Re: [Haskell-cafe] Terminology
* Emmanuel Castro emmanuel.cas...@laposte.net [2010-06-15 00:10:09+0200] I am looking for the name of the property linking two functions f and g when : [f(a),f(b),f(c)] = g([a,b,c]) Is there a standard name? In practice, g is an optimised version of f when working on large amount of elements. Sometimes (particularly in Data Parallel Haskell, but also in other languages) 'g' is called vectorized version of 'f'. -- Roman I. Cheplyaka :: http://ro-che.info/ Don't let school get in the way of your education. - Mark Twain ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
braver delivera...@gmail.com writes: In fact, the tag cafe2, when run on the full dataset, gets stuck at 11 days, with RAM slowly getting into 50 GB One tip might be to limit available heap memory by using +RTS -M2G (or whatever your real memory is). If (as seems likely) the RAM usage leads to thrashing (the symptoms being 'top' showing substantially less than 100% CPU usage, and a less responsive system), limiting heap will cause your program to fail faster, which is always an advantage when debugging. Unless you actually expect the working set to be fifty gig, that is. -k -- 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] How to browse code written by others
On 15.06.2010, at 01:35, Luke Palmer wrote: On Mon, Jun 14, 2010 at 2:02 AM, Jean-Marie Gaillourdet j...@gaillourdet.net wrote: Hello, On 13.06.2010, at 22:32, Martin Drautzburg wrote: I need your advice about how to browse code which was written by someone else (Paul Hudak's Euterpea, to be precise, apx. 1 LOC). I had set some hopes on leksah, and it indeed shows me the interfaces, but I have not yet convinced it to show me more than that. I ran haddock over the sources, and again I could not see more that just signatures. I would be very happy with something like a Smalltalk browser. Something that would let me zoom down to the source code, but with search and hyperlink capabilities (senders and implementers in Smalltalk). Anyways, how do you guys do it, i.e. how to you dive into non-trivial foreign code? I use the following tools: * haddock generated docs with hyperlinked sources * MacVim (or just vim) with Claus Reinke's haskellmode-vim, see: http://projects.haskell.org/haskellmode-vim/index.html Have a look at the screencasts to see documentation lookup, and code navigation: http://projects.haskell.org/haskellmode-vim/screencasts.html Make sure you know how to use tags inside of vim. ghci is able to generate the tagsfiles for you. This allows you to jump to definitions of identifiers. If you go this route, I will shamelessly promote hothasktags instead of ghci. It generates proper tags for qualified imports. That sounds interesting. Thanks for the hint. Regards, Jean-Marie___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haddock Problem
David Waern david.waern at gmail.com writes: I think using --optghc=-package-conf is the correct way to point to another package DB, so I'll look into why it doesn't work. Perhaps another line of attack would be to see why haddock thinks I have an E: drive? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Indonesia
Hi, I'm new in Haskell wondering is there Indonesian people using Haskell here. Nice meet* you all :) Regards, vipex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Accounting Engine in Haskell
My current project is about making an accounting engine that handles all the journal entries, transactions, portfolios etc. The communication with the engine is based on simple protocol, the things to be taken care of in the order are consistency, handling large data(performance) and availability. I came across a video lecture by Simon Peyton Jones where he gives an example from Financial domain (derivatives etc) to explain how haskell is being used and the advantages provided. I am interested in knowing if Haskell will be the right fit for my project. My requirements are transactional nature, which I believe is one of the strengths of functional programming, also handling large data set and being available. there is no such requirement for partitioning of data and the application is going to be centrally hosted on a single server. AFAIK OCaml and other functional languages are heavily used in financial domain, some of the reason are same as features I am looking for. I wanted some insight as to how Haskell is going to help me with my project. Also there has been some concerns because of lazy evaluation in Haskell and memory leaks associated with it. http://jlouisramblings.blogspot.com/2010/04/haskell-vs-erlang-for-bittorent-clients.html Also, if you have any suggestions of the choice of programming language, we have been looking into other functional languages like Scala and Clojure. But we have not dig deep on the performance aspects of these languages, if someone can shed a light on the pros- cons of these languages, it will help us very much to come to a decision. -Regards, Amir ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell-beginners] Accounting Engine in Haskell
I don't think I can be of much help with regards to the questions, but would you be able to post a link to the SPJ lecture? Thanks :-) On Tue, Jun 15, 2010 at 4:08 PM, Amiruddin Nagri amir.na...@gmail.com wrote: My current project is about making an accounting engine that handles all the journal entries, transactions, portfolios etc. The communication with the engine is based on simple protocol, the things to be taken care of in the order are consistency, handling large data(performance) and availability. I came across a video lecture by Simon Peyton Jones where he gives an example from Financial domain (derivatives etc) to explain how haskell is being used and the advantages provided. I am interested in knowing if Haskell will be the right fit for my project. My requirements are transactional nature, which I believe is one of the strengths of functional programming, also handling large data set and being available. there is no such requirement for partitioning of data and the application is going to be centrally hosted on a single server. AFAIK OCaml and other functional languages are heavily used in financial domain, some of the reason are same as features I am looking for. I wanted some insight as to how Haskell is going to help me with my project. Also there has been some concerns because of lazy evaluation in Haskell and memory leaks associated with it. http://jlouisramblings.blogspot.com/2010/04/haskell-vs-erlang-for-bittorent-clients.html Also, if you have any suggestions of the choice of programming language, we have been looking into other functional languages like Scala and Clojure. But we have not dig deep on the performance aspects of these languages, if someone can shed a light on the pros- cons of these languages, it will help us very much to come to a decision. -Regards, Amir ___ Beginners mailing list beginn...@haskell.org http://www.haskell.org/mailman/listinfo/beginners ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] learning advanced haskell
Thanks for the great responses. My haskell-learning todo list is refreshed and renewed :) I would point out, though, that had I followed a Learn when needed philosophy more broadly I would never have come to Haskell or even functional programming in general. Aran On Mon, Jun 14, 2010 at 12:33 PM, Andrew Coppin andrewcop...@btinternet.com wrote: John Lato wrote: I sort of agree with this, with some very large caveats. Well, yes. If you don't know what a feature does, then you won't know that it solves the problem you have. However, there's a lot to be said for both intellectual curiosity and learning for the sake of knowledge. Just because you may never need to use a feature doesn't mean you shouldn't be able to understand it. There is that. However, in my experience, most of the advanced techniques tend to be described in language beyond my comprehension. (And most examples seem overly complex - although maybe that's just a reflection of the fact that simple problems don't require sophisticated techniques in the first place.) Having a specific problem to solve can be quite helpful. Unlike an example, you already understand what the problem is, and why it can't easily be solved any other way. ___ 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] Re: [Haskell-beginners] Accounting Engine in Haskell
It should be somewhere here - http://www.haskell.org/haskellwiki/Video_presentations -Amir On Tue, Jun 15, 2010 at 1:42 PM, Lyndon Maydwell maydw...@gmail.com wrote: I don't think I can be of much help with regards to the questions, but would you be able to post a link to the SPJ lecture? Thanks :-) On Tue, Jun 15, 2010 at 4:08 PM, Amiruddin Nagri amir.na...@gmail.com wrote: My current project is about making an accounting engine that handles all the journal entries, transactions, portfolios etc. The communication with the engine is based on simple protocol, the things to be taken care of in the order are consistency, handling large data(performance) and availability. I came across a video lecture by Simon Peyton Jones where he gives an example from Financial domain (derivatives etc) to explain how haskell is being used and the advantages provided. I am interested in knowing if Haskell will be the right fit for my project. My requirements are transactional nature, which I believe is one of the strengths of functional programming, also handling large data set and being available. there is no such requirement for partitioning of data and the application is going to be centrally hosted on a single server. AFAIK OCaml and other functional languages are heavily used in financial domain, some of the reason are same as features I am looking for. I wanted some insight as to how Haskell is going to help me with my project. Also there has been some concerns because of lazy evaluation in Haskell and memory leaks associated with it. http://jlouisramblings.blogspot.com/2010/04/haskell-vs-erlang-for-bittorent-clients.html Also, if you have any suggestions of the choice of programming language, we have been looking into other functional languages like Scala and Clojure. But we have not dig deep on the performance aspects of these languages, if someone can shed a light on the pros- cons of these languages, it will help us very much to come to a decision. -Regards, Amir ___ Beginners mailing list beginn...@haskell.org http://www.haskell.org/mailman/listinfo/beginners ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] learning advanced haskell
Message: 7 Date: Mon, 14 Jun 2010 20:33:30 +0100 From: Andrew Coppin andrewcop...@btinternet.com Subject: Re: [Haskell-cafe] learning advanced haskell To: haskell-cafe@haskell.org Message-ID: 4c16840a.7060...@btinternet.com Content-Type: text/plain; charset=ISO-8859-1; format=flowed John Lato wrote: However, there's a lot to be said for both intellectual curiosity and learning for the sake of knowledge. Just because you may never need to use a feature doesn't mean you shouldn't be able to understand it. There is that. However, in my experience, most of the advanced techniques tend to be described in language beyond my comprehension. (And most examples seem overly complex - although maybe that's just a reflection of the fact that simple problems don't require sophisticated techniques in the first place.) Having a specific problem to solve can be quite helpful. Unlike an example, you already understand what the problem is, and why it can't easily be solved any other way. Yes, having a specific problem to solve can be very helpful. The OP requested examples of them. I'd like to see them myself, partially as a reference but mostly to satisfy my own curiosity. More examples please! John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: [Haskell-beginners] Accounting Engine in Haskell
Hi Amir, Amiruddin Nagri wrote: My current project is about making an accounting engine... Take a look at the related but different project hledger. http://hackage.haskell.org/package/hledger http://hackage.haskell.org/package/hledger-lib consistency, handling large data(performance) and availability... I am interested in knowing if Haskell will be the right fit for my project. These things can certainly be achieved, and Haskell is a great platform for it. Reliability and assurance of correctness are very important for financial systems, and Haskell is especially good at providing them together with good performance. However, keep in mind that you are undertaking a very ambitious project. There are a lot of little design decisions to be made along the way which, if made without a lot of previous experience in whatever language you are using, could lead to serious problems later on in a large system like this. I recommend: o Start with a less ambitious version of the project - a simpler prototype with less requirements, or components that can be developed as a stand-alone and later integrated into your larger system. o Work closely with the community, on the #haskell IRC channel and the Haskell Cafe mailing list, to get guidance from experienced Haskellers. Share and discuss your code as you go along. (Or, if you select a different language that you are not very experienced in for developing large high-assurance commercial systems, do the same with that language's community.) Also there has been some concerns because of lazy evaluation in Haskell and memory leaks associated with it. The possibility for memory and performance leaks in large systems written in Haskell is no more or less than in any other mature programming language. As in any language, it takes experience and care to avoid them as your application scales up. Good luck, Yitz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Problems with threading?
On 12/06/2010 02:48, Don Stewart wrote: igouy2: parallel, regex-posix, regex-pcre are now installed and the current compile errors are caused by the programs not the absence of required libraries - http://shootout.alioth.debian.org/u64q/program.php?test=binarytreeslang=ghcid=2#log http://shootout.alioth.debian.org/u64q/program.php?test=binarytreeslang=ghcid=3#log http://shootout.alioth.debian.org/u64q/program.php?test=regexdnalang=ghcid=4#log http://shootout.alioth.debian.org/u64q/program.php?test=regexdnalang=ghcid=1#log Great work! For those keen to help out the Haskell programs, both compile failures in regexdna and binarytrees are related to the change in how parallel strategies work, as described here. http://hackage.haskell.org/packages/archive/parallel/2.2.0.1/doc/html/Control-Parallel-Strategies.html Change rnf to rdeepseq, that should fix it. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
On 15/06/2010 06:09, braver wrote: In fact, the tag cafe2, when run on the full dataset, gets stuck at 11 days, with RAM slowly getting into 50 GB; a previous version caused ghc 6.12.1 to segfault around day 12 -- -debug showing an assert failure in Storage.c. ghc 6.10 got stuck at 30 days for good, and when profiling crashed twice with a strange closure or a stack overflow. So allocation is a problem still. I'd be happy to help you track this down, but I don't have a machine big enough. Do you have any runs that display a problem with a smaller heap ( 16GB)? If the program is apparently hung, try connecting to it with 'gdb --pid=pid' and doing 'info thread' and 'where'. That might give me enough clues to find out where the problem is. Is this with -threaded, BTW? With residency on that scale, I'd expect the parallel GC to help quite a lot. But obviously getting it to not crash/hang is the first priority :) Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Mining Twitter data in Haskell and Clojure
Op 14-06-10 07:00, braver schreef: I'm computing a communication graph from Twitter data and then scan it daily to allocate social capital to nodes behaving in a good karmic manner. The graph is culled from 100 million tweets and has about 3 million nodes. First I wrote the simulation of the 35 days of data in Clojure and then translated it into Haskell with great help from the glorious #haskell folks. I had to add -A5G -K5G to make it work. It does 10 days OK hovering at 57 GB of RAM; I include profiling of that in sc10days.prof. At first the Haskell executable goes faster than Clojure, not by an order of magnitude, but by 2-3 times per day simulated. (Clojure also fits well in its 32 GB JVM with compressed references.) However, Haskell gets stuck after a while, and for good. Clearly I'm not doing Haskell optimally here, and would appreciate optimization advice. Here's the code: http://github.com/alexy/husky The data and problem description is in http://github.com/alexy/husky/blob/master/Haskell-vs-Clojure-Twitter.md -- also referred from the main README.md. The main is in sc.hs, and the algorithm is in SocRun.hs. The original Clojure is in socrun.clj. This is a continuation of active Twitter research and the results will be published, and I'd really like to make Haskell work at this scale and beyond! The seq's sprinkled already did no good. I ran under ghc 6.10 with -O2 with or without - fvia-C, with no difference in stallling, and am working to bring 6.12 to bear now. Cheers, Alexy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe If you just want to optimize it and not compare exactly equal idiomatic code, you should stop using functional data structures and use a structure that fits your problem (the ST monad has been designed for that in Haskell), because compilers do not detect single-threaded usage and rewrite all your code to something mutable and thereby avoid O(log n) costs. In practice it is probably easier to write the whole thing against the parallel Boost Graph Library (a C++ library), since that library provides the abstractions that you would want. If you go this path, it will probably end up being 10-100 times faster. -- Best Regards, Ron de Bruijn, ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Indonesia
I'm one of them :) Nice to meet you... vipex.id wrote: Hi, I'm new in Haskell wondering is there Indonesian people using Haskell here. Nice meet* you all :) Regards, vipex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- View this message in context: http://old.nabble.com/Haskell-Indonesia-tp2215p28889986.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
Re: [Haskell-cafe] Re: Haddock Problem
2010/6/15 Dominic Steinitz domi...@steinitz.org: David Waern david.waern at gmail.com writes: I think using --optghc=-package-conf is the correct way to point to another package DB, so I'll look into why it doesn't work. Perhaps another line of attack would be to see why haddock thinks I have an E: drive? Right. However I suspect it's not a problem with Haddock but rather something to do with the platform. David ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Terminology
Hello Emmanuel, Tuesday, June 15, 2010, 2:10:09 AM, you wrote: [f(a),f(b),f(c)] = g([a,b,c]) it looks a bit like vectorisation transformation in compilers -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Haddock Problem
2010/6/15 David Waern david.wa...@gmail.com: 2010/6/15 Dominic Steinitz domi...@steinitz.org: David Waern david.waern at gmail.com writes: I think using --optghc=-package-conf is the correct way to point to another package DB, so I'll look into why it doesn't work. Perhaps another line of attack would be to see why haddock thinks I have an E: drive? Right. However I suspect it's not a problem with Haddock but rather something to do with the platform. Here's something similar: http://trac.haskell.org/haskell-platform/ticket/119 I tried myself on windows, and haddock --print-ghc-libdir yields: E:\ghc\ghc-6.12.1\lib and I don't have an E: either. So Haddock seems to be more or less broken on windows in the current platform. David ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haddock Problem
I haven't been following closely, but how did you install haddock? From a binary dist? Is it possible that one of the Windows binary dists has a "baked-in" location for something on the E: drive, which existed on the packager's machine but not on the final installed machine?Regards, MalcolmOn 15 Jun, 2010,at 08:12 AM, Dominic Steinitz domi...@steinitz.org wrote:David Waern david.waern at gmail.com writes: I think using --optghc=-package-conf is the correct way to point to another package DB, so I'll look into why it doesn't work. Perhaps another line of attack would be to see why haddock thinks I have an "E:" drive? ___ 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] Haddock Problem
Hello all I don't know if this helps at all, but for a GHC 6.12.1 installed from the ghc-installer rather than HP I get: Cygwin prompt on WinXP... $ ./haddock.exe --print-ghc-libdir C:\ghc\ghc-6.12.1\bin\..\lib There is actually no corresponding *lib* directory, but haddock still works fine. Best wishes Stephen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haddock Problem
On 15 June 2010 15:13, Stephen Tetley stephen.tet...@gmail.com wrote: There is actually no corresponding *lib* directory, but haddock still works fine. This is a mistake on my part - I do have a corresponding lib directory which includes a package.conf.d directory - for GHC-6.12.1 (I was looking at the directory tree for 6.10.1 when I wrote the last message). Apologies. Stephen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Different choice operations in a continuation monad
Dear Café, `MonadPlus` instances are usually required to satisfy certain laws, among them the monad laws and monoid laws for `mzero` and `mplus`. Additionally one may require that (=f) is a monoid morphism, that is: mzero = f = mzero (a `mplus` b) = f = (a = f) `mplus` (b = f) The list monad satisfies these additional laws, the `Maybe`-Monad does not satisfy the second, distributive, law: ghci (return False `mplus` return True) = guard :: [()] [()] ghci (return False `mplus` return True) = guard :: Maybe () Nothing Instead of the distributive law, the `Maybe` monad satisfies a different law: return x `mplus` a = return x that is, `return` annihilates the `Maybe`-Monad regarding `mplus`. This cancellation law is incompatible with the distributive law because (together with other laws) it implies that the result of the above example expression is `Nothing` whereas the distributive law implies that it is `Just ()`. We can lift the `Maybe` type into a continuation monad: newtype CMaybe r a = CMaybe ((a - Maybe r) - Maybe r) instance Monad (CMaybe r) where return x= CMaybe (\k - k x) CMaybe ca = f = CMaybe (\k - ca (\x - let CMaybe cb = f x in cb k)) instance MonadPlus (CMaybe r) where mzero = CMaybe (\_ - mzero) CMaybe ca `mplus` CMaybe cb = CMaybe (\k - ca k `mplus` cb k) Unlike the `Maybe`-monad, the `CMaybe`-monad satisfies the distributive law, not the cancellation law. Can you define an associative operation orElse :: CMaybe r a - CMaybe r a - CMaybe r a with identity `mzero` that satisfies the cancellation law? Cheers, Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell Indonesia
Its not indonesia, but the Singapore FP Users is pretty close by. We aren't limited to just Haskell but there are several haskellers in the group. If you'd like to join us, drop an email to: singapore-functional-programm...@googlegroups.com Max On Jun 15, 2010, at 7:11 PM, leledumbo wrote: I'm one of them :) Nice to meet you... vipex.id wrote: Hi, I'm new in Haskell wondering is there Indonesian people using Haskell here. Nice meet* you all :) Regards, vipex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- View this message in context: http://old.nabble.com/Haskell-Indonesia-tp2215p28889986.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 mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: [Haskell-beginners] Accounting Engine in Haskell
I think Haskell would be an excellent choice. Several reasons come to mind: Given the arbitrary complexity of such projects, an EDSL describing book entries etc would be a very good fit for the project. As people have said once or twice, Haskell is a great fit for EDSLs If you want to get ambitious and scale this up to a multithreaded, multiuser environment, STM would be a very good concurrency model. This pretty much just leaves Haskell or Clojure. Finally, the type system of haskell is hugely useful to this project. Jane Street Capital (ocaml users and damned good at it) has a programming motto: make illegal transactions unrepresentative. The type systems of Haskell and OCaml let you structure this kind of project in a way to catch most of your bugs at compile time. So, I think Haskell is the perfect intersection of EDSL support, Concurrency, and powerful, static typing for the project. Good luck, keep us informed of your progress. Max On Jun 15, 2010, at 5:34 PM, Yitzchak Gale wrote: Hi Amir, Amiruddin Nagri wrote: My current project is about making an accounting engine... Take a look at the related but different project hledger. http://hackage.haskell.org/package/hledger http://hackage.haskell.org/package/hledger-lib consistency, handling large data(performance) and availability... I am interested in knowing if Haskell will be the right fit for my project. These things can certainly be achieved, and Haskell is a great platform for it. Reliability and assurance of correctness are very important for financial systems, and Haskell is especially good at providing them together with good performance. However, keep in mind that you are undertaking a very ambitious project. There are a lot of little design decisions to be made along the way which, if made without a lot of previous experience in whatever language you are using, could lead to serious problems later on in a large system like this. I recommend: o Start with a less ambitious version of the project - a simpler prototype with less requirements, or components that can be developed as a stand-alone and later integrated into your larger system. o Work closely with the community, on the #haskell IRC channel and the Haskell Cafe mailing list, to get guidance from experienced Haskellers. Share and discuss your code as you go along. (Or, if you select a different language that you are not very experienced in for developing large high-assurance commercial systems, do the same with that language's community.) Also there has been some concerns because of lazy evaluation in Haskell and memory leaks associated with it. The possibility for memory and performance leaks in large systems written in Haskell is no more or less than in any other mature programming language. As in any language, it takes experience and care to avoid them as your application scales up. Good luck, Yitz ___ 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] How to browse code written by others
..ghci is able to generate the tagsfiles for you. This allows you to
jump to definitions of identifiers.
If you go this route, I will shamelessly promote hothasktags instead
of ghci. It generates proper tags for qualified imports.
What do you mean by proper here? GHCi has the information
needed to generate more detailed tags, but the tags file format
did not support much more detail last time I checked.
Tags for explicitly qualified names could be generated (and
probably should be), though that would interact with the default
identification of Haskell identifiers in Vim. But if you want to
resolve imports properly (or at least a bit better, such as adding
import qualified as support, or pointing unqualified uses to
the correct import), you need more support from the tags
mechanism.
There is a tags file format proposal here:
http://ctags.sourceforge.net/FORMAT
that does (among other scopes) suggest explicitly file-scoped
local tags
file: Static (local) tag, with a scope of the specified file.
When the value is empty, {tagfile} is used.
but in Vim 7.2 the help file still says
http://vimdoc.sourceforge.net/htmldoc/tagsrch.html#tags-file-format
The only other field currently recognized by Vim is file:
(with an empty value). It is used for a static tag.
If Vim somehow started supporting that extended file:scope
format without updating its docs, that would be good to know
(what version of Vim? where is this documented?).
Your suggested use-case for such a feature is interesting, but
we're getting into an area where live calls to a scope resolution
tool might make more sense. If one is willing to depend on
Vim's Python-binding, one could keep a GHCi session live
in the background, track the current file/module, and use the
:info -- Defined at output to find the correct definition.
Btw, GHCi's :browse! gives information on where available
names come from, which can be useful for resolving unqualified
names (which map is that?) in unknown code.
Claus
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Re: [Haskell-cafe] Different choice operations in a continuation monad
Hi Sebastian, Am 15.06.2010 um 17:06 schrieb Sebastian Fischer: Dear Café, `MonadPlus` instances are usually required to satisfy certain laws, among them the monad laws and monoid laws for `mzero` and `mplus`. Additionally one may require that (=f) is a monoid morphism, that is: mzero = f = mzero (a `mplus` b) = f = (a = f) `mplus` (b = f) The list monad satisfies these additional laws, the `Maybe`-Monad does not satisfy the second, distributive, law: ghci (return False `mplus` return True) = guard :: [()] [()] ghci (return False `mplus` return True) = guard :: Maybe () Nothing Instead of the distributive law, the `Maybe` monad satisfies a different law: return x `mplus` a = return x that is, `return` annihilates the `Maybe`-Monad regarding `mplus`. This cancellation law is incompatible with the distributive law because (together with other laws) it implies that the result of the above example expression is `Nothing` whereas the distributive law implies that it is `Just ()`. We can lift the `Maybe` type into a continuation monad: newtype CMaybe r a = CMaybe ((a - Maybe r) - Maybe r) instance Monad (CMaybe r) where return x= CMaybe (\k - k x) CMaybe ca = f = CMaybe (\k - ca (\x - let CMaybe cb = f x in cb k)) instance MonadPlus (CMaybe r) where mzero = CMaybe (\_ - mzero) CMaybe ca `mplus` CMaybe cb = CMaybe (\k - ca k `mplus` cb k) Unlike the `Maybe`-monad, the `CMaybe`-monad satisfies the distributive law, not the cancellation law. Can you define an associative operation orElse :: CMaybe r a - CMaybe r a - CMaybe r a with identity `mzero` that satisfies the cancellation law? No, because that function would need to cancel values of type a, but the arguments of type (CMaybe r a) can only compute values of type r. But you can define orElse :: CMaybe a a - CMaybe a a - CMaybe r a CMaybe ca `orElse` CMaybe cb = CMaybe (\k - (ca return `mplus` cb return) = k) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Different choice operations in a continuation monad
Hello Holger, Can you define an associative operation orElse :: CMaybe r a - CMaybe r a - CMaybe r a with identity `mzero` that satisfies the cancellation law? No, because that function would need to cancel values of type a, but the arguments of type (CMaybe r a) can only compute values of type r. I'm afraid, I don't understand. But you can define orElse :: CMaybe a a - CMaybe a a - CMaybe r a CMaybe ca `orElse` CMaybe cb = CMaybe (\k - (ca return `mplus` cb return) = k) Good point. But with this restricted type `orElse` is less useful. For example, one cannot compute fromCMaybe ((return False `orElse` return True) = guard) because there, the arguments of `orElse` are of type `CMaybe () Bool`. Cheers, Sebastian P.S. fromCMaybe :: CMaybe a a - Maybe a fromCMaybe (CMaybe ca) = ca Just -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Different choice operations in a continuation monad
On Jun 15, 2010, at 6:11 PM, Sebastian Fischer wrote: orElse :: CMaybe a a - CMaybe a a - CMaybe r a CMaybe ca `orElse` CMaybe cb = CMaybe (\k - (ca return `mplus` cb return) = k) Good point. But with this restricted type `orElse` is less useful. For example, one cannot compute fromCMaybe ((return False `orElse` return True) = guard) because there, the arguments of `orElse` are of type `CMaybe () Bool`. Silly me! It's not the type of the *arguments* which is `CMaybe () Bool` but the type of the *result* of `orElse`, which is perfectly possible with your implementation! The type may be general enough. Interesting twist! I still don't understand why it is impossible to provide `orElse` with the original type. I will think more about the reason you gave. Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Vague: Assembly line process
On Tuesday, 15. June 2010 01:40:03 Luke Palmer wrote: So hang on, what is the problem? You have described something like a vague model, but what information are you trying to get? Say, perhaps, a set of possible output lists from a given input list? When I know my supplies I want to know what I can produce. When I know what I want to produce I want to know what supplies I need for that. Both kinds of questions should be answered by a singe Process thingy. I want to be able to chain processes and the whole thing should still act like a Process. Luke On Mon, Jun 14, 2010 at 11:16 AM, Martin Drautzburg martin.drautzb...@web.de wrote: Hello all, this is a problem which has haunted me for some time. If this is simply hillarious, please tell me so. Or it may be some well known unsolvable problem... An assembly process takes inputs and produces outputs. I could say a Process is a function canProduce :: [Input]-[Output]-Bool which tells me if the outputs can be produced from the inputs There may be a similar function which tells me if the inputs are completely consumed to procude the output. The inputs do not determine the exact outputs. Think of a Process which combines a List of Ints into pairs, such that the input ints are consumed and each input Int occurs in only one position in the output. There are many ways to do this. Still for any set of input Ints and output pairs I could decide if the output can be produced from the input. Likewise the Input is not determined by the output. There may be lots of choices from what I could build my output (buy from different vendors). When I know more about the inputs and outputs my choices get more and more limited. I would like to to pass inputs and/or outputs to something and I would like to get a something which is more restricted, but still essentially a thing which tells me if the outputs can be produced from the inputs. I just cannot find a way to even THINK about this problem in a reasonable general way. -- Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Martin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Vague: Assembly line process
On Tue, 15 Jun 2010 19:23:35 +0200, you wrote: When I know my supplies I want to know what I can produce. When I know what I want to produce I want to know what supplies I need for that. Both kinds of questions should be answered by a singe Process thingy. I want to be able to chain processes and the whole thing should still act like a Process. This is a type of constraint network. If you have access to _Structure and Interpretation of Computer Programs_, there is a section therein devoted to constraint networks. See also: http://en.wikipedia.org/wiki/Constraint_programming Note that you need to be able to handle two kinds of chaining: compoundContraint = constraint1 AND constraint2 -- the compound constraint isn't satisfied unless you can satisfy -- both primary constraints compoundContraint = constraint1 OR constraint2 -- the compound constraint is satisfied if either of the primary -- constraints is satisfied -Steve ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
If you just want to optimize it and not compare exactly equal idiomatic code, you should stop using functional data structures and use a structure that fits your problem (the ST monad has been designed for that in Haskell), because compilers do not detect single-threaded usage and rewrite all your code to something mutable and thereby avoid O(log n) costs. In practice it is probably easier to write the whole thing against the parallel Boost Graph Library (a C++ library), since that library provides the abstractions that you would want. If you go this path, it will probably end up being 10-100 times faster. Surely I can rewrite it in C++ or just C and gain speedup, but not maintainability and ease of prototyping algorithms -- the main reasons I switched to FP, with added reliability, conciseness, reasonable syntax bonuses. It turned out Clojure is quite capable of doing it well, but has Null Pointer Exceptions and debug data shape by running annoying to an ML programmer; trying Haskell for speedup is worth it! It proves less predictable than expected -- e.g. with OCaml if it typechecks and runs, it usually runs fast. The point of this exercise is to identify typical performance bottlenecks in the domain and see how they can be avoided. The jury's still out on this one. -- Alexy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
deliverable: If you just want to optimize it and not compare exactly equal idiomatic code, you should stop using functional data structures and use a structure that fits your problem (the ST monad has been designed for that in Haskell), because compilers do not detect single-threaded usage and rewrite all your code to something mutable and thereby avoid O(log n) costs. In practice it is probably easier to write the whole thing against the parallel Boost Graph Library (a C++ library), since that library provides the abstractions that you would want. If you go this path, it will probably end up being 10-100 times faster. Surely I can rewrite it in C++ or just C and gain speedup, but not maintainability and ease of prototyping algorithms -- the main reasons I switched to FP, with added reliability, conciseness, reasonable syntax bonuses. It turned out Clojure is quite capable of doing it well, but has Null Pointer Exceptions and debug data shape by running annoying to an ML programmer; trying Haskell for speedup is worth it! It proves less predictable than expected -- e.g. with OCaml if it typechecks and runs, it usually runs fast. The point of this exercise is to identify typical performance bottlenecks in the domain and see how they can be avoided. The jury's still out on this one. Following the algorithm for performance tuning in the previous email should be enough. Have you obtained heap profiles yet? -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Vague: Assembly line process
On Tue, Jun 15, 2010 at 7:23 PM, Martin Drautzburg
martin.drautzb...@web.de wrote:
When I know my supplies I want to know what I can produce. When I know what I
want to produce I want to know what supplies I need for that. Both kinds of
questions should be answered by a singe Process thingy.
Your Process thingy reminds me of a natural isomorphism:
data Iso a b = Iso { ab :: a - b
, ba :: b - a
}
I want to be able to chain processes and the whole thing should still act like
a Process.
These isomorphisms can be chained together using the standard Category
method '.':
import qualified Control.Category as C
instance C.Category Iso where
id = Iso id id
Iso bc cb . Iso ab ba = Iso (bc . ab) (ba . cb)
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[Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
On Jun 15, 6:27 am, Simon Marlow marlo...@gmail.com wrote: On 15/06/2010 06:09, braver wrote: In fact, the tag cafe2, when run on the full dataset, gets stuck at 11 days, with RAM slowly getting into 50 GB; a previous version caused ghc 6.12.1 to segfault around day 12 -- -debug showing an assert failure in Storage.c. ghc 6.10 got stuck at 30 days for good, and when profiling crashed twice with a strange closure or a stack overflow. So allocation is a problem still. I'd be happy to help you track this down, but I don't have a machine big enough. Do you have any runs that display a problem with a smaller heap ( 16GB)? If the program is apparently hung, try connecting to it with 'gdb --pid=pid' and doing 'info thread' and 'where'. That might give me enough clues to find out where the problem is. Is this with -threaded, BTW? With residency on that scale, I'd expect the parallel GC to help quite a lot. But obviously getting it to not crash/hang is the first priority :) Simon - thanks for the tips, this is what gdb says when it's stuck at 45 GB when limited with -A5G -M40G: ... 0x004c3c21 in free_mega_group () (gdb) info thread * 1 Thread 0x2b21c1da4dc0 (LWP 10210) 0x004c3c21 in free_mega_group () (gdb) where #0 0x004c3c21 in free_mega_group () #1 0x004c3ff9 in freeChain () #2 0x004c5ab0 in GarbageCollect () #3 0x004bff96 in scheduleDoGC () #4 0x004c0b25 in scheduleWaitThread () #5 0x004bea09 in real_main () #6 0x004beb17 in hs_main () #7 0x0037d5a1d974 in __libc_start_main () from /lib64/libc.so.6 #8 0x00402ca9 in _start () I'll also supply heap profiles for small runs shortly. -- Alexy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] learning advanced haskell
On Mon, Jun 14, 2010 at 7:42 AM, Aran Donohue aran.dono...@gmail.com wrote: Hints? Tips? One thing that isn't mentioned yet is to read other peoples programs. I'm subscribed to the Hackage RSS feed[1]. I tend to read (at least) the package page of every package that gets uploaded to hackage. Whenever an interesting package comes a long I dig a little deeper. First I try to understand what problem the package is trying to solve. Then I see how the package is structured into modules. Finally when I notice some interesting module or function I read its documentation (which unfortunately almost never exists) and source code and try to understand how and why it is being implemented like it is. Regards, Bas [1] http://hackage.haskell.org/packages/archive/recent.rss ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Different choice operations in a continuation monad
Sebastian Fischer wrote: Holger Siegel wrote: orElse :: CMaybe a a - CMaybe a a - CMaybe r a CMaybe ca `orElse` CMaybe cb = CMaybe (\k - (ca return `mplus` cb return) = k) I still don't understand why it is impossible to provide `orElse` with the original type. I will think more about the reason you gave. The reason is that you have chosen the wrong type for your continuation monad; it should be newtype CMaybe a = CMaybe (forall r. (a - Maybe r) - Maybe r) Personally, I recommend to stop thinking about continuations altogether and instead use the approach I've outlined in The Operational Monad Tutorial http://apfelmus.nfshost.com/articles/operational-monad.html to define and think about monads. In particular, performing the refunctionalization I mentioned in the subsection Connection with the Continuation Monad shows that the right type should indeed contain a forall r . Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
braver wrote: On Jun 14, 11:40 am, Don Stewart d...@galois.com wrote: Oh, you'll want insertWith'. You might also consider bytestring-trie for the Graph, and IntMap for the AdJList ? Yeah, I saw jsonb using Trie and thought there's a reason for it. But it's very API-poor compared with Map, e.g. there's not even a fold -- should one toListBy first? I find that surprising. Have you looked in Data.Trie.Convenience? The API of Data.Map is rather bloated so I've pushed most of it out of the main module in order to clean things up. There are only a small number of functions in the Data.Map interface I haven't had a chance to implement yet. For folding, the `foldMap`, `foldr`, and `foldl` functions are provided via the Data.Foldable interface. The Data.Traversable class is also implemented if you need to make changes to the trie along the way. These all give generic folding over the values stored in the trie. If you need access to the keys during folding you can use `foldrWithKey`, though it has to reconstruct the keys, which doesn't sound good for your use case. `toListBy` is a convenience wrapper around `foldrWithKey` which supports list fusion, so it has the same advantages and disadvantages compered to the Foldable/Traversable functions. If there's a particular function you still need, let me know and I can add an implementation for it. In terms of optimizing your code, one thing you'll surely want to do is to construct an intern table (Trie Int, IntMap ByteString) so that you only have to deal with Ints internally rather than ByteStrings. I haven't looked at your code yet to see how this would fit in, but it's almost always a requisite trick for handling large text corpora. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Terminology
Emmanuel Castro wrote: I am looking for the name of the property linking two functions f and g when : [f(a),f(b),f(c)] = g([a,b,c]) Is there a standard name? Generally these sorts of things are called homomorphisms. It's a terribly general term, but that's the one I've always seen to describe that pattern. It's also a bit like distributivity, though that probably doesn't highlight what you're interested in focusing on. -- Live well, ~wren ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Terminology
On Jun 15, 2010, at 1:42 PM, wren ng thornton wrote: Generally these sorts of things are called homomorphisms. It's a terribly general term, but that's the one I've always seen to describe that pattern. g is a list homomorphism, if you want to get specific. Equivalently, it is the list functor induced by f. (A functor is a morphism between categories. Lists form a category, and g is a morphism from lists to lists, since it is a homomorphism). I guess you can call the homomorphism characterization the list homomorphism induced by f ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Announce: hs2dot 0.1.1 - generate graphviz code by analyzing Haskell source code files
Hi, I've just released hs2dot on hackagedb. It's a small tool that lets you automatically generate graphviz/dot code that visualize the relations between data types, types and type classes. Example usage: hs2dot Hack.hs | dot -T pdf -o Hack.pdf Multiple files can be analyzed together as in hs2dot Foo.hs Bar.hs | dot -T png -o FooBar.png so their data types can point to each other. Example diagrams generated using h2dot can be found at http://github.com/finnsson/hs2graphviz/tree/master/Examples/ Examples of real code analyzed: http://github.com/finnsson/hs2graphviz/raw/master/Examples/Control.pdf (from hpage) http://github.com/finnsson/hs2graphviz/raw/master/Examples/Hack.png (from Hack) Example of mock code analyzed: http://github.com/finnsson/hs2graphviz/raw/master/Examples/TestCode.pdf (three files analyzed together) The tool is still far from complete. Better handling of algebraic data types and instance declarations are a must. GADTs, data families and type synonym families are not yet implemented so they wont turn up. -- Oscar ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
Wren -- thanks for the clarification! Someone said that Foldable on Trie may not be very efficient -- is that true? I use ByteString as a node type for the graph; these are Twitter user names. Surely it's useful to replace them with Int, which I'll try, but Clojure works with Java String fine and it simplifies all kinds of exploratory data mining and debugging to keep it as a String, so I'll try to get the most mileage from other things before interning. What's the exact relationship between Trie and Map and their respective performance? -- Alexy ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
deliverable: Wren -- thanks for the clarification! Someone said that Foldable on Trie may not be very efficient -- is that true? I use ByteString as a node type for the graph; these are Twitter user names. Surely it's useful to replace them with Int, which I'll try, but Clojure works with Java String fine and it simplifies all kinds of exploratory data mining and debugging to keep it as a String, so I'll try to get the most mileage from other things before interning. bytestring seems appropriate. What's the exact relationship between Trie and Map and their respective performance? Tries specialized to bytestring keys should outperform the generic Map. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Mining Twitter data in Haskell and Clojure
On Tuesday 15 June 2010 23:26:10, Don Stewart wrote:
deliverable:
Wren -- thanks for the clarification! Someone said that Foldable on
Trie may not be very efficient -- is that true?
I use ByteString as a node type for the graph; these are Twitter user
names. Surely it's useful to replace them with Int, which I'll try,
but Clojure works with Java String fine and it simplifies all kinds of
exploratory data mining and debugging to keep it as a String, so I'll
try to get the most mileage from other things before interning.
bytestring seems appropriate.
What's the exact relationship between Trie and Map and their
respective performance?
Tries specialized to bytestring keys should outperform the generic Map.
That would be desirable.
I've done some profiling with the sample data, and found that - if we
subtract the times for loading and saving the graphs - some 35-40% of the
time is spent looking up ByteStrings in Maps. That's far too much for my
liking. I'm not sure whether the lookup for e.g. an Int key would be much
faster, but I suspect it would be.
I've also fiddled a bit with the strictness and removed a bit of
unnecessary work, reduced the heap usage by ~20%, MUT times by ~15% and GC
times by ~50% (all for the tests on my box with a measly 1GB RAM).
It's still a far cry from a racehorse, but at least I can now run the
sample data for the entire 35 days without having my box thrashing madly :)
The result of my endeavours is attached.
Cheers,
Daniel
{-# LANGUAGE BangPatterns #-}
module SocRun (
UserStats,
DCaps,
SGraph(..),
SocRun(..), socRun, optSocRun
)
-- TODO exports
where
import Graph
import Data.Ord (comparing)
import Data.List (groupBy,sortBy,foldl1')
import Data.Foldable (foldl')
import Data.Function (on)
import qualified Data.Map as M
import Data.Map ((!))
import Data.List (maximum)
import System.IO
import Debug.Trace
import Data.Maybe
import Control.Monad ((=))
--import Data.Nthable -- generalized fst
--import Prelude hiding (fst,snd)
-- errln x =
-- hPrint stderr x
-- hFlush stderr
type DCaps = M.Map User (M.Map Day Float)
type TalkBalance = M.Map User Int
emptyTalk :: TalkBalance
emptyTalk = M.empty
data UserStats = UserStats {
socUS :: !Float,
dayUS :: !Int,
insUS :: TalkBalance,
outsUS :: TalkBalance,
totUS :: TalkBalance,
balUS :: TalkBalance}
newUserStats :: Float - Int - UserStats
newUserStats soc day = UserStats {socUS = soc, dayUS = day,
insUS = emptyTalk, outsUS = emptyTalk, totUS = emptyTalk, balUS = emptyTalk}
type UStats = M.Map User UserStats
data SocRun = SocRun {alphaSR :: !Float, betaSR :: !Float, gammaSR :: !Float,
socInitSR :: !Float, maxDaysSR :: Maybe Int}
optSocRun = SocRun 0.1 0.5 0.5 1.0 Nothing
data SGraph = SGraph {drepsSG :: !Graph, dmentsSG :: !Graph, dcapsSG :: !DCaps, ustatsSG :: !UStats}
paramSC (SocRun {alphaSR =a, betaSR =b, gammaSR =g}) = (a, b, g)
minMax1 (oldMin, oldMax) x =
let !newMin = oldMin `min` x
!newMax = oldMax `max` x in
(newMin, newMax)
minMax2 (oldMin, oldMax) (x,y) =
let !newMin = oldMin `min` x
!newMax = oldMax `max` y in
(newMin, newMax)
-- find the day range when each user exists in dreps
-- PRE: dreps must be sorted in adjacency lists by day!
-- (assert (reps-sorted1? dreps))
dayRanges :: Graph - M.Map User (Int, Int)
dayRanges dreps = M.map doDays dreps
where
doDays days = case fst $ M.findMin days of
!f - case fst $ M.findMax days of
!l - (f, l)
-- let (!start, _) = M.elemAt 0 days -- i.e. any map entry
-- range@(!f,!l) = foldl' minMax1 (start, start) (M.keys days) in
-- range
-- merge two day-ranges results
-- mergeDayRanges dr1 dr2 = M.unionWith min_max dr1 dr2
-- socRun :: Graph - Graph - SocRun - IO ()
socRun dreps dments opts =
let
params = paramSC opts
socInit = socInitSR opts
dcaps = M.empty -- TODO type
ustats = M.empty -- type
sgraph = SGraph dreps dments dcaps ustats
presMap = M.unionWith minMax2 (dayRanges dreps) (dayRanges dments)
!l0 = snd . snd $ M.findMax presMap
(!lastDay0, !dstarts) = foldl' updt (l0, M.empty) (M.assocs presMap)
updt (!ld, !m) (u,(f,l)) = (max ld l, M.insertWith' (++) f [u] m)
!firstDay = fst $ M.findMin dstarts
!lastDay = let x' = maybe lastDay0 (\y - min lastDay0 (firstDay + y - 1)) (maxDaysSR opts)
in
trace (doing days from ++ (show firstDay) ++ to ++ (show x'))
x'
tick sgraph day =
-- inject the users first appearing in this cycle
let
nus = newUserStats socInit day
!ustats= ustatsSG sgraph
newUsers = let x = dstarts ! day in
trace (adding ++ (show . length $ x) ++ new users on day ++ (show day))
x
!ustats' = foldl' insn
Re: [Haskell-cafe] Announce: hs2dot 0.1.1 - generate graphviz code by analyzing Haskell source code files
Oscar Finnsson oscar.finns...@gmail.com writes: Hi, I've just released hs2dot on hackagedb. It's a small tool that lets you automatically generate graphviz/dot code that visualize the relations between data types, types and type classes. This sounds very familiar to my SourceGraph package that's already on Hackage... You, however, also add the type signatures to your graph; I have the sneaking suspicion that this could get too noisy if you also try to visualise functions in a large module. The tool is still far from complete. Better handling of algebraic data types and instance declarations are a must. GADTs, data families and type synonym families are not yet implemented so they wont turn up. I, too, still haven't worked out how to deal with GADTs, etc. in my call graphs. -- 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] Haskell Indonesia
Max Cantor mxcan...@gmail.com writes: Its not indonesia, but the Singapore FP Users is pretty close by. [snip] Fine, if we're going to start promoting non-Indonesian Haskell groups/events, I give you AusHack: http://www.haskell.org/haskellwiki/AusHac2010 (It was about time for more promotion for this; it's starting in a months time!!!) -- 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
[Haskell-cafe] What is Haskell unsuitable for?
Hi all, Haskell is a great language and in a lot of ways it still hasn't found a niche, but that's part of what is great about it. But I wanted to ask people are more experienced with Haskell - what kinds of problems is it unsuited for? Have you ever regretted using it for something? Meaning if you could write the program over you would do it in another language. thanks ... -deech ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What is Haskell unsuitable for?
Hi Aditya Siram, - maybe shell scripting: running ghci takes longer than starting bash. Compiling is not always an option because executables are bigger than shell scripts or C executables Haskell could be the wrong choice if - an existing solution exists which does the job and you know you're not going to patch the source ( eg OpenOffice or Linux kernel, or simple build scripts. There is already make etc ) - want to run your app on targets which are not supported by Haskell or not supported too well. This includes Client scripting on browsers. I also think selling web apps which should run everywhere. If people read PHP they know how to install it. If they read Haskell I doubt. So if you want to sell apps to average mainstream custsomers Haskell can be a bad choice. - you want to collaborate with people who don't know the language I think you should go the other way round: Pick a task and ask which is the best tool to get the job done. But I think those items are obvious. Of course this is my point of view. Marc Weber ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: What is Haskell unsuitable for?
On Tue, 2010-06-15 at 19:47 -0400, aditya siram wrote: Hi all, Haskell is a great language and in a lot of ways it still hasn't found a niche, but that's part of what is great about it. But I wanted to ask people are more experienced with Haskell - what kinds of problems is it unsuited for? Have you ever regretted using it for something? Meaning if you could write the program over you would do it in another language. thanks ... -deech 1. Glueing a few highier level, object-oriented libraries if it is just glueing. 2. (Currently) AFAIK real-time applications although it is rather property of GHC GC then the language itself Regards signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What is Haskell unsuitable for?
* aditya siram aditya.si...@gmail.com [2010-06-15 19:47:37-0400] Hi all, Haskell is a great language and in a lot of ways it still hasn't found a niche, but that's part of what is great about it. But I wanted to ask people are more experienced with Haskell - what kinds of problems is it unsuited for? Have you ever regretted using it for something? Meaning if you could write the program over you would do it in another language. This topic was already discussed on this list, you might want to search the archives. -- Roman I. Cheplyaka :: http://ro-che.info/ Don't let school get in the way of your education. - Mark Twain ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] What is Haskell unsuitable for?
On 16 June 2010 15:45, Roman Cheplyaka r...@ro-che.info wrote: * aditya siram aditya.si...@gmail.com [2010-06-15 19:47:37-0400] Hi all, Haskell is a great language and in a lot of ways it still hasn't found a niche, but that's part of what is great about it. But I wanted to ask people are more experienced with Haskell - what kinds of problems is it unsuited for? Have you ever regretted using it for something? Meaning if you could write the program over you would do it in another language. This topic was already discussed on this list, you might want to search the archives. Spoilsport! :p Next you'll say there's no need for anyone to ask whether they prefer vi or emacs... ;-) -- 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
