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Search found 7019 results on 281 pages for 'learning clojure'.

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• erlang io:format, and a hanging web application

  - by williamstw

  While I'm learning a new language, I'll typically put lots of silly println's to see what values are where at specific times. It usually suffices because the languages typically have available a tostring equivalent. In trying that same approach with erlang, my webapp just "hangs" when there's a value attempted to be printed that's not a list. This happens when variable being printed is a tuple instead of a list. There's no error, exception, nothing... just doesn't respond. Now, I'm muddling through by being careful about what I'm writing out and as I learn more, things are getting better. But I wonder, is there a way to more reliably to [blindly] print a value to stdout? Thanks, --tim

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• How can I use the Spark library in my ActionScript project?

  - by bluenote

  I'm using Flare to develop a visualization. Being familiar to Java, Javascript and Eclipse it wasn't a big deal to familiarize myself to developing with Actionscript and Adobe FlashBuilder. I actually found that the learning curve is very flat. However, being new to Actionscript, I can't figure out how to use the Spark libraries that are part of Flex. I tried to add the libraries to the build path, with no success. I guess I'm confused about how Flash, Flex, Actionscript, Spark and Flare work together, even after reading the helpful answers on this question Does anybody know which part of the puzzle I'm missing? Thanks.

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• How can I do block-oriented disk I/O with Java? Or similar for a B+ tree

  - by Sanoj

  I would like to implement an B+ tree in Java and try to optimize it for disk based I/O. Is there an API for accessing individual disk blocks from Java? or is there an API that can do similar block-oriented access that fits my purpose? I would like to create something like Tokyo Cabinet in 100% Java. Is there anyone that knows what Java only databases like JavaDB is using in the back-end for this? I know that there are probably other languages than Java that can do this better, but I do this in a learning purpose only.

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• Getting started with html5 web sockets

  - by Stanni

  Hi, I'm very interested in learning about the new feature in html5 called web sockets. I've looked into it and have come out with a few questions. It seems that before I can start implementing this new technology into a web application of mine I need to have a web server which supports it. Does this involve downloading something and installing it on the said server? Is there more than one available? If so where do I find these? I already have experience with JavaScript and html/css of course, Are there any other languages I will need to learn to start using web sockets? Any additional information that you think I might need to know would be appreciated.

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• How Does Differential Execution Work?

  - by Brian

  I've seen a few mentions of this on SO, but staring at Wikipedia and at an MFC dynamic dialog demo did nothing to enlighten me. Can someone please explain this? Learning a fundamentally different concept sounds nice. Edit: I think I'm getting a better feel for it. I guess I just didn't look at the source code carefully enough the first time. I have mixed feelings about DE at this point. On the one hand, it can make certain tasks considerably easier. On the other hand, getting it up and running (i.e. setting it up in your language of choice) is not easy (I'm sure it would be if I understood it better)...though I guess the toolbox for it need only be made once, then expanded as necessary. I think in order to really understand it, I'll probably need to try implimenting it in another language.

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• Custom class object in Initialization list

  - by Michael

  I have a class Bar: class Bar { public: Bar(void); ~Bar(void); }; And a class Foo that gets a reference to Bar object as a constructor parameter and needs to save it in a private member bar_ : class Foo { private: Bar& bar_; public: Foo(Bar& bar) : bar_(bar) {} ~Foo(void) {} }; This doesn't compile : overloaded member function not found in 'Parser' missing type specifier - int assumed. Note: C++ does not support default-int Now i suspect couple of things that i need to assure, the second error is for Bar& bar_; declaration in Foo. Do i need to use an explicit constructor when declaring bar_ ? I am interested in learning how the compiler works regarding this matter, so a detailed explanation would be highly appreciated. Thanks.

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• Which langauge should i use for Artificail intelligence on web projects

  - by Mirage

  I have to do one project for my thesis involving Artificail intelligence , collaborative filtering and machine learning methods. I only know PHP/mysq/JS and there is not much AI stuff examples in PHP. There are some books on AI on internet but they use Java , Python. Now i have to apply AI techniques on web application. WHich language should i choose java or python. I searhed on internet that i can call java classes inside my php so that can help as as i am very good at php i have also seen that python can also be used with php as well So which way should i go and roughly how much it will take me to learn java i have done java basics but that was 6 years ago

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• int cannot be dereferenced

  - by Overlord

  Hello, I am beginning in java (I'm learning in microedition) and I got this error: "int cannot be dereferenced" in the following class: class DCanvas extends Canvas{ public DCanvas(){ } public void drawString(String str, int x, int y, int r, int g, int b){ g.setColor(r, g, b); //The error is here g.drawString(str, x, y, 0); //and here } public void paint(Graphics g){ g.setColor(100, 100, 220); g.fillRect(0, 0, getWidth(), getHeight()); } } What am I doing wrong here? Well I came from PHP and ECMAScripts where I was able to pass my function arguments this way so I really don't understand this error.

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• For simple C cmd programs: how to add "program executed in 12,345 seconds" ?

  - by WoodsieLord

  I'm a windows user, and I'm learning C. I use Codeblocks and visual c++ 2008 express at home to write simple C command line programs (I'm a beginner) and I find really useful when codeblocks adds a few lines at the end with the time it takes (example: "Process returned 0 (0x0) execution time : 6.848 s"). I want to add this functionality to the .exe so I can 'benchmark' or 'test' the program on a few computers. I tried using time(NULL) but it only works with 1 second precision. I also found very interesting answers here (I'm actually looking for the same thing): http://stackoverflow.com/questions/2173323/calculating-time-by-the-c-code The solution proposed by Mark Wilkins, works fine on visual c++ 2008 express on my windows 64 bit PC, but the .exe does not work anywhere else. Am I doing something wrong? I would like a method to count elapsed wall time for my programs, that must have 32bit compatibility. Thanks in advance!

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• What are some good ways to promote my Android application?

  - by Bryan Denny

  I'm a new Android developer and I just released a free, open source tipping calculator app called Tippy Tipper. I created this app to get myself familiar with Android and to hopefully provide a good example app for other new developers to look at. Now that I've overcome the challenges of learning how to program, test and release my Android app, I've come across a new challenge: marketing! What are some good ways to promote my app to the Android community? Can anyone with some experience talk about how they did this successfully with their own app?

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• Storage for large gridded datasets

  - by nullglob

  I am looking for a good storage format for large, gridded datasets. The application is meteorology, and we would prefer a format that is common within this field (to help exchange data with others). I don't need to deal with special data structures, and there should be a Fortran API. I am currently considering HDF5, GRIB2 and NetCDF4. How do these formats compare in terms of data compression? What are their main limitations? How steep is the learning curve? Are there any other storage formats worth investigating? I have not found a great deal of material outlining the differences and pros/cons of these formats (there is one relevant SO thread, and a presentation comparing GRIB and NetCDF).

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• How to persist non-trivial fields in Play Framework

  - by AlexR

  I am trying to persist complex objects using Ebeans in Play Framework (2.03). In particular, I've created a class that contains a field of type weka.classifier.Classifier (Weka is a popular machine learning library - see http://weka.sourceforge.net/doc/weka/classifiers/Classifier.html). Classifier implements Serializeable so I hoped that I can get away with something like @Entity @Table(name = "classifiers") public class ClassifierData extends Model { @Id public Long id; public Classifier classifier; } However, the Evolutions script suggests the following database structure: create table classifiers ( id bigint auto_increment not null, constraint pk_classifiers primary key (id)) ) In other words, it ignores the field of type Classifier. (The database is MySQL if it makes any difference) What should I do to store complex serializeable objects using Ebean/Evolutions/PlayFramework?

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• C# Script version of PyBinding for WPF

  - by Jim Strav

  I wrote a CSharpScriptBinding roughly equivalent to the PyBinding on CodePlex. It uses the C# script engine from http://www.csscript.net. After I wrote it, I kind of decided it might not really be something good to use. Although it caches the compiled script code as an already compiled Assembly, my concern is that I will have one temporary Assembly created each time I use the binding. Will this add up to a problem in the future? If so, maybe there is a way in the C# script engine that I don't know about to optimize this further...? Any thoughts to confirm my suspicion that this was just a bad idea (but useful excersise in learning more about bindings and converters)?

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• MongoDB: embedding performance question

  - by Alex

  I just started learning MongoDB, and I really like the idea of embedding collections instead of referencing them. MongoDB's documentation recommends to use embedding if performance is needed. I just thought about a simple forum model. Let's say, every board category has several boards, every board has several topics, and every topic has several messages. All of these collections are embedded. After some time the size of the board category will be huge. Way more than the 2MB limit. Does this mean that there's a flaw in this design?

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• Where to start openGL ES to create and rotate a cube in an iPhone?

  - by micropsari

  Hello. I've done some apps on iPhone using Objevtive-C and Cocos2d, and I'd like to start learning 3D. My first goal is to make a very simple app that: - Displays a 3D cube in the center of the screen. - And move the camera around the cube I want something very simple: no texture, no background. Where should I start to be able to do this app? I'm searching for some tutorials or exemples. Thanks!

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• Store interface in array list java

  - by agazerboy

  Hi all, I am learning java. I am trying to use composite design pattern. I am trying to use following logic. ( Don't laugh I know it is very basic :) ) Item -> interface Folder -> class File -> class In folder class, can I create an arraylist of Item to store files information? ArrayList<Item> info = ArrayList<Item>(); Or should I use Folder Arraylist? ArrayList<Folder> info = ArrayList<Folder>(); I don't know if interface can store real data as there is no variable just function definitions. Thanks for helping a newbie :)

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• Html POST and return the same form with the values

  - by vtortola

  Hi, I'm learning web development, and I don't know how do this simple thing. I've a html form with "text", "radio" and "checkbox" controls, that POST the values to the server and it saves them, for example in a file. I save the POST in raw format: key=value&key=value&key=value&key=value and I'd like that when the user open the form back, return the form with the saved values already in the controls. Is there any neat way to do this? Or should I parse the POST string and set the values one by one in the controls at the server level? I think, I could return the saved data in a hidden input control, and after with a javascript I could do a getElementById(key) and set the value to each input control... but do I need to put the post string in a special format? How would you do it? Thank you in advance.

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• How do I check the input data type of a variable in C++?

  - by atinesh singh

  i'm atinesh currently started learning c++ but i've one doubt about how to check the data type of input variable in c++. #include<iostream.h> void main() { double a,b; cout<<"Enter two double values"; cin>>a>>b; if() //if condition false then cout<<"data entered is not of double type"; //i'm having trouble for identifying whether data //is double or not how to check please help me }

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• Write a network simulator for fun

  - by Jono

  I want to write my own network simulator, for fun and for personal challenge. I hope to learn both new programming techniques, and a little bit more about networking. Previous object-oriented attempts ended very quickly, but I've recently downloaded and played with Microsoft's Axum (a new version was released today) and their Concurrency and Co-ordination Runtime. As I come from a very OO dominant background, I had never heard of Actor-oriented programming before; now it seems I've had my head in the sand until Scala and F# brought the paradigm to me. My questions are: a) is actor-oriented programming a better choice than object-oriented programming for this task, and if so b) where is a good place to start learning actor-oriented design?

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• ASP.NET C# Writting a string into html to validate ?

  - by Yardstermister

  I am pretty new to ASP.NET and C# I have spent the day learning the basics of the ASP.NET Membership provider I have built all my validator but are getting stuck at outputting my error message on the page. private void LogCreateUserError(MembershipCreateStatus status, string username) { string reasonText = status.ToString(); switch (status) { case MembershipCreateStatus.DuplicateEmail: case MembershipCreateStatus.DuplicateProviderUserKey: case MembershipCreateStatus.DuplicateUserName: reasonText = "The user details you entered are already registered."; break; case MembershipCreateStatus.InvalidAnswer: case MembershipCreateStatus.InvalidEmail: case MembershipCreateStatus.InvalidProviderUserKey: case MembershipCreateStatus.InvalidQuestion: case MembershipCreateStatus.InvalidUserName: case MembershipCreateStatus.InvalidPassword: reasonText = string.Format("The {0} provided was invalid.", status.ToString().Substring(7)); break; default: reasonText = "Due to an unknown problem, we were not able to register you at this time"; break; } //CODE TO WRITE reasonText TO THE HTML PAGE ?? } What is the best way to output the varible result onto the page as I have relied upon the built in ASP:Validators untill now.

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• Method of getting text on a windows form ( unmanaged C++ project )

  - by Donovan

  I'm in the process of learning C++. I've created a boilerplate Win32 app within VC++ 2008. I've studied through the code and am ready do do a bit of experimenting. I thought it would be cool to print all the windows messages received in the message loop to the form created via the boilerplate code. I for the life of me, can't figure out the method of getting text onto that form. I can't seem to identify and named object that I can use to reference that damn form. The best I can figure is I need to use the handle to reference the form somehow. Still, even if I did know how to reference the form, I'm not sure I know how I would create a label to display the text. Anyway, if someone could just point out what methodology I need to learn to make this happen it would be much appreciated. Thanks, Donovan

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• Book resources for x86/x64 assembly programming on Win platform

  - by Scott Davies

  Hello, I ran a search for assembly language resources on stackoverflow.com and found some interesting results, but they seemed to boil down to two groups: 1) Assembly references to old ia32 architecture, such as the 80386 to Pentium 2) Windows agnostic books. Most of the commenters make the point that assembler is CPU dependent and that the OS is irrelevant, but it seems pointless to me to pick a book that has assembly examples that refer to MS-DOS interrupts and memory layouts. Likewise, learning assembler on Linux would seem to produce Linux executables Are there any: 1) Modern 2) x86/x64 3) on Windows platform - book resources available ? The reason I am targeting the Win platform is I would like to do low-level, OS internals programming, to supplement my Win C/C++ work. Thanks

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• ActionController::RoutingError

  - by Steve

  Hi All, I am just learning Rails. I had encountered a routing error, though I think I have specified the correct rules in the routing.rb. I have attached the code. Please help routing.rb map.connect ':controller/:action' map.connect ':controller/:action/:id' map.connect ':controller/:action/:id.:format' Controller class EntriesController < ApplicationController def sign_in @name = params[:visitor_name] end end View <html> <head><title>Hello <%=h @name %></title></head> <body> <%=h @name %> <% form_tag :action => 'sign_in' do %> <p>Enter your name: <%= text_field_tag 'visitor_name', @name %></p> <%= submit_tag 'Sign in' %> <% end %> </body> </html> Thanks

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• Working with QWords

  - by Glenn1234

  I'm learning and in the course of that working on an assembler conversion which uses QWORDs a lot (x86-32bit). Now my reference material doesn't have anything on working with such values beyond the obvious of splitting them up into the 32-bit registers. I guess they're on the old side. The newer processors have mmx and sse instructions and the like. Would I be served well to look into those instructions for solving this? What is the best way to handle doing work on QWORD values?

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• Help using Lisp debugger

  - by Joel

  I'm trying understand how to interpret the output of, and use, the Lisp debugger. I've got a pretty simple Backtrace for the evaluation of my function, but I cann't seem to work out how to use it to find out in which Lisp 'form' in my function the exception occurred. I'd appreciate any clues as to what I should be doing, to find the source of the error. I've attached a screen shot (if it's too small to read I can re-post it in parts), with the debug output, the function and the repl (please ignore my very wrong function, I'm just interested in learning how to use the debugger properly). In addition, I hit 'v' on the first frame to go to the source, but this resulted in the error at the bottom of the screen.

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