Search Results

Search found 18249 results on 730 pages for 'real world haskell'.

Page 17/730 | < Previous Page | 13 14 15 16 17 18 19 20 21 22 23 24  | Next Page >

  • Real time SQL database updates between multiple VB.NET clients

    - by Marcel
    Hi, I hope somebody can help me out on this question. I'm using a SQL database and I'm writing a VB.NET client application. This application is used on multiple computers at the same time. If one of the clients makes an update to the database I would like to have the other clients to be aware of the update. Has ony one already done this before? Thank you very much! Marcel

    Read the article

  • real time updates for new page events

    - by Ben Ford
    I know there's a few questions knocking around on this topic but none quite the same. I'm currently searching by location for all the pages relating to a particular geographic location and caching their events in a database. The problem being I have to currently loop through all the pages i'm watching frequently to check for updates. At the moment the 10,000 Pages I'm keeping track of takes a good while to update. It would be much neater (and nicer to fb) to be notified instead of polling. Does anyone know of a more efficient to do this? Thanks Ben

    Read the article

  • Android "Hello World" Problem...

    - by Biranchi
    Hi, this is the code i have written package com.android.helloandroid; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; public class HelloAndroid extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); TextView tv = new TextView(this); tv.setText("Hello, Android"); setContentView(tv); } } And i am getting these errors [2010-04-06 19:24:03 - Emulator] 2010-04-07 00:49:03.366 emulator[498:903] Warning once: This application, or a library it uses, is using NSQuickDrawView, which has been deprecated. Apps should cease use of QuickDraw and move to Quartz. [2010-04-06 19:34:42 - TestApp] emulator-5554 disconnected! Cancelling 'com.test.AndroidApp.TestAppActivity activity launch'! I have the latest sdk and ADT installed. What is the solution ???? Thanks

    Read the article

  • Real-Time Data Streaming to Multiple Clients

    - by AriX
    Hi all, I would like to write an application which will stream data at 2400 baud over the internet from a server to multiple clients. The data will be the same for each client, and it would probably be fine to send it as a UDP stream, since exact data accuracy is not a 100% necessity, as there are checksums built-in to the data format and the data will be sent repeatedly on a loop. What is the best way to do this? I would want to write the server in C, but I don't know how to best multicast this data to the different clients that would be receiving it all over the country. I'm sure this seems like a pretty draconian way to go about my project, as opposed to just using some sort of fetch command, but I'd prefer to do it this way if possible.

    Read the article

  • How do you do real time document tracking?

    - by Nimish
    I was considering diff Document Tracking options and came across DocTracking.com. DocTracking.com allows you to upload documents (PDF Word etc) and adds some kind of invisible tracking to it and returns the document to you which can then be used just like you would use the document otherwise. This tracking tells you when your documents were opened, who opened them (IP), geo-location of opening if they are re-opened or forwarded, what pages were read and how long it was read for, what was printed. Any leads on how this could be done would be appreciated.

    Read the article

  • How do I code a tree of objects in Haskell with pointers to parent and children?

    - by axilmar
    I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

    Read the article

  • Misconceptions about purely functional languages?

    - by Giorgio
    I often encounter the following statements / arguments: Pure functional programming languages do not allow side effects (and are therefore of little use in practice because any useful program does have side effects, e.g. when it interacts with the external world). Pure functional programming languages do not allow to write a program that maintains state (which makes programming very awkward because in many application you do need state). I am not an expert in functional languages but here is what I have understood about these topics until now. Regarding point 1, you can interact with the environment in purely functional languages but you have to explicitly mark the code (functions) that introduces them (e.g. in Haskell by means of monadic types). Also, AFAIK computing by side effects (destructively updating data) should also be possible (using monadic types?) but is not the preferred way of working. Regarding point 2, AFAIK you can represent state by threading values through several computation steps (in Haskell, again, using monadic types) but I have no practical experience doing this and my understanding is rather vague. So, are the two statements above correct in any sense or are they just misconceptions about purely functional languages? If they are misconceptions, how did they come about? Could you write a (possibly small) code snippet illustrating the Haskell idiomatic way to (1) implement side effects and (2) implement a computation with state?

    Read the article

  • What's the proper term for a function inverse to a constructor? Deconstructor, destructor, or something else?

    - by Petr Pudlák
    Edit: I'm rephrasing the question a bit. Apparently I caused some confusion because I didn't realize that the term destructor is used in OOP for something quite different - it's a function invoked when an object is being destroyed. In functional programming we (try to) avoid mutable state so there is no such equivalent to it. (I added the proper tag to the question.) Instead, I've seen that the record field for unwrapping a value (especially for single-valued data types such as newtypes) is sometimes called destructor or perhaps deconstructor. For example, let's have (in Haskell): newtype Wrap = Wrap { unwrap :: Int } Here Wrap is the constructor and unwrap is what? I've seen both, for example: ... Most often, one supplies smart constructors and destructors for these to ease working with them. ... at Haskell wiki, or ... The general theme here is to fuse constructor - deconstructor pairs like ... at Haskell wikibook (here it's probably meant in a bit more general sense). The questions are: How do we call unwrap in functional programming? Deconstructor? Destructor? Or by some other term? And to clarify, is this terminology applicable to other functional languages, or is it used just in the Has

    Read the article

  • Subscribable World Cup 2010 Calendar

    - by jamiet
    I bang on quite a lot on this blog about ways in which data can get published over the web and one of the most interesting ways, in my opinion, of publishing data in a structured manner that is well understood is to use the iCalendar specification. There isn’t much information in the world that doesn’t have some concept of “when” so iCalendar is a great way of distributing that information. You have probably used iCalendar at some point without even knowing about it. All files with a .ics suffix are iCalendar format files and that is why you can happily import them into Outlook, Hotmail Calendar, Google Calendar etc… where they can be parsed and have the semantic data (when, where and who) extracted from them. Importing of iCalendar format data is really only half the trick though; in my opinion the real value of iCalendar-formatted calendar is the ability to subscribe to them. Subscribing has a simple benefit over importing but that single benefit is of massive importance: a subscriber to an iCalendar calendar can periodically check to see if any updates have been made and, if they have, automatically update the local copy. The real benefit to the user is the productivity gain – a single update to an iCalendar means that all subscribers are automatically made aware of the change and there is zero effort on the part of the subscriber; as my former colleague Howard van Rooijen is fond of saying, “work smarter not harder” – nowhere is this edict more ably demonstrated than subscribing versus importing of calendars. If you want to read some more thoughts about iCalendar then go and read my past blog post Calendar syndication - My big hope for 2009's breakthrough technology or better still go and seek out Jon Udell who speaks very authoritatively on the issue of iCalendar. With this subject of iCalendar on my mind I was interested to discover (via Steve Clayton’s blog post Download the world cup fixtures) that the BBC had made a .ics file available containing all of the matches in the upcoming World Cup. As you can probably guess this was a file that was made available so that it could be imported into your calendar of choice. It had one obvious downside though, right now nobody knows who is going to be playing in the knock-out stages so the calendar looks like this: with no teams being named after 25th June. How much more useful would this calendar have been if the BBC had made it possible to subscribe to the calendar instead, thus the calendar could be updated with the teams for the knock out stages when they are known and every subscriber would have a permanently up-to-date record of all the fixtures in their calendar. Better still, the calendar could be updated with match results as well or perhaps even post a match report from the BBC sport pages; when calendars are made subscribable a sea of opportunity opens up for distribution of information. So with that in mind I have decided to go one better than the BBC. I have imported their .ics into a brand new Hotmail calendar and made it publicly available at the following URLs: HTML http://cid-dc1ed121af0476be.calendar.live.com/calendar/World+Cup+2010/index.html iCalendar webcal://cid-dc1ed121af0476be.calendar.live.com/calendar/World+Cup+2010/calendar.ics The link you’re really interested in is the second one - click on that and it should open up in your calendar software of choice. Or, if you want to view it in an online calendar such as Hotmail Calendar or Google Calendar, copy and paste that URL into the appropriate place. Some people have told me they’re having trouble with the iCalendar link in which case hit the HTML link and then click “View ICS” at the resultant web page: I shall endeavour to keep the calendar updated throughout the World Cup and even if I don’t you’re no worse off than if you had imported the BBC’s .ics file so why not give it a try? If I do keep it up to date then you will have a permanent record of the 2010 World Cup available in your calendar. Forever. If you have your calendar synced to your smartphone then you’ll be carrying match reports around with you without you having to do a single thing. Surely that’s worth a quick click isn’t it?   If you have any thoughts let me have them in the comments below. Thanks for reading. @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

    Read the article

  • F# vs Haskell vs Lisp - which language to learn?

    - by empi
    I've heard a lot about functional programming languages and I'm willing to learn one. I guess it will be mostly for fun, however, I hope it will improve my programming skills. I have mostly C#/.NET background, so my first choice is to learn F# (because of .NET and familiarity with Visual Studio). On the on other hand, I wonder if F# has features like Lisp macros or Haskell higher order functions. Could you compare F#, Haskell and Lisp? Which one will be the language of your choice?

    Read the article

  • Finding the shortest path between two points on a grid, using Haskell.

    - by esperantist
    This is a problem that I can easily enough solve in a non-functional manner. But solving it in Haskell is giving me big problems. Me being inexperienced when it comes to functional programming is surely a reason. The problem: I have a 2D field divided into rectangles of equal size. A simple grid. Some rectangles are empty space (and can be passed through) while others are impassable. Given a starting rectangle A and a destination rectangle B, how would I calculate the shortest path between the two? Movement is possible only vertically and horizontally, in steps a single rectangle large. How would I go about accomplishing this in Haskell? Code snippets certainly welcome, but also certainly not neccessary. And links to further resources also very welcome! Thanks!

    Read the article

  • Are there tools that would be suitable for maintaining a changelog for a Cabal Haskell package?

    - by Norman Ramsey
    I'm working fast and furiously on a new Haskell package for compiler writers. I'm going through many minor version numbers daily, and the Haskell packaging system, Cabal, doesn't seem to offer any tools for updating version numbers or for maintaining a change log. (Logs are going into git but that's not visible to anyone using the package.) I would kill for something equivalent to Debian's uupdate or dch/debchange tools. Does anyone know of general-purpose tools that could be used to increment version numbers automatically and add an entry to a change log?

    Read the article

  • EE Major : Should I learn Ruby on Rails or Haskell?

    - by Vivek
    Hi,I've just completed my freshman year in college and am majoring in EE (with a lot of interest in CS as well) . I know some Python,C/C++ and Java and also a little bit of Actionscript . I am planning to learn either Haskell or Ruby on Rails. Haskell because it is a functional programming language, and I've been really impressed by this paradigm and Ruby on Rails , as I don't know any 'web' programming language and have heard that you can develop apps in RoR very easily and quickly . Which one should I learn ? and please suggest some links / books for starting off .

    Read the article

  • How do Scala parser combinators compare to Haskell's Parsec?

    - by artif
    I have read that Haskell parser combinators (in Parsec) can parse context sensitive grammars. Is this also true for Scala parser combinators? If so, is this what the "into" (aka "") function is for? What are some strengths/weaknesses of Scala's implementation of parser combinators, vs Haskell's? Do they accept the same class of grammars? Is it easier to generate error messages or do other miscellaneous useful things with one or the other? How does packrat parsing (introduced in Scala 2.8) fit into this picture? Is there a webpage or some other resource that shows how different operators/functions/DSL-sugar from one language's implementation maps onto the other's?

    Read the article

  • How do I get the sums of the digits of a large number in Haskell?

    - by Tim
    I'm a C++ Programmer trying to teach myself Haskell and it's proving to be challenging grasping the basics of using functions as a type of loop. I have a large number, 50!, and I need to add the sum of its digits. It's a relatively easy loop in C++ but I want to learn how to do it in Haskell. I've read some introductory guides and am able to get 50! with sum50fac.hs:: fac 0 = 1 fac n = n * fac n - 1 x = fac 50 main = print x Unfortunately at this point I'm not entirely sure how to approach the problem. Is it possible to write a function that adds (mod) x 10 to a value and then calls the same function again on x / 10 until x / 10 is less than 10? If that's not possible how should I approach this problem? Thanks!

    Read the article

  • Right rotate of tree in Haskell: how is it work?

    - by Roman
    I don't know haskell syntax, but I know some FP concepts (like algebraic data types, pattern matching, higher-order functions ect). Can someone explain please, what does this code mean: data Tree ? = Leaf ? | Fork ? (Tree ?) (Tree ?) rotateR tree = case tree of Fork q (Fork p a b) c -> Fork p a (Fork q b c) As I understand, first line is something like Tree-type declaration (but I don't understand it exactly). Second line includes pattern matching (I don't understand as well why do we need to use pattern matching here). And third line does something absolutely unreadable for non-haskell developer. I've found definition of Fork as fork (f,g) x = (f x, g x) but I can't move further anymore.

    Read the article

  • Pass Types as arguments to a function in Haskell?

    - by Charles Peng
    The following two functions are extremely similar. They read from a [String] n elements, either [Int] or [Float]. How can I factor the common code out? I don't know of any mechanism in Haskell that supports passing types as arguments. readInts n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Int readFloats n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Float I am at a beginner level of Haskell, so any comments on my code are welcome.

    Read the article

  • How do you get 100% code coverage with guards in Haskell?

    - by dan_waterworth
    I'm trying to get (and prove) 100% test coverage for some code I'm writing in Haskell using HPC. However if I write something like this: fac n | n > 0 = n * (fac (n - 1)) | otherwise = 1 Then the second expression of the guard statement has always True tagged to it. What is the easiest way to overcome this in the general case? edit: Just to clarify. This code: fac n = if n > 0 then n * (fac (n - 1)) else 1 Works fine with HPC, (running it gives 100% code coverage). I'm basically suffering from this problem: http://hackage.haskell.org/trac/ghc/ticket/3175

    Read the article

  • Is an Ethernet point to point connection without a switch real time capable?

    - by funksoulbrother
    In automation and control, it is commonly stated that ethernet can't be used as a bus because it is not real time capable due to packet collisions. If important control packets collide, they often can't keep the hard real time conditions needed for control. But what if I have a single point to point connection with Ethernet, no switch in between? To be more precise, I have an FPGA board with a giga-Ethernet port that is connected directly to my control PC. I think the benefits of giga Ethernet over CAN or USB for a p2p connection are huge, especially for high sampling rates and lots of data generation on the FPGA board. Am I correct that with a point to point connection there can't be any packet collisions and therefore a real time environment is given even with ethernet? Thanks in advance! ~fsb

    Read the article

  • Consuming Hello World pagelet in WebCenter Spaces

    - by astemkov
    Introduction The goal of this exercise is to show you how can you use Hello World pagelet that you just created from your web space. Assumptions Let's assume the following: Pagelet Producer is running on http://pageletserver.company.com:8889/pagelets/ WebCenter is running on http://webcenter.company.com:8888/webcenter/ You created Hello_World pagelet as described here. For our exercise we will need a space created. So let's login into WebCenter Portal and create a space called "myspace" using "Portal Site" template: Registering Pagelet Producer with WebCenter portal In order to use our newly created pagelet from WebCenter Spaces, we first need to register Pagelet Producer: Click "Administraion" link on WebCenter toolbar Open the "Configuration" tab Click on "Services" link on the upper-left corner of the page Click on "Portlet Producers" link on the right hand pane of the screen Click on "Register" button Select "Pagelet Producer" radio button and type Producer Name = "MyPageletProducer" Server URL = http://pageletserver.company.com:8889/pagelets/ Click "Test" button If everything is succesful you will see the following screen: Now click "OK'. Pagelet producer is registered: Inserting Hello World pagelet to WebCenter Space Now let's insert Hello World pagelet into "myspace" page: Let's go back to "myspace", click on the icon in a upper-right corner of the page and select "Edit Page" Click on one of the "Add Content" buttons: Select "Mash-Ups": Select "Pagelet Producers: You will see the MyPageletProducer that we just registered: Click on it. You will see the library "MyLib" that contains our "Hello_World" pagelet. Click on "MyLib" and you will see "Hello_World" pagelet. Click on "Add" button, and then "Close" button. Click "Save" button, and then "Close". Now we see that our "Hello World" pagelet is inserted into "myspace" page:

    Read the article

  • Real life example of an agile game development process outputs

    - by Ken
    I'm trying to learn about applying agile methodologies to game development. But seems to be impossible to find real life examples. There seems to be plenty of material discussing how 'in principle' agile is applied to a game. But that is NOT what I am looking for. I have the Keith book. What I AMlooking for are real EXAMPLES of things like; Initial user stories Final user stories (complete, covering the entire game requirements) Acceptance criteria Task list Sprint backlogs (before and after each sprint) The agile books seem to have some limited examples, many of which seem contrived or limited. In this era of open source software, there must be a publicly available documented example of the process applied to a real game. I am asking specifically about games because they are so different from normal applications. Regular applications are built to all users to complete specific tasks in order to get stuff done(book a room, print a report etc). People play games for much less tangible reasons, so I think the process is significantly different. [it doesn't have to be scrum, it could be any process, just needs to be a real life example game and be reasonably complete]

    Read the article

  • Real-time stock market application

    - by Sam
    I'm an amateur programmer. I'd like to develop a software application (like Tradestation), to analyse real-time market data. Please teach me if the following approach is correct, ie the procedures, knowledge or software needed etc: Use a DB to read the real-time feed from data provider: what should be the right DB to use? I know it should be a time serious one. Can I use SQL, Mysql, or others? What database can receive real-time data feed? Do I need to configure the DB to do this? If the real-time data is in ASCII form, how can it be converted to those that can be read by the DB and my application? Should I have to write codes or just use some add-ins? What kind of add-in are needed? How should I code the program to retrieve the changing data from the DB so that the analysis software screen data can also change asynchronously? (like the RTD in excel) Which aspects of programming do I need to learn to develop the above? Are there web resources/ books I can refer to for more information?

    Read the article

  • Flickering problem with world matrix

    - by gnomgrol
    I do have a pretty wierd problem today. As soon as I try to change my translation- or rotationmatrix for an object to something else than (0,0,0), the object starts to flicker (scaling works fine). It rapid and randomly switches between the spot it should be in and a crippled something. I first thought that the problem would be z-fighting, but now Im pretty sure it isn't. I have now clue at all what it could be, here are two screenshots of the two states the plant is switching between. I already used PIX, but could find anything of use (Im not a very good debugger anyway) I would appreciate any help, thanks a lot! Important code: D3DXMatrixIdentity(&World); D3DXVECTOR3 rotaxisX = D3DXVECTOR3(1.0f, 0.0f, 0.0f); D3DXVECTOR3 rotaxisY = D3DXVECTOR3(0.0f, 1.0f, 0.0f); D3DXVECTOR3 rotaxisZ = D3DXVECTOR3(0.0f, 0.0f, 1.0f); D3DXMATRIX temprot1, temprot2, temprot3; D3DXMatrixRotationAxis(&temprot1, &rotaxisX, 0); D3DXMatrixRotationAxis(&temprot2, &rotaxisY, 0); D3DXMatrixRotationAxis(&temprot3, &rotaxisZ, 0); Rotation = temprot1 *temprot2 * temprot3; D3DXMatrixTranslation(&Translation, 0.0f, 10.0f, 0.0f); D3DXMatrixScaling(&Scale, 0.02f, 0.02f, 0.02f); //Set objs world space using the transformations World = Translation * Rotation * Scale; shader: cbuffer cbPerObject { matrix worldMatrix; matrix viewMatrix; matrix projectionMatrix; }; // Change the position vector to be 4 units for proper matrix calculations. input.position.w = 1.0f; // Calculate the position of the vertex against the world, view, and projection matrices. output.position = mul(input.position, worldMatrix); output.position = mul(output.position, viewMatrix); output.position = mul(output.position, projectionMatrix);

    Read the article

  • Facebook Payments & Credits vs. Real-World & Charities

    - by Adam Tannon
    I am having a difficult time understanding Facebook's internal "e-commerce microcosm" and what it allows Facebook App developers to do (and what it restricts them from doing). Two use cases: I'm an e-com retailer selling clothes and coffee mugs (real-world goods) on my website; I want to write a Facebook App that allows Facebook users to buy my real-world goods from inside of Facebook using real money ($ USD) I'm highschool student trying to raise money for my senior class trip and want to build a Facebook App that allows Facebook users to donate to our class using real money ($ USD) Are these two scenarios possible? If not, why (what Facebook policies prohibit me from doing so)? If so, what APIs do I use: Payments or Credits? And how (specifically) would it work? Do Facebook Users have to first buy "credits" (which are mapped to $ USD values under the hood) and pay/donate with credits, or can they whip out their credit card and pay/donate right through my Facebook App? I think that last question really summarizes my confusion: can Facebook users enter their credit card info directly into Facebook Apps, or do you have to go through Payments/Credits APIs as a "middleman"?

    Read the article

< Previous Page | 13 14 15 16 17 18 19 20 21 22 23 24  | Next Page >