP into the age of the ByteString. Thomas Schilling (nominolo) might be able to tell you more about it. Well, I can say with certainty that I won't have the time nor energy to bring this into a usable state anytime soon (speak: not this year). I think it's unlikely that Jonas will, either. Our work was a quick hack, meant mainly as a proof of concept. Doing it well would require work and more knowledge of the HTTP protocol than I have, ATM. I agree that it would be valuable to the community, but it's not gonna be me. I wonder, though, what happened to the curl bindings for Haskell? This was a Summer of Code project last year. Also Johan Tibell expressed some interest in getting bytestrings for HTTP. / Thomas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Starting Haskell with a web application
On Wed, Mar 5, 2008 at 6:52 PM, Bryan O'Sullivan <[EMAIL PROTECTED]> wrote: > Jonathan Gardner wrote: > > > Where do I get started in writing a web app with Haskell? I am looking > > more for a framework like Pylons and less like Apache, if that helps. > > The closest we currently have to a web framework is Happs > (http://happs.org/), but it uses the kitchen sink of advanced and > unusual language extensions, which I think might be why it hasn't got > all that much momentum. > > There's also WASH, but that has an even lower profile. I couldn't tell > you if it sees much use, or even builds with recent compilers. > My web host has GHC 6.6 and it builds fine. I like WASH quite a lot, though it may be a bit heavy-weight for certain applications in the way it does sessions (though it works really well e.g. when users click the back button etc.). Maybe zipping up the session state or something would help there (or maybe it already does this?) - on my simple toy site it takes up around 30% of the total size, which is a bit hefty. Oh yeah, I use the preprocessor thing to get the nice syntax, but it's a bit messy when things go wrong since it passes through a preprocessor before being compiled. -- Sebastian Sylvan +44(0)7857-300802 UIN: 44640862 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Connection helpers: for people interested in network code
On Tue, Mar 4, 2008 at 5:15 PM, Adam Langley <[EMAIL PROTECTED]> wrote: > On Tue, Mar 4, 2008 at 7:31 AM, Bjorn Bringert <[EMAIL PROTECTED]> wrote: > > you may want to have a look at the socket abstraction used in the HTTP > package: > > > > > http://hackage.haskell.org/packages/archive/HTTP/3001.0.4/doc/html/Network-Stream.html > > > > It would be great to get HTTPS support going! > > I should have mentioned that I had seen this in the original email. I > think the major problem with this interface was that it was written in > the time before ByteStrings. Now that we have ByteStrings I think that > it makes a lot of sense for networking to use them. > > However, it shouldn't be too hard to wrap HsOpenSSL in this interface. > I might try this this week. Then HTTPS should Just Work (maybe ;) There is some (dormant?) work on bringing HTTP into the age of the ByteString. Thomas Schilling (nominolo) might be able to tell you more about it. /B ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Starting Haskell with a web application
On Wed, Mar 5, 2008 at 11:07 AM, Bryan O'Sullivan <[EMAIL PROTECTED]> wrote: > Indeed. In addition to the code you mention, people like Adam Langley > and Johan Tibbell are taking on corners of the web app problem space in > a more modern context. I should probably speak up then ;) I'm (slowly) writing Network.MiniHTTP. What it does have is a modern, ByteString based HTTP parser and serialiser (in decent shape), SSL support (only in darcs at the moment) and my test case, that I'm working towards, is an OpenID consumer. Once I have that working, I'll do a second release. It's not that far off, it's just a question of time. AGL -- Adam Langley [EMAIL PROTECTED] http://www.imperialviolet.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Starting Haskell with a web application
Don Stewart wrote: > Perhaps it is time for a haskell web apps wiki page, if there isn't one, > outlining the approaches, Indeed. In addition to the code you mention, people like Adam Langley and Johan Tibbell are taking on corners of the web app problem space in a more modern context. It's going to be an interesting year or two; I only wish we could accelerate the arrival of this particular portion of the future. We have a hole in "Real World Haskell" for writing about web development that we can't satisfactorily fill with what's currently available. http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Starting Haskell with a web application
bos: > Jonathan Gardner wrote: > > > Where do I get started in writing a web app with Haskell? I am looking > > more for a framework like Pylons and less like Apache, if that helps. > > The closest we currently have to a web framework is Happs > (http://happs.org/), but it uses the kitchen sink of advanced and > unusual language extensions, which I think might be why it hasn't got > all that much momentum. > > There's also WASH, but that has an even lower profile. I couldn't tell > you if it sees much use, or even builds with recent compilers. Perhaps it is time for a haskell web apps wiki page, if there isn't one, outlining the approaches, with a structure like: * HAppS * CGI - FastCGI * Database solutions - HDBC - Takusen * Templating - HStringTemplate * JSON rpc etc. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Starting Haskell with a web application
Jonathan Gardner wrote: > Where do I get started in writing a web app with Haskell? I am looking > more for a framework like Pylons and less like Apache, if that helps. The closest we currently have to a web framework is Happs (http://happs.org/), but it uses the kitchen sink of advanced and unusual language extensions, which I think might be why it hasn't got all that much momentum. There's also WASH, but that has an even lower profile. I couldn't tell you if it sees much use, or even builds with recent compilers. http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Starting Haskell with a web application
I am sure I am missing something obvious, but since the cafe is the place to ask stupid questions... I am getting more and more excited about Haskell as I learn more and more about it. Professionally, and as a hobby, I love working on web applications. Where do I get started in writing a web app with Haskell? I am looking more for a framework like Pylons and less like Apache, if that helps. I am sure someone has already done the homework on this, so a link will be fine. -- Jonathan Gardner [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Yhc] Yhc Web Service quietly opened for public testing
Justin, On 3/5/08, Justin Bailey <[EMAIL PROTECTED]> wrote: > Does this take a Haskell program and compile it to JavaScript? That's > pretty amazing. Yes, exactly. The two user interface programs, MainGUI and NewEntry were written in Haskell and compiled into Javascript by the same tools. With minimal changes they are pasteable/compilable by this service as well. See http://haskell.org/pipermail/yhc/2008-March/001194.html - anybody wants to try? I suggested this relatively simple program as a test example just to make sure results would be similar for everybody. More complex issues may arise e. g. with CSS interpreted differently by FF vs MSIE; this needs to work on in the future. Thanks for your interest. -- Dimitry Golubovsky Anywhere on the Web ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Yhc] Yhc Web Service quietly opened for public testing
> 2008/3/4, Dimitry Golubovsky <[EMAIL PROTECTED]>: > > Hi, > > > > I finally got the Yhc Web Service (web-based front end to the > > compiler) running in public testing mode. There hasn't been any > > documentation written, and Haddock stuff not brought in order, but if > > anyone wants to just get a taste of it, please open this hpaste entry: > > > > http://hpaste.org/6094 Does this take a Haskell program and compile it to JavaScript? That's pretty amazing. Justin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] 2nd CFP: PLMMS 2008
SECOND CALL FOR PAPERS * UPDATE: Post-workshop proceedings in Journal of Automated Reasoning * UPDATE: Invited talk by Conor McBride Second Workshop on Programming Languages for Mechanized Mathematics (PLMMS 2008) http://events.cs.bham.ac.uk/cicm08/workshops/plmms/ As part of CICM / Calculemus 2008 Birmingham, UK, 28-29 July 2008 This workshop is focused on the intersection of programming languages (PL) and mechanized mathematics systems (MMS). The latter category subsumes present-day computer algebra systems (CAS), interactive proof assistants (PA), and automated theorem provers (ATP), all heading towards fully integrated mechanized mathematical assistants that are expected to emerge eventually (cf. the objective of Calculemus). The two subjects of PL and MMS meet in the following topics, which are of particular interest to this workshop: * Dedicated input languages for MMS: covers all aspects of languages intended for the user to deploy or extend the system, both algorithmic and declarative ones. Typical examples are tactic definition languages such as Ltac in Coq, mathematical proof languages as in Mizar or Isar, or specialized programming languages built into CA systems. Of particular interest are the semantics of those languages, especially when current ones are untyped. * Mathematical modeling languages used for programming: covers the relation of logical descriptions vs. algorithmic content. For instance the logic of ACL2 extends a version of Lisp, that of Coq is close to Haskell, and some portions of HOL are similar to ML and Haskell, while Maple tries to do both simultaneously. Such mathematical languages offer rich specification capabilities, which are rarely available in regular programming languages. How can programming benefit from mathematical concepts, without limiting mathematics to the computational worldview? * Programming languages with mathematical specifications: covers advanced "mathematical" concepts in programming languages that improve the expressive power of functional specifications, type systems, module systems etc. Programming languages with dependent types are of particular interest here, as is intentionality vs extensionality. * Language elements for program verification: covers specific means built into a language to facilitate correctness proofs using MMS. For example, logical annotations within programs may be turned into verification conditions to be solved in a proof assistant eventually. How need MMS and PL to be improved to make this work conveniently and in a mathematically appealing way? These issues have a very colorful history. Many PL innovations first appeared in either CA or proof systems first, before migrating into more mainstream programming languages. Some examples include type inference, dependent types, generics, term-rewriting, first-class types, first-class expressions, first-class modules, code extraction etc. However, such innovations were never aggressively pursued by builders of MMS, but often reconstructed by programming language researchers. This workshop is an opportunity to present the latest innovations in MMS design that may be relevant to future programming languages, or conversely novel PL principles that improve upon implementation and deployment of MMS. We also want to critically examine what has worked, and what has not. Why are all the languages of mainstream CA systems untyped? Why are the (strongly typed) proof assistants so much harder to use than a typical CAS? What forms of polymorphism exist in mathematics? What forms of dependent types may be used in mathematical modeling? How can MMS regain the upper hand on issues of "genericity" and "modularity"? What are the biggest barriers to using a more mainstream language as a host language for a CAS or PA/ATP? Invited Talk Conor McBride (Alta Systems, Northern Ireland) will give an invited talk. Submission -- Submission works through EasyChair http://www.easychair.org/conferences/?conf=plmms2008 Two kinds of papers will be considered: * Full research papers may be up to 12 pages long. Authors of accepted papers are expected to present their work on the workshop in a regular talk. * Position papers may be up to 4 pages long. The workshop presentation of accepted position papers consists of two parts: a stimulating statement of certain issues or challenges by the author, followed by a discussion in the plenum. Papers should use the usual ENTCS style http://www.entcs.org/prelim.html (11 point version), and will be reviewed by the program committee. Informal workshop proceedings will be circulated as a technical report. Moreover there will be post-workshop proceedings of improved research papers, or position paper
[Haskell-cafe] Job opening: Use Haskell to save the environment!
Well - maybe¹. I'm not sure how relevant this is for this list, but I thought I should mention that there is an open position for a 3-year Ph.D. scolarship at IMR where I work. The work is in bioinformatics, and as I'm a happy Haskell user, I'd be happy to see qualified applicants who know Haskell as well. If you are interested, and posess a Master's degree (or equivalent education), a rough translation of the announcement is attached - the official one (in Norwegian) can be found at: http://www.imr.no/aktuelt/ledige_stillinger/stipendiat_bioinformatikk, Please contact me with any questions! -k There is an open research fellow position (Ph.D. scholarship) at the Institute of Marine Research in Bergen, Norway. The position is for three years, and it is part of the project "Salmon louse genome sequencing and functional studies on host parasite interactions", financed by the Norwegian Research Council's program for functional genomics, FUGE. The sea louse is an important ecological and economic problem for the fish farming industry, and the goal of the project is to investigate parasite-host interactions, ultimately leading to a vaccine against the sea louse. The research fellow will contribute to annotation and other analysis of sequence data, establishing improved models for errors, and development of new methods and software tools for computational analysis. New sequencing technologies are likely to be central. We are looking for a motivated candidate with a relevant master's degree or equivalent education, and a solid background in one of the following topics: * algorithm development and analysis * statistics * bioinformatics * molecular biology Place of work will be Bergen, the salary follows national regulations and starts out at NOK 325000 (i.e., approximately €4)/year. Contact Ketil Malde ([EMAIL PROTECTED], +47 55238647) for further details. ¹) The target of the project is the sea louse, which is a large ecological and economical problem. -- If I haven't seen further, it is by standing in the footprints of giants ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] Orphan instances
| GHC emits warning about orphan instance A (T t), since neither A nor T are | defined in B. However I can't move the instance to A or T since it depends | on B. Would it be fine to lift the restriction, such that it is accepted | to declare the instance in a module where the type or the class or a | superclass (this is new) is defined? The issue is this. Suppose GHC is compiling a module X, somewhere far away from the modules A,T,B which you define. While compiling X, GHC needs to solve the class constraint A (T Int) Well, in order to make sense of the constraint, GHC will have read the interfaces for module A and T, so that it knows that A is indeed a class, and T is indeed a type constructor. But so far nothing says that it needs to read the interface for B. But suppose that B indeed appears in the transitive closure of X's imports. Then the programmer expects GHC to find the instance in B. To ensure that it does, GHC reads the interface of every orphan module in the transitive closure of X's imports. (An orphan module is one like B that defines an instance whose head does not mention something defined locally.) The warning is just so that you know this is going to happen. It's something to avoid when unnecessary, but not a bug. I think you can see from this explanation that simply declaring that B isn't an orphan module after all isn't going to help! Simon | -Original Message- | From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Henning Thielemann | Sent: 05 March 2008 06:53 | To: Haskell Cafe | Subject: [Haskell-cafe] Orphan instances | | | Consider the following modules | | | module A | | class A t | | | module T | | import A | | data T a | | | module B | | import A | import T | | class A t => B t | | instance B t => A (T t) | | | | GHC emits warning about orphan instance A (T t), since neither A nor T are | defined in B. However I can't move the instance to A or T since it depends | on B. Would it be fine to lift the restriction, such that it is accepted | to declare the instance in a module where the type or the class or a | superclass (this is new) is defined? | | | In my example class B provides conversion toInteger (that is Integral), | class A provides conversion toRational (that is Real) and T is Ratio. | ___ | Haskell-Cafe mailing list | Haskell-Cafe@haskell.org | http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Exporting Haskell Libraries to C Programmers
Bruce, Joseph R (Joe) wrote: [snip] I hadn't looked at CABAL before. It's a very useful tool and met all my library-forming needs. That's only half my problem though. I'm trying to make the use of this Haskell code as transparent as possible to the C programmers on the team. Telling them about the Haskell base libraries dependency or distributing those libraries with my code is not too bad, but the list of -u flags that the linker needs is brutal. Is there a way to avoid it, or embed it in the package? Ex (using ghc-6.8.2 -v): ... gcc -v -o primes Primes.o ./Primes_stub.o hs_primes_wrapper.o cprimes.c [snip] Maybe try compiling cprimes.c to cprimes.o with gcc, then link with GHC? Something like: gcc -o cprimes.o -c cprimes.c ghc -no-hs-main --make -c *.hs ghc -no-hs-main -package foo -o moo *.o I know this isn't ideal, but it's similar to what I used to build a .so from Haskell code that can be loaded by a C app ignorant of Haskell. Claude -- http://claudiusmaximus.goto10.org ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: ANN: Takusen 0.8
> Changes since 0.6: > > - ODBC support. This still has a few gaps (and probably bugs and rough > edges) >but should be fairly usable. Doh! I had also meant to make a request: the ODBC code (and Setup.hs configuration) is only tested under Windows (XP). We'd love for people to test on *nix platforms and fill in the missing bits in the Setup script. Alistair ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANN: Takusen 0.8
Oleg and I are pleased to announce the release of Takusen 0.8. (Don Stewart did an interim 0.7 release for us a few weeks ago, and added us to Hackage. This release is a tidy-up of some loose ends, and some bug fixes. Hence, I've summarise the changes since the 0.6 release.) Changes since 0.6: - ODBC support. This still has a few gaps (and probably bugs and rough edges) but should be fairly usable. - support for reusable/persistent sessions, so you can hang onto the connection object between invocations of withSession (this was in release 0.6 but omitted from the release notes). - improvements to the Cabal Setup scripts, which should give better experiences for ghc-6.4, ghc-6.6, and ghc-6.8. The (eventual) 1.4 release of Cabal should be able to build our haddock docs, too. - improved UTF8 decoder (marshals directly from buffer). The release bundle: http://hackage.haskell.org/packages/archive/Takusen/0.8/Takusen-0.8.tar.gz The latest code: darcs get http://darcs.haskell.org/takusen Docs: http://darcs.haskell.org/takusen/doc/html/index.html A comprehensive description of API usage can be found in the documentation for module Database.Enumerator (look for the Usage section): http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.html Future plans: - FreeTDS backend (Sybase and MS Sql Server) - support for Blobs and Clobs For those of you unfamiliar with Takusen, here is our HCAR blurb: Takusen is a library for accessing DBMS's. Like HSQL, we support arbitrary SQL statements (currently strings, extensible to anything that can be converted to a string). Takusen's `unique-selling-point' is safety and efficiency. We statically ensure all acquired database resources - such as cursors, connection and statement handles - are released, exactly once, at predictable times. Takusen can avoid loading the whole result set in memory, and so can handle queries returning millions of rows in constant space. Takusen also supports automatic marshalling and unmarshalling of results and query parameters. These benefits come from the design of query result processing around a left-fold enumerator. Currently we fully support ODBC, Oracle, Sqlite, and PostgreSQL. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
