Search Results

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

Page 52/730 | < Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >

  • Error when connecting to hello world yesod example on Windows 8

    - by reltone
    I start the executable (after building it with cabal) and it says "Application launched, listening on port 3000." Next I connect to it with my web browser and the console says "threadWaitRead requires -threaded on Windows, or use System.IO.hWaitForInput." The web browser never connects. Not sure what this is actually recommending I do to resolve the problem. {-# LANGUAGE TypeFamilies, QuasiQuotes, MultiParamTypeClasses, TemplateHaskell, OverloadedStrings #-} import Yesod data HelloWorld = HelloWorld mkYesod "HelloWorld" [parseRoutes| / HomeR GET |] instance Yesod HelloWorld getHomeR :: Handler RepHtml getHomeR = defaultLayout [whamlet|Hello World!|] main :: IO () main = warpDebug 3000 HelloWorld

    Read the article

  • Real World Application of XPath & XSLT

    - by Knowledge Craving
    Can any professional please specify some real world application, where he / she has used this XPath & XSLT for any logic / view? It creates a great query among some of the people I've communicated with, and so I myself also wants to know about this. I wish that this question will create a starting point from where new developers will take home some practical experience. Any help is greatly appreciated.

    Read the article

  • Android "hello world" - versions

    - by Ianb
    Starter question: My "Hello World" attempt won't run, ("No compatible targets were found"), I think this is bacause I selected the latest version for my project (2.2), and the highest AVD version is 2.0.1. Does this make sense? Can I change my project version (haven't been able to find a way to do this), or do I have to start again? If the versions are not backwards compatible, what is the best version to use for the majority of Android devices out there? Thanks

    Read the article

  • Type signature "Maybe a" doesn't like "Just [Event]"

    - by sisif
    I'm still learning Haskell and need help with the type inference please! Using packages SDL and Yampa I get the following type signature from FRP.Yampa.reactimate: (Bool -> IO (DTime, Maybe a)) and I want to use it for: myInput :: Bool -> IO (DTime, Maybe [SDL.Event]) myInput isBlocking = do event <- SDL.pollEvent return (1, Just [event]) ... reactimate myInit myInput myOutput mySF but it says Couldn't match expected type `()' against inferred type `[SDL.Event]' Expected type: IO (DTime, Maybe ()) Inferred type: IO (DTime, Maybe [SDL.Event]) In the second argument of `reactimate', namely `input' In the expression: reactimate initialize input output process I thought Maybe a allows me to use anything, even a SDL.Event list? Why is it expecting Maybe () when the type signature is actually Maybe a? Why does it want an empty tuple, or a function taking no arguments, or what is () supposed to be?

    Read the article

  • Population count of rightmost n integers

    - by Jason Baker
    I'm implementing Bagwell's Ideal Hash Trie in Haskell. To find an element in a sub-trie, he says to do the following: Finding the arc for a symbol s, requires ?nding its corresponding bit in the bit map and then counting the one bits below it in the map to compute an index into the ordered sub-trie. What is the best way to do this? It sounds like the most straightforward way of doing this is to select the bits below that bit and do a population count on the resulting number. Is there a faster or better way to do this?

    Read the article

  • (newbie) type signature "Maybe a" doesn't like "Just [Event]"

    - by sisif
    i'm still learning Haskell and need help with the type inference please! using packages SDL and Yampa i get the following type signature from FRP.Yampa.reactimate: (Bool -> IO (DTime, Maybe a)) and i want to use it for: myInput :: Bool -> IO (DTime, Maybe [SDL.Event]) myInput isBlocking = do event <- SDL.pollEvent return (1, Just [event]) ... reactimate myInit myInput myOutput mySF but it says Couldn't match expected type `()' against inferred type `[SDL.Event]' Expected type: IO (DTime, Maybe ()) Inferred type: IO (DTime, Maybe [SDL.Event]) In the second argument of `reactimate', namely `input' In the expression: reactimate initialize input output process i thought "Maybe a" allows me to use anything, even a SDL.Event list? why is it expecting "Maybe ()" when the type signature is actually "Maybe a"? why does it want an empty tuple, or a function taking no arguments, or what is () supposed to be?

    Read the article

  • Last element not getting insert in Tree

    - by rdk1992
    So I was asked to make a Binary Tree in Haskell taking as input a list of Integers. Below is my code. My problem is that the last element of the list is not getting inserted in the Tree. For example [1,2,3,4] it only inserts to the tree until "3" and 4 is not inserted in the Tree. data ArbolBinario a = Node a (ArbolBinario a) (ArbolBinario a) | EmptyNode deriving(Show) insert(x) EmptyNode= insert(tail x) (Node (head x) EmptyNode EmptyNode) insert(x) (Node e izq der) |x == [] = EmptyNode --I added this line to fix the Prelude.Head Empty List error, after I added this line the last element started to be ignored and not inserted in the tree |head x == e = (Node e izq der) |head x < e = (Node e (insert x izq) der) |head x > e = (Node e izq (insert x der)) Any ideas on whats going on here? Help is much appreciated

    Read the article

  • Cartesian Plane

    - by NuNu
    I'm trying to define a function in Haskell that takes an integer argument c and returns the list of all points on the cartesian plane of the form (x/c,y/c) where x and y are integers. x/c is between -2 and 1 and y/r is between -1 and 1 This is what I've gotten so far which I'm almost sure is right but I'm getting a parse error on input = when I run it particularly at this line: cart xs ys c = [(y/c,x/c) | x <- xs, y <- ys] plane :: Int -> [a] plane c = cart [-1*c .. 1*c] [-2*c .. 1*c] c cart xs ys c = [(y/c,x/c) | x <- xs, y <- ys] A sample output would be: plane 1 would generate: [(-2.0, -1.0), (-1.0, -1.0), ( 0.0, -1.0), ( 1.0, -1.0), (-2.0, 0.0), (-1.0, 0.0), ( 0.0, 0.0), ( 1.0, 0.0), (-2.0, 1.0), (-1.0, 1.0), ( 0.0, 1.0), ( 1.0, 1.0)] Anyone have any idea how I can fix this! Thanks

    Read the article

  • Multiplying numbers on horizontal, vertial, and diagonal lines

    - by untwisted
    I'm currently working on a project Euler problem (www.projecteuler.net) for fun but have hit a stumbling block. One of the problem provides a 20x20 grid of numbers and asks for the greatest product of 4 numbers on a straight line. This line can be either horizontal, vertical, or diagonal. Using a procedural language I'd have no problem solving this, but part of my motivation for doing these problems in the first place is to gain more experience and learn more Haskell. As of right now I'm reading in the grid and converting it to a list of list of ints, eg -- [[Int]]. This makes the horizontal multiplication trivial, and by transposing this grid the vertical also becomes trivial. The diagonal is what is giving me trouble. I've thought of a few ways where I could use explicit array slicing or indexing, to get a solution, but it seems overly complicated and hackey. I believe there is probably an elegant, functional solution here, and I'd love to hear what others can come up with.

    Read the article

  • Can I config different VIP per service pointing same Real servers with Cisco ACE?

    - by Kamome
    I'm using Cisco ACE Module with Cisco Catalyst 6504. There are 2 real servers connected to Switch, and runs three different services. (TCP 82, 83 and 84) I have to use three different URLs per service. (for example, a.com for TCP 82, b.com for TCP 83 and c.com for TCP 84) Therefore, I need three IPs. The problem is, is it possible that configure 3 different VIPs with same real servers with Cisco ACE Module? I mean, if VIPs are 1.1.1.1, 2.2.2.2, 3.3.3.3 and real servers are 4.4.4.4, 5.5.5.5, can I configure as following : VIP 1.1.1.1:82 Real Server 4.4.4.4:82, 5.5.5.5:82 VIP 2.2.2.2:83 Real Server 4.4.4.4:83, 5.5.5.5:83 VIP 3.3.3.3:84 Real Server 4.4.4.4:84, 5.5.5.5:84 I think, logically, it's possible. But is it REALLy possible?

    Read the article

  • Getting real-time market/stock quotes in C#/Java

    - by David Menard
    Hey, I would like to make an program that acts like a big filter for stocks. To do so, I need to have real-time (or delayed) quotes from the market. I started getting stock quotes by requesting pages from yahoo, accordingand parsing the html to the ticker, and parsing the html. I was wondering how to do this requesting and parsing html. Is there some way I can request only the stock quotes and its info? I know some applications do this, and I am very curious how they do it, because requesting web pages and parsing them is very time-consuming. Thanks, Dave

    Read the article

  • robocode engine: how to design (write) the runtime engine -- the robot world

    - by Bob
    IBM has (had) a free learn-Java program called RoboCode, in which custom robots could be written that would then do battle in a 2D space. I would like to write the environment that supports such robots, but don't know what pattern or design to use. Each robot is a thread. Each thread is given a certain (indeterminate) amount of run-time by the JRE. A robot world engine would start by building a list of the players/robots, then enter a loop that allows each player in turn to do whatever it likes: move forward, turn left, fire toward the northwest corner, whatever. Each robot is also informed of events of interest: an enemy or several enemies are within range, it has been hit by a bullet, etc. The combination of handling threads that are also event listeners (are they also producers?) confuses me; it seems that there's more to the game engine. Even some general ideas would help. TIA.

    Read the article

  • Real world uses of Reflection.Emit

    - by Ryu
    In all the books I've read on reflection they often say that there aren't many cases where you want to generate IL on the fly, but they don't give any examples of where it does make sense. After seeing Reflection.Emit as a job requirement for a gaming company I was curious where else it's being used. I'm now wondering if there are any situations you've seen in the real world were it was the best solution to the problem. Perhaps it is used as an implementation to a design pattern? Note I imagine PostSharp / AOP uses it.

    Read the article

  • iPhone MapKit - Go "Around the World" ?

    - by Chris
    I have an App that is using MapKit. I am dropping pins and everything else, but when I zoom out to view the entire world, it does not let me go past the the middle of the Pacific Ocean. If I am viewing California and want to go to China, I have to scroll all the way East to view it. Is there a setting that I need to turn on, or is this just the way it is? I do note that this is how the actual Maps App works, so I might presume that this setting cannot be changed...

    Read the article

  • How do i translate movement on the Canvas3D to movement in the virtual 3D world

    - by Coder
    My goal is to move a shape in the virtual world in such a way so that it ends up where the mouse pointer is on the canvas. What i have: -mouse position (x,y) on a Canvas3D object -Point3d object of where a pick ray starting from the Canvas3D viewport intersects with the first scene object. (point in 3D space of where i want to start the drag) What i want: -Some way to translate the Point3d's coordinates so that the initial point of intersection (the Point3d object) is always overlapping the the mouse position on the canvas (same as when i used the pick ray to determine what the user clicked on from the Canvas3D object). Thanks!

    Read the article

  • MVC in a Google App Engine Java world

    - by thatismatt
    I'm coming to Java from C# & ASP.NET MVC, I'd love to find an equivalent in the Java world that I could use on the Google App Engine. I've already started to have a play with FreeMarker and even made the first steps towards writing a very simple framework. Ideally I wouldn't have to do all the hard work though, someone must have done this already! So my question is - what frameworks are there out there that would be familiar for me coming from ASP.NET MVC and I could use them on Google App Engine for Java. The key things I'd want are: Simple Routing - /products/view/1 gets mapped to the view action of the products controller with the productid of 1 Template Engine - some way of easily passing 'ViewData' to the view, and from the view easily accessing it, ideally I'd love to avoid anything that is too XMLy (thus why I like FreeMarker).

    Read the article

  • How to CompareTo two Object without known about their real type

    - by Kamil
    I have to implement a one linked list but it should put object in appropriate position. Everything was OK when I use it in conjunction with specific class, but when I tried make it universal and argument of method insert was Object some problem appeared. When I want to input Object in right position I should use CompareTo method, but there isn't method in Object class! The problem is how to compare two object elements without known about their real types. Maybe I should use generic class type? But what about CompareTo? Or maybe combine with Element class and place CompareTo there? I suppose it is feasible. :) public void insert(Object o) { Element el = new Element(o); // initializing and setting iterators while(!it.isDone() && ((it.current().getValue())).CompareTo(o)<0) // it.current() returns Element of List { //move interators } //... }

    Read the article

  • Project ideas for automated deduction/automated theorem proving?

    - by wsh
    Dear Stack Overflow brethren, I'm a second-semester junior who will embark upon my thesis soon, and I have an interest in automated deduction and automated theorem provers. As in, I'd like to advance the art in some way (I don't mean that pretentiously, but I do want to do something productive). I've Googled pretty far and wide and so far few promising ideas have emerged. There are a few student project idea pages, but most seem either horribly outdated or too advanced (I was originally going to attempt to synthesize postmodernist thought (hahaha) and abstract its logical content, build a complete and consistent model (if possible, of course), and attempt to automate it, grounding said model as possible in a nonstandard logic a la these. My advisor thought that gave postmodernist thought too much credit (a while ago I reimplemented the Postmodernism Generator in Haskell with Parsec, so that is in part where the idea came from); I am tempted to concur.) So, yeah. Does anyone have ideas? I apologize if there is some obvious gap in my approach here/if I haven't appropriately done my homework (and if there is one, please tell me!), but in large part I don't even know where to start, and thank you for reading all that.

    Read the article

  • mtl, transformers, monads-fd, monadLib, and the paradox of choice

    - by yairchu
    Hackage has several packages for monad transformers: mtl: Monad transformer library transformers: Concrete functor and monad transformers monads-fd: Monad classes, using functional dependencies monads-tf: Monad classes, using type families monadLib: A collection of monad transformers. mtl-tf: Monad transformer library using type families mmtl: Modular Monad transformer library mtlx: Monad transformer library with type indexes, providing 'free' copies. compose-trans: Composable monad transformers (and maybe I missed some) Which one shall we use? mtl is the one in the Haskell Platform, but I keep hearing on reddit that it's uncool. But what's bad about choice anyway, isn't it just a good thing? Well, I saw how for example the authors of data-accessor had to make all these to cater to just the popular choices: data-accessor-monadLib library: Accessor functions for monadLib's monads data-accessor-monads-fd library: Use Accessor to access state in monads-fd State monad class data-accessor-monads-tf library: Use Accessor to access state in monads-tf State monad type family data-accessor-mtl library: Use Accessor to access state in mtl State monad class data-accessor-transformers library: Use Accessor to access state in transformers State monad I imagine that if this goes on and for example several competing Arrow packages evolve, we might see something like: spoonklink-arrows-transformers, spoonklink-arrows-monadLib, spoonklink-tfArrows-transformers, spoonklink-tfArrows-monadLib, ... And then I worry that if spoonklink gets forked, Hackage will run out of disk space. :) Questions: Why are there so many monad transformer packages? Why is mtl [considered] uncool? What are the key differences? Most of these seemingly competing packages were written by Andy Gill and are maintained by Ross Paterson. Does this mean that these packages are not competing but rather work together in some way? And do Andy and Ross consider any of their own packages as obsolete? Which one should me and you use?

    Read the article

  • Eclipse IDE's Hello World Cheatsheet seems to have a mistake

    - by Sean
    Hey guys, Just a warning: I'm completely new to Java and am trying to teach myself Android programming. I installed the Eclipse IDE today and tried to walk through the first Java Hello World "cheat sheet," and it didn't work! I was really quite surprised. When it asked me to select the checkbox to create the main() method, there wasn't anything on-screen that looked like a checkbox with "main()" or "method" next to it, so I guessed that maybe what they meant was the "Modifiers" radio button. So I left that checked for "public." It didn't compile and I got red X's next to every folder in my Package Explorer. Has anybody else had this problem? Thanks!

    Read the article

< Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >