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  • What's the *right* way to handle a POST in FP?

    - by Malvolio
    I'm just getting started with FP and I'm using Scala, which may not be the best way, since I can always fall back to an imperative style if the going gets tough. I'd just rather not. I've got a very specific question that points to a broader lacuna in my understanding of FP. When a web application is processing a GET request, the user wants information that already exists on the web-site. The application only has to process and format the data in some way. The FB way is clear. When a web application is processing a POST request, the user wants change the information held on the site. True, the information is not typically held in application variables, it's in a database or a flat-file, but still, I get the feeling I'm not grokking FP properly. Is there a pattern for handling updates to static data in an FP language? My vague picture of this is that the application is handed the request and the then-current site state. The application does its thing and returns the new site-state. If the current site-state hasn't changed since the application started, the new state becomes the current state and the reply is sent back to the browser (this is my dim image of Clojure's style); if the current state has been changed (by another thread, well, something else happens ...

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  • What are the benefits of `while(condition) { //work }` and `do { //work } while(condition)`?

    - by Shaharyar
    I found myself confronted with an interview question where the goal was to write a sorting algorithm that sorts an array of unsorted int values: int[] unsortedArray = { 9, 6, 3, 1, 5, 8, 4, 2, 7, 0 }; Now I googled and found out that there are so many sorting algorithms out there! Finally I could motivate myself to dig into Bubble Sort because it seemed pretty simple to start with. I read the sample code and came to a solution looking like this: static int[] BubbleSort(ref int[] array) { long lastItemLocation = array.Length - 1; int temp; bool swapped; do { swapped = false; for (int itemLocationCounter = 0; itemLocationCounter < lastItemLocation; itemLocationCounter++) { if (array[itemLocationCounter] > array[itemLocationCounter + 1]) { temp = array[itemLocationCounter]; array[itemLocationCounter] = array[itemLocationCounter + 1]; array[itemLocationCounter + 1] = temp; swapped = true; } } } while (swapped); return array; } I clearly see that this is a situation where the do { //work } while(cond) statement is a great help to be and prevents the use of another helper variable. But is this the only case that this is more useful or do you know any other application where this condition has been used?

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  • suggestions on syntax to express mathematical formula concisely

    - by aaa
    hello. I am developing functional domain specific embedded language within C++ to translate formulas into working code as concisely and accurately as possible. I post prototype in the comment, it is about 2 hundred lines long. Right now my language looks something like this (well, actually is going to look like): // implies two nested loops j=0:N, i=0,j (range(i) < j < N)[T(i,j) = (T(i,j) - T(j,i))/e(i+j)]; // implies summation over above expression sum(range(i) < j < N))[(T(i,j) - T(j,i))/e(i+j)]; I am looking for possible syntax improvements/extensions or just different ideas about expressing mathematical formulas as clearly and precisely as possible (in any language, not just C++). Can you give me some syntax examples relating to my question which can be accomplished in your language of choice which consider useful. In particular, if you have some ideas about how to translate the above code segments, I would be happy to hear them. Thank you just to clarify and give actual formula, my short-term goal is to express the following expression concisely where values in <> are already computed as 4-dimensional array

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  • Is there any reason for a blocking call to winsock send() function on Vista to return immediately ?

    - by ivymike
    Hi All, Is there any reason for a blocking call to winsock's send() function on Vista to return immediately ? It works with expected delay on XP and below. I'm wondering if this has got anything to do with auto-tuning feature of Vista. Code: char *pBuffer; // pointer to data int bytes; // total size int i = 0, j=0; while (i < bytes) { j = send(m_sock, pBuffer+i, bytes-i, 0); i+=j; } Thanks, Pavan

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  • Losing a programmer, what steps to take?

    - by Zak
    One of the programmers on our team is leaving for greener pastures. We will be going from 6 to 5. What steps should we take to ensure our development process continues to run smoothly, potentially while integrating in new blood. We are currently working on a short release cycle with iterative development. Design - code - review. The person leaving was the most senior dev on the team, and would often give lots of feedback to the rest of the team, especially during the design phase.

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  • Avoiding dependency carrying

    - by dotnetdev
    When coding, I often come across the following pattern: -A method calls another method (Fine), but the method being called/callee takes parameters, so in the wrapping method, I pass in parameters. Problem is, this dependency carrying can go on and on. How could I avoid this (any sample code appreciated)? Thanks

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  • When will a TCP network packet be fragmented at the application layer?

    - by zooropa
    When will a TCP packet be fragmented at the application layer? When a TCP packet is sent from an application, will the recipient at the application layer ever receive the packet in two or more packets? If so, what conditions cause the packet to be divided. It seems like a packet won't be fragmented until it reaches the Ethernet (at the network layer) limit of 1500 bytes. But, that fragmentation will be transparent to the recipient at the application layer since the network layer will reassemble the fragments before sending the packet up to the next layer, right?

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  • What language is .NET Framework written in?

    - by chester89
    The question I always wanted to ask and was afraid to, actually - what language is .NET Framework written in? I mean library itself. It seems to me that it was C and C++ mostly. (I hope Jon Skeet is reading this one, it`ll be very interesting to hear what he thinks about it)

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  • Is it faster to count down than it is to count up?

    - by Bob
    Our computer science teacher once said that for some reason it is more efficient to count down that count up. For example if you need to use a FOR loop and the loop index is not used somewhere (like printing a line of N * to the screen) I mean that code like this : for (i=N; i>=0; i--) putchar('*'); is better than: for (i=0; i<N; i++) putchar('*'); Is it really true? and if so does anyone know why?

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  • How to see "anti if" movement and its gaol?

    - by Vijay Shanker
    I have a developer for last 3 years, have been using if-else or if-else if statements a lot in my programing habit. And today, I found This link. One obvious sample i put here public void doSomthing(String target, String object){ //validate requests if(target != null && target.trim().length() < 1){ //invalid request; } //further logic } Now, I have seen this sort of check all over the places, libraries. So, I wanted to have a discussion about the worthiness of such a movement. Please let me know your views.

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  • Java Servlet says file does not exist

    - by Austin
    Hello World! I have developed a java servlet that monitors a folder on a network drive for new files then does some actions on them depending on what kind of file it is. It worked in Eclipse when Eclipse and Tomcat were running with each other, but now that I have deployed it onto a server(different machine), the servlet keeps logging that it cannot find the folder to be mapped. The exact same network drive is mapped, and the folder definitely exists. This problem only occurs when the servlet is run on the server, not on the development machine. Thanks! PS: It is a Windows Server 2003 Enterprise Server with Tomcat v6 installed.

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  • Problem when trying to define Show for my Point3D type in Haskell

    - by devoured elysium
    I am trying to define Show for my Point3D type: type Point3D = (Integer, Integer, Integer) instance Show Point3D where show (x,y,z) = "<" ++ (show x) ++ "," ++ (show y) ++ "," ++ (show z) ++ ">" yet I must be missing something in the sintax, as I am always getting an error: Illegal instance declaration for `Show Point3D' (All instance types must be of the form (T t1 ... tn) where T is not a synonym. Use -XTypeSynonymInstances if you want to disable this.) In the instance declaration for `Show Point3D' What am I doing wrong?

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  • How do I clear the text contents of a div in javascript?

    - by Ben
    I'm temporarily adding contents to a div,tempDiv, and adding that to a link which is appended to a div, #contentHere, that's displayed. I need to clear the contents of tempDiv so that the links aren't appended to each other, creating a string of urls that don't link to anywhere. $(document).ready(function(){ $.getJSON("data.php", function(data){ for(i = 0; i < 5; i++){ $("#tempDiv").append(data.justIn[i].dataLink+ ' '); $("#contentHere").append("<a href=\"#tempDiv\">Click to go to the div link</a>"); //I need to clear the contents of tempDiv here } }); }); Solutions to clearing the temporary contents of the div as I go?

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  • Which way to store this data is effective?

    - by Tattat
    I am writing a game, which need a map, and I want to store the map. The first thing I can think of, is using a 2D-array. But the problem is what data should I store in the 2D-array. The player can tap different place to have different reaction. So, I am thinking store a 2D-array with objects, when player click some position, and I find it in the array, and use the object in that array to execute a cmd. But I have a concern that storing lots of object may use lots of memory. So, I am think storing char/int only. But it seems that not enough for me. I want to store the data like that: { Type:1 Color:Green } No matter what color is, if they are all type 1, the have same reactions in logic, but the visual effect is based on the color. So, it is not easy to store using a prue char/int data, unless I make something like this: 1-5 --> all type 1. 1=color green , 2=color red, 3 = color yellow.... ... 6-10 --> all type 2. 2 = color green, 2 = color red ... ... So, do you have any ideas on how to minimize the ram use, but also easy for me to read... ...thx

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  • Java me : Can we retrieve bluetooth address of connected device from an open slave connection ?

    - by Rohit
    Here is a typical sequence of events that occur : Host device opens a service ( Host device accepts and opens all incoming connections) A remote device connects to host device. Now, we have a slave connection open at host device. At host device, I want to know the bluetooth address of remote device. I can always pass it as data from remote to host device, but can I extract it from connection object somehow without any data transfer? Thanks in advance...

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  • Help me sort programing languages a bit

    - by b-gen-jack-o-neill
    Hi, so I asked here few days ago about C# and its principles. Now, if I may, I have some additional general questions about some languages, becouse for novice like me, it seems a bit confusing. To be exact I want to ask more about language functions capabilities than syntax and so. To be honest, its just these special functions that bothers me and make me so confused. For exmaple, C has its printf(), Pascal has writeln() and so. I know in basic the output in assembler of these funtions would be similiar, every language has more or less its special functions. For console output, for file manipulation, etc. But all these functions are de-facto part of its OS API, so why is for example in C distinguished between C standard library functions and (on Windows) WinAPI functions when even printf() has to use some Windows feature, call some of its function to actually show desired text on console window, becouse the actuall "showing" is done by OS. Where is the line between language functions and system API? Now languages I dont quite understand - Python, Ruby and similiar. To be more specific, I know they are similiar to java and C# in term they are compiled into bytecode. But, I do not unerstand what are its capabilities in term of building GUI applications. I saw tutorial for using Ruby to program GUI applications on Linux and Windows. But isn´t that just some kind of upgrade? I mean fram other tutorials It seemed like these languages was first intended for small scripts than building big applications. I hope you understand why I am confused. If you do, please help me sort it out a bit, I have no one to ask.

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  • Permuting output of a tree of closures

    - by yan
    This a conceptual question on how one would implement the following in Lisp (assuming Common Lisp in my case, but any dialect would work). Assume you have a function that creates closures that sequentially iterate over an arbitrary collection (or otherwise return different values) of data and returns nil when exhausted, i.e. (defun make-counter (up-to) (let ((cnt 0)) (lambda () (if (< cnt up-to) (incf cnt) nil)))) CL-USER> (defvar gen (make-counter 3)) GEN CL-USER> (funcall gen) 1 CL-USER> (funcall gen) 2 CL-USER> (funcall gen) 3 CL-USER> (funcall gen) NIL CL-USER> (funcall gen) NIL Now, assume you are trying to permute a combinations of one or more of these closures. How would you implement a function that returns a new closure that subsequently creates a permutation of all closures contained within it? i.e.: (defun permute-closures (counters) ......) such that the following holds true: CL-USER> (defvar collection (permute-closures (list (make-counter 3) (make-counter 3)))) CL-USER> (funcall collection) (1 1) CL-USER> (funcall collection) (1 2) CL-USER> (funcall collection) (1 3) CL-USER> (funcall collection) (2 1) ... and so on. The way I had it designed originally was to add a 'pause' parameter to the initial counting lambda such that when iterating you can still call it and receive the old cached value if passed ":pause t", in hopes of making the permutation slightly cleaner. Also, while the example above is a simple list of two identical closures, the list can be an arbitrarily-complicated tree (which can be permuted in depth-first order, and the resulting permutation set would have the shape of the tree.). I had this implemented, but my solution wasn't very clean and am trying to poll how others would approach the problem. Thanks in advance.

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  • Detecting the Loopback Adapter

    - by BlueSkies
    What is the best way for detecting whether a network interface is a loopback adapter? The windows API's GetAdaptersInfo and GetAdaptersAddresses state in the documentation that they will return whether an interface is a loopback through the Type (MIB_IF_TYPE_LOOPBACK) but neither of these do for the Microsoft Loopback Adapter at least, it is reported as a standard ethernet interface. I could try checking for the default MAC of the Loopback adapter but this can be easily spoofed. I could check for the name "Microsoft Loopback Adapter" in the description but this may have translation issues and may lead to other issues. IP addresses can also be changed. What is the most robust method for doing this?

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  • What does $this generally mean in PHP?

    - by xczzhh
    I am really new to PHP, so I am kind of confused seeing these different operators all day. Here is some code I came across when watching a video tutorail, I'd appreciate it if some could explain a little bit: function index() { $config = Array( 'protocol' => 'smtp', 'smtp_host' => 'ssl://smtp.googlemail.com', 'smtp_port' => 465, 'smtp_user' => '[email protected]', 'smtp_pass' =>'password', ); $this->load->library('email', $config); $this->email->set_newline("\r\n"); $this->email->from('[email protected]', 'Jerry'); $this->email->to('[email protected]'); $this->email->subject('this is an email test'); $this->email->message('this is test message!'); if($this->email->send()) { echo 'Your email was sent'; } else { show_error($this->email->print_debugger()); } } ...

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  • Python: Calling method A from class A within class B?

    - by Tommo
    There are a number of questions that are similar to this, but none of the answers hits the spot - so please bear with me. I am trying my hardest to learn OOP using Python, but i keep running into errors (like this one) which just make me think this is all pointless and it would be easier to just use methods. Here is my code: class TheGUI(wx.Frame): def __init__(self, title, size): wx.Frame.__init__(self, None, 1, title, size=size) # The GUI is made ... textbox.TextCtrl(panel1, 1, pos=(67,7), size=(150, 20)) button1.Bind(wx.EVT_BUTTON, self.button1Click) self.Show(True) def button1Click(self, event): #It needs to do the LoadThread function! class WebParser: def LoadThread(self, thread_id): #It needs to get the contents of textbox! TheGUI = TheGUI("Text RPG", (500,500)) TheParser = WebParser TheApp.MainLoop() So the problem i am having is that the GUI class needs to use a function that is in the WebParser class, and the WebParser class needs to get text from a textbox that exists in the GUI class. I know i could do this by passing the objects around as parameters, but that seems utterly pointless, there must be a more logical way to do this that doesn't using classes seem so pointless? Thanks in advance!

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