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  • Emacs align-regexp on = but not ==

    - by Karl
    I am working in Haskell and frequently come across code similar to the following: func i j | i == j = i | otherwise = j I want to align on the '=' character using align-regexp but don't have the elisp knowhow. I have tried just doing " = " without the quotes, but this inserts an unwanted space character before each '='. I have found a proposed solution here but I can't seem to get that to do anything at all. Please help me write a function or hard-coded macro that will allow me to set a keybinding for this.

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  • How can I compile a GUI executable with ghc?

    - by martingw
    I ported a little Haskell program I wrote from Mac to Windows. It's a GUI application (wxHaskell, compiled with ghc 6.12.1), so it does not need the command prompt window to open. It does so, anyway, so my question: What must I do so that the program starts without opening a prompt window first? Is there some ghc switch for this?

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  • Higher-kinded Types with C++

    - by Venkat Shiva
    This question is for the people who know both Haskell (or any other functional language that supports Higher-kinded Types) and C++... Is it possible to model higher kinded types using C++ templates? If yes, then how?

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  • Is there a suitable replacement for C++, when I would like to write video processing applications?

    - by Nisanio
    Hi I want to write a video editing software, and the "logical" conclusion is that the language I must to use is C++... But I don't like it (sorry c++ fans) I would like to write it with something cool, like Lisp or Haskell or Erlang... But I don't know if the open source implementation of those languages (I don't have money to buy licenses) let me made a competitive software (in the performance area) What do you think? what do you recommend?

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  • Scala Hoogle equivalent?

    - by Alexey Romanov
    Hoogle allows you to search many standard Haskell libraries by either function name, or by approximate type signature. I find it very useful. Is there anything like Hoogle for Scala? Search in ScalaDoc 2 only finds types and packages by name.

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  • How to install new modes in emacs 23 on OS X?

    - by estanford
    I just downloaded the Haskell and J modes off of SourceForge, and I'm having trouble figuring out how to make them interface with emacs 23. Google searches yield detailed instructions for emacs 22, but it looks like changes have been made that make it hard to figure out where I'm supposed to stick the binaries. The internal documentation seems to assume more experience with emacs internals than I currently have, and the problem has resisted solution for several days. Does anyone know how to get these modes up and running?

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  • Outputing UTF-8 string on Mac OS's Terminal

    - by SuperBloup
    I got a programm in haskell outputting utf-8 using the package utf8-string and using only the output functions of this package. I set the encoding of each file I write to this way : hSetEncoding myFile utf8 {- myFile may be stdout -} but when I try to output : alpha = [fromEnum 0x03B1] {- a -} instead of the nice alpha letter I got on Linux (or in a file on windows), I got the following : α The weird thing is even if I try to write the output on a file, I can't read it back with mvim as an utf-8 file. Is there any way to get the correct behaviour

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  • Where are the clever uses of strict evaluation?

    - by devonrt
    It seems like there are plenty of examples of clever things being done in a lazily-evaluated language that can't be done in an environment with strict evaluation. For example infinite lists in Haskell or replacing every element in a tree with the tree's minimum value in one pass. Are there any examples of clever things being done in a strictly-evaluated language that can't easily be done in a lazily-evaluated language?

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  • What is wrong with this list comprehension code?

    - by suresh
    My aim is to list all elements of the array a whose values are greater than their index positions. I wrote a Haskell code like this. [a|i<-[0..2],a<-[1..3],a!!i>i] When tested on ghci prelude prompt, I get the following error message which I am unable to understand. No instance for (Num [a]) arising from the literal 3 at <interactive>:1:20 Possible fix: add an instance declaration for (Num [a])

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  • Newbie: understanding main and IO()

    - by user1640285
    While learning Haskell I am wondering when an IO action will be performed. In several places I found descriptions like this: "What’s special about I/O actions is that if they fall into the main function, they are performed." But in the following example, 'greet' never returns and therefore nothing should be printed. import Control.Monad main = greet greet = forever $ putStrLn "Hello World!" Or maybe I should ask: what does it mean to "fall into the main function"?

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  • Problem with java and conditional (game of life)

    - by Muad'Dib
    Hello everybody, I'm trying to implement The Game of Life in java, as an exercise to learn this language. Unfortunately I have a problem, as I don't seem able to make this program run correctly. I implemented a torodial sum (the plane is a donut) with no problem: int SumNeighbours (int i, int j) { int value = 0; value = world[( i - 1 + row ) % row][( j - 1 + column ) % column]+world[( i - 1 + row ) % row][j]+world[( i - 1 + row ) % row][( j + 1 ) % column]; value = value + world[i][( j - 1 + column ) % column] + world[i][( j + 1 ) % column]; value = value + world[( i + 1 ) % row][( j - 1 + column ) % column] + world[( i + 1 ) % row][j]+world[ ( i+1 ) % row ][( j + 1 ) % column]; return value; } And it sums correctly when I test it: void NextWorldTest () { int count; int [][] nextWorld = new int[row][row]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); } System.out.println(); } world=nextWorld; } Unfortunately when I add the conditions of game of life (born/death) the program stop working correctly, as it seems not able anymore to count correctly the alive cells in the neighborhood. It counts where there are none, and it doesn't count when there are some. E.g.: it doesn't count the one below some living cells. It's a very odd behaviour, and it's been giving me a headache for 3 days now... maybe I'm missing something basic about variables? Here you can find the class. void NextWorld () { int count; int [][] nextWorld = new int[row][column]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); if ( ( world[i][j] == 0) && ( count == 3 ) ) { nextWorld[i][j] = 1; } else if ( ( world[i][j] == 1 ) && ( (count == 3) || (count == 2) )) { nextWorld[i][j] = 1; } else { nextWorld[i][j]=0; } } System.out.println(); } world=nextWorld; } } Am I doing something wrong? Below you can find the full package. package com.GaOL; public class GameWorld { int [][] world; int row; int column; public int GetRow() { return row; } public int GetColumn() { return column; } public int GetWorld (int i, int j) { return world[i][j]; } void RandomGen (int size, double p1) { double randomCell; row = size; column = size; world = new int[row][column]; for (int i = 0; i<row; i++ ) { for (int j = 0; j<column; j++ ) { randomCell=Math.random(); if (randomCell < 1-p1) { world[i][j] = 0; } else { world[i][j] = 1; } } } } void printToConsole() { double test = 0; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { if ( world[i][j] == 0 ) { System.out.print(" "); } else { System.out.print(" * "); test++; } } System.out.println(""); } System.out.println("ratio is " + test/(row*column)); } int SumNeighbours (int i, int j) { int value = 0; value = world[( i - 1 + row ) % row][( j - 1 + column ) % column]+world[( i - 1 + row ) % row][j]+world[( i - 1 + row ) % row][( j + 1 ) % column]; value = value + world[i][( j - 1 + column ) % column] + world[i][( j + 1 ) % column]; value = value + world[( i + 1 ) % row][( j - 1 + column ) % column] + world[( i + 1 ) % row][j]+world[ ( i+1 ) % row ][( j + 1 ) % column]; return value; } void NextWorldTest () { int count; int [][] nextWorld = new int[row][row]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); } System.out.println(); } world=nextWorld; } void NextWorld () { int count; int [][] nextWorld = new int[row][column]; nextWorld = world; for (int i=0; i<row; i++) { for (int j=0; j<column; j++) { count = SumNeighbours(i,j); System.out.print(" " + count + " "); if ( ( world[i][j] == 0) && ( count == 3 ) ) { nextWorld[i][j] = 1; } else if ( ( world[i][j] == 1 ) && ( (count == 3) || (count == 2) )) { nextWorld[i][j] = 1; } else { nextWorld[i][j]=0; } } System.out.println(); } world=nextWorld; } } and here the test class: package com.GaOL; public class GameTestClass { public static void main(String[] args) { GameWorld prova = new GameWorld(); prova.RandomGen(10, 0.02); for (int i=0; i<3; i++) { prova.printToConsole(); prova.NextWorld(); } } }

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  • Looking for a good world map generation algorithm

    - by FalconNL
    I'm working on a Civilization-like game and I'm looking for a good algorithm for generating Earth-like world maps. I've experimented with a few alternatives, but haven't hit on a real winner yet. One option is to generate a heightmap using perlin noise and add water at a level so that about 30% of the world is land. While perlin noise (or similar fractal-based techniques) are frequently used for terrain and is reasonably realistic, it doesn't offer much in the way of control over the number, size and position of the resulting continents, which I'd like to have from a gameplay perspective. See http://farm3.static.flickr.com/2792/4462870263_ff26c40365_o.jpg for an example (sorry, can't post pictures yet). A second option is to start with a randomly positioned one-tile seed (I'm working on a grid of tiles), determine the desired size for the continent and each turn add a tile that is horizontally or vertically adjacent to the existing continent until you've reached the desired size. Repeat for the other continents. This technique is part of the algorithm used in Civilization 4. The problem is that after placing the first few continents, it's possible to pick a starting location that's surrounded by other continents, and thus won't fit the new one. Also, it has a tendency to spawn continents too close together, resulting in something that looks more like a river than continents. See http://farm5.static.flickr.com/4069/4462870383_46e86b155c_o.jpg for an example. Does anyone happen to know a good algorithm for generating realistic continents on a grid-based map while keeping control over their number and relative sizes?

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  • Android RestTemplate Ok on emulator but fails on real device

    - by Hossein
    I'm using spring RestTemplate and it works perfect on emulator but if I run my app on real device I get HttpMessageNotWritableException ............ nested exception is java.net.SocketException: Broken pipe Here is some lines of my code(keep in mind my app works perfect on emulator) ............ LoggerUtil.logToFile(TAG, "url is [" + url + "]"); LoggerUtil.logToFile(TAG, "NetworkInfo - " + connectivityManager.getActiveNetworkInfo()); ResponseEntity<T> responseEntity = restTemplate.exchange(url, HttpMethod.POST, requestEntity, clazz); ............. I know my device's network works perfect because all other applications on my device are working and also using device browser I'm able to connect to my server so my server is available. My server is up and running and my device is able to connect to my server so why I get java.net.SocketException: Broken pipe ?!!!!!!! Before I call restTemplate.exchange() I log NetworkInfo and it looks ok -type: WIFI -status: CONNECTED/CONNECTED -isAvailable: true Thanks in advance. Update: It is really weird Even if I use HttpURLConnection, it works perfectly on emulator but on real device I get 400 Bad Request Here is my code HttpURLConnection con = null; try { String url = ....; LoggerUtil.logToFile(TAG, "url [" + url + "]" ); con = (HttpURLConnection) new URL(url).openConnection(); con.setRequestMethod("POST"); con.setRequestProperty("Connection", "Keep-Alive"); con.setDoInput(true); con.setDoOutput(true); con.setUseCaches(false); con.connect(); LoggerUtil.logToFile(TAG, "con.getResponseCode is " + con.getResponseCode()); LoggerUtil.logToFile(TAG, "con.getResponseMessage is " + con.getResponseMessage()); } catch(Throwable t){ LoggerUtil.logToFile(TAG, "*** failed [" + t + "]" ); } in log file I see con.getResponseCode is 400 con.getResponseMessage is Bad Request

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  • Flash movies in inactive browser tabs pause or don't execute in real time

    - by ZenBlender
    I'm noticing some unexpected behavior. Some time in the last few months, a change in either Firefox, the Flash player, or both, has made it so that Flash movies that are in inactive browser tabs no longer execute in real time. They appear to still execute, but only in bursts, and not in a predictable way. This is a problem because I develop a Flash-based (Actionscript 2.0, Flash CS3) multiplayer game that maintains a network connection and allows players to chat, etc. Many of our players complain about Firefox crashing while playing the game. I have noticed it too, not too frequently, but it crashes several times a week. (Firefox crashes, I do not get a message from Flash player that indicates an infinite loop or problem in my code) My theory is that this new behavior is causing crashes when there is a lot of activity in my game, leading to lots of unhandled network traffic for my game getting buffered before Firefox/Flash will give it a chance to execute. Maybe this leads to a buffer overflow or missing packets, and as a result, something crashes. At times I will switch back to the tab that is running my game and discover a display bug, which looks as though Flash has simply failed to execute something that it was supposed to. I would assume this new behavior is on purpose, for example to prevent all the Flash-based advertisements in inactive tabs from executing and therefore killing performance. In a quick test on Chrome (5.0.342.9 beta), this "pausing" of Flash seems to be there as well, but somehow it seems much less of a problem. My users have only complained about Firefox crashing, not other browsers. My machine: Windows 7 x64 Firefox 3.6.3 Flash Player 10.1.50.426 My game: triplejack.com Any ideas? Ideally I'd like to disable this behavior for my Flash game so it can execute in real time even when in an inactive tab. Thanks for any help!

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  • Creating a Hello World library function in assembly and calling it from C#

    - by Filip Ekberg
    Let's say we use NASM as they do in this answer: how to write hellow world in assembly under windows. I got a couple of thoughts and questions regarding assembly combined with c# or any other .net languages for that matter. First of all I want to be able to create a library that has the following function HelloWorld that takes this parameter: Name In C# the method signature would looke like this: void HelloWorld(string name) and it would print out something like Hello World from name I've searched around a bit but can't find that much good and clean material for this to get me started. I know some basic assembly from before mostly gasthough. So any pointers in the right direction is very much apprechiated. To sum it up Create a function in ASM ( NASM ) that takes one or more parameters Compile and create a library of the above functionality Include the library in any .net language Call the included library function Bonus features How does one handle returned values? Is it possible to write the ASM-method inline? When creating libraries in assembly or c, you do follow a certain "pre defined" way, the c calling convetion, correct?

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  • Change the playback rate of a track in real time on Android

    - by android_dev
    Hello, I would like to know if somebody knows a library to changing the playback rate of a track in real time. My idea is to load a track and change its playback rate to half or double. Firstly, I tried with MusicPlayer but is was not possible at all and then I tried with SoundPool. The problem is that with SoundPool I can´t change the rate once the track is loaded. Here is the code I am using (proof of concept): float j = 1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button b = (Button)findViewById(R.id.Button01); b.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { j = (float) (j +.5); } }); AssetFileDescriptor afd; try { SoundPool sp = new SoundPool(1, AudioManager.STREAM_MUSIC, 0); afd = getAssets().openFd("wav/sample.wav"); int id = sp.load(afd, 1); sp.play(id, 1, 1, 1, 0, j); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } When I press the button, the playback rate should increase but it does not happen. Any idea of how change the rate in real time? Thanks in advance.

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  • Interactive World Map, highlight countries on mouseover

    - by BrenGG
    I need to create an interactive world map on the front page of a site, the view portal will be about 650x200 pixels. The interactivity would include the following, mouse-over a country would highlight (the countries are will literally be filled with "red" for example) that country and display the countries' name (preferably text in a div), I will also be linking the highlighting event with a that will highlight a country when selected. I am having a difficult time finding a suitable solution, I refuse to use or learn a proprietry technology such as flash so it is not an option. I created a simple mockup using openlayers and a custom map image but the countries' markers load too slowly in IE6. Also svg seems too large, as I tried to use RaphaelJS, but abondoned it when I realised the world map data is 1.2mb which is totally un acceptable for the front page of a site.. I am really at a loss on how I am going to do this, my last resort is to manually create 250+ (however many countries there are) pngs and apply mouseover events to hotspots in the image... but this is probably going to be a dead end too.. desperately seeking a solution, any helpful comments will be appreciated!

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  • Group vs role (Any real difference?)

    - by Ondrej
    Can anyone tell me, what's the real difference between group and role? Ive been trying to figure this out for some time now and the more information I read, the more I get the sence, that this is brought up just to confuse people and there is no proper difference in this. Both can do the other one's job. Ive always used a group to manage users and their access rights. Recently, I've come accross an administration software, where is a bunch of users. Each user can have assigned a module (whole system is split into a few parts called modules ie. Administration module, Survey module, Orders module, Customer module). On top of it, each module have a list of functionalities, that can be allowed or denied for each user. So let's say, a user John Smith can access module Orders and can edit any order, but havent given a right to delete any of them. If there was more users with the same competency, I would use a group to manage that. I would aggregate such users into the same group and assign access rights to modules and their functions to the group. All users in the same group would have the same access rights. Why call it a group and not role? I don't know, I just feel it that way. It seems to me, that simply it just doesnt really matter :] But I still would like to know the real difference. What about you guys? Any suggestions why this should be rather called role than group or the other way round? Thanks to everyone.

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  • How can I generate an "unlimited" world?

    - by snowlord
    I would like to create a game with an endless (in reality an extremely large) world in which the player can move about. Whether or not I will ever get around to implement the game is one matter, but I find the idea interesting and would like some input on how to do it. The point is to have a world where all data is generated randomly on-demand, but in a deterministic way. Currently I focus on a large 2D map from which it should be possible to display any part without knowledge about the surrounding parts. I have implemented a prototype by writing a function that gives a random-looking, but deterministic, integer given the x and y of a pixel on the map (see my recent question about this function). Using this function I populate the map with "random" values, and then I smooth the map using a simple filter based on the surrounding pixels. This makes the map dependent on a few pixels outside its edge, but that's not a big problem. The final result is something that at least looks like a map (especially with a good altitude color map). Given this, one could maybe first generate a coarser map which is used to generate bigger differences in altitude to create mountain ranges and seas. Anyway, that was my idea, but I am sure that there exist ways to do this already and I also believe that given the specification, many of you can come up with better ideas. EDIT: Forgot the link to my question.

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  • Help me refactor my World Cup Challenge Script

    - by kylemac
    I am setting up a World Cup Challenge between some friends, and decided to practice my Ruby and write a small script to automate the process. The Problem: 32 World Cup qualifiers split into 4 tiers by their Fifa ranking 8 entries Each entry is assigned 1 random team per tier Winner takes all :-) I wrote something that suffices yet is admittedly brute force. But, in my attempt to improve my Ruby, I acknowlege that this code isn't the most elegant solution around - So I turn to you, the experts, to show me the way. It may be more clear to check out this gist - https://gist.github.com/91e1f1c392bed8074531 My Current (poor) solution: require 'yaml' @teams = YAML::load(File.open('teams.yaml')) @players = %w[Player1 Player2 Player3 Player4 Player5 Player6 Player7 Player8] results = Hash.new players = @players.sort_by{rand} players.each_with_index do |p, i| results[p] = Array[@teams['teir_one'][i]] end second = @players.sort_by{rand} second.each_with_index do |p, i| results[p] << @teams['teir_two'][i] end third = @players.sort_by{rand} third.each_with_index do |p, i| results[p] << @teams['teir_three'][i] end fourth = @players.sort_by{rand} fourth.each_with_index do |p, i| results[p] << @teams['teir_four'][i] end p results I am sure there is a better way to iterate through the tiers, and duplicating the @players object ( dup() or clone() maybe?) So from one Cup Fan to another, help me out.

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  • mod_rewrite: no access to real files and directories

    - by tshabalala
    Hello. I use mod_rewrite/.htaccess for pretty URLs. I forward all the requests to my index.php, like this: RewriteRule ^/?([a-zA-Z0-9/-]+)/?$ /index.php [NC,L] The index.php then handles the requests. I'm also using this condition/rule to eliminate trailing slashes (or rather rewrite them to the URL without a trailing slash, with a 301 redirect; I'm doing this to avoid duplicate content and because I like no trailing slashes better): RewriteCond %{HTTP_HOST} !^\.localhost$ [NC] RewriteRule ^(.+)/$ http://%{HTTP_HOST}/$1 [R=301,L] This works well, except that I now get an infinite loop when trying to access a (real) directory (the rewrite rule removes the trailing slash, the server adds it again, ...). I solved this by setting the DirectorySlash directive to Off: DirectorySlash Off I don't know how good this solution is, I don't feel too confident about it tbh. Anyway, what I'd like to do is completely ignore "real" files and directories, since I don't need them and I only use pretty URLs with "virtual" files/directories anyway. This would allow me to avoid the DirectorySlash workaround/hack too. Is this possible? Thanks!

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  • Projecting an object into a scene based on world coordinates only

    - by user354862
    I want to place a 3D image into a scene base on world/global coordinates. I have an image of a scene. The image was captures at some global coordinate (x1, y1, z1). I am given an object that needs to be placed into this scene based on its global coordinate (x2, y2, y3). This object needs to be projected into the scene accurately similarly to perspective projection. An example may help to make this clear. Imagine there is a parking lot with some set of global coordinates. A picture is taken of a portion of the parking lot. The coordinates from the spot where the image was taken is recorded. The goal is to place a virtual vehicle into this image using the global coordinates for that vehicle. Because the global cooridnates for the vehicle may not be in the fov of the global coordinates for the image I am assuming that I will need the image coordinates, angle and possibly fov. 3D graphics is not my area so I have been looking at http://en.wikipedia.org/wiki/Perspective_projection#Perspective_projection. I have also been looking at Matrix3DProjection which seems to possibly be what I am looking for but it only works in Silverlight and I am trying to do this in WPF. In my mind it appears I need to determine the (X,Y,Z) coordinates that are in the fov of the image, determine the world coordinate to pixel conversion and then accurately project the vehicle into the image giving it the correct perspective such that is looks 3D i.e smaller the further away bigger closer Is there a function within WPF that can help with this or will I need to re-learn matrices and do this by hand?

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