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  • List of Lua derived VMs and Languages

    - by Shane Holloway
    Is there a compendium of virtual machines and languages derived or inspired by Lua? By derived, I mean usage beyond embedding and extending with modules. I'm wanting to research the Lua technology tree, and am looking for our combined knowledge of what already exists. Current List: Bright - A C-like Lua Derivative http://bluedino.net/luapix/Bright.pdf Agena - An Algol68/SQL like Lua Derivative http://agena.sourceforge.net/ LuaJIT - A (very impressive) JIT for Lua http://luajit.org MetaLua - An ML-style language extension http://metalua.luaforge.net/

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  • Derivative of a Higher-Order Function

    - by Claudiu
    This is in the context of Automatic Differentiation - what would such a system do with a function like map, or filter - or even one of the SKI Combinators? Example: I have the following function: def func(x): return sum(map(lambda a: a**x, range(20))) What would its derivative be? What will an AD system yield as a result? (This function is well-defined on real-number inputs).

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  • Tracking the user function that threw the exception

    - by makerofthings7
    I've been given a large application with only one try..catch at the outer most level. This application also throws exceptions all the time, and is poorly documented. Is there any pattern I can implement that will tell me what user method is being called, the exception being thrown, and also the count of exceptions? I'm thinking of using a dictionary with reflection to get the needed information, but I'm not sure if this will work. What do you think?

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  • [Perl] Testing for EAGAIN / EWOULDBLOCK on a recv

    - by Robert S. Barnes
    I'm testing a socket to see if it's still open: my $dummy = ''; my $ret = recv($sock, $dummy, 1, MSG_DONTWAIT | MSG_PEEK); if (!defined $ret || (length($dummy) == 0 && $! != EAGAIN && $! != EWOULDBLOCK )) { logerr("Broken pipe? ".__LINE__." $!"); } else { # socket still connected, reuse logerr(__LINE__.": $!"); return $sock; } I'm passing this code a socket I know for certain is open and it's always going through the first branch and logging "Broken pipe? 149 Resource temporarily unavailable". I don't understand how this is happening since "Resource temporarily unavailable" is supposed to correspond to EAGAIN as far as I know. I'm sure there must be something simple I'm missing. And yes, I know this is not a full proof way to test and I account for that.

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  • How to determine if an application is using the GPU

    - by Andrew
    I'm looking for a way to determine how to know whether an application is using the GPU with Objective-C. I want to be able to determine if any applications currently running on the system have work going on on the GPU (ie: a reason why the latest MacBook Pros would switch to the discrete graphics over the Intel HD graphics). I've tried getting the information by crossing the list of active windows with the list of windows that have their backing location stored in video memory using Quartz Window Services, but all that does is return the Dock application and I have other applications open that I know are using the GPU (Photoshop CS5, Interface Builder), that and the Dock doesn't require the 330m.

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  • Best way to learn how to use FPGAs

    - by Myrrdyn
    In next weeks probably I will have some little FPGA to play with. I have a programmer background (C, C++, Java mostly) and some (very) limited experience in electronics. What are the best tools to know if you want to develop on FPGAs? What are the best languages to study? (what HW description languages?) Have you some examples of little "toy projects" that can be interesting, easy, and "eye-opener"? Thanks in advance. Edit: More details: if I understood correctly, the device I will be playing on will have an ARM core (no idea which one) and a 300k gates FPGA I'm looking specifically at some Linux free sw / open source tools...

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  • how/resources to compile a procedural language into [sql]

    - by Philip
    I am looking into the possibility/feasibility/resources for building a cross compiler which takes a procedural or Object Oriented language like C, or Java and compiling it into SQL. I understand that the advantage of SQL code is performing set operations which is fundamentally different from procedural languages which generally process 1 at a time. If anyone has done this before, or if it is thought of as too complicated to do or any other ideas/concerns/suggestions would be greatly appreciated. Thanks in advance Philip

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  • Microsoft Solver Foundation constraint

    - by emaster70
    Hello, I'm trying to use Microsoft Solver Foundation 2 to solve a fairly complicated situation, however I'm stuck with an UnsupportedModelException even when I dumb down the model as much as possible. Does anyone have an idea of what I'm doing wrong? Following is the least example required to reproduce the problematic behavior. var ctx = SolverContext.GetContext(); var model = ctx.CreateModel(); var someConstant = 1337.0; var decisionA = new Decision(Domain.Real, "decisionA"); var decisionB = new Decision(Domain.Real, "decisionB"); var decisionC = new Decision(Domain.Real, "decisionC"); model.AddConstraint("ca", decisionA <= someConstant); model.AddConstraint("cb", decisionB <= someConstant); model.AddConstraint("cc", decisionC <= someConstant); model.AddConstraint("mainConstraint", Model.Equal(Model.Sum(decisionA, decisionB, decisionC), someConstant)) model.AddGoal("myComplicatedGoal", GoalKind.Minimize, decisionC); var solution = ctx.Solve(); solution.GetReport().WriteTo(Console.Out); Console.ReadKey(); Please consider that my actual model should include, once complete, a few constraints in the form of a*a+b*a <= someValue, so if what I'm willing to do ultimately isn't supported, please let me know in advance. If that's the case I'd also appreciate a suggestion of some other solver with a .NET friendly interface that I could use (only well-known commercial packages, please). Thanks in advance

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  • Delphi On Windows

    - by j-t-s
    Hi All I have decided (whether it's for better or for worse), to start learning Delphi. But, Is it available in Visual Studio? Or is there an IDE for it? I googled Delphi, but came up with some really weird sites. Thanks Jason

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  • Multiple Socket Connections

    - by BSchlinker
    I need to write a server which accepts connections from multiple client machines, maintains track of connected clients and sends individual clients data as necessary. Sometimes, all clients may be contacted at once with the same message, other times, it may be one individual client or a group of clients. Since I need confirmation that the clients received the information and don't want to build an ACK structure for a UDP connection, I decided to use a TCP streaming method. However, I've been struggling to understand how to maintain multiple connections and keep them idle. I seem to have three options. Use a fork for each incoming connection to create a separate child process, use pthread_create to create an entire new thread for each process, or use select() to wait on all open socket IDs for a connection. Recommendations as to how to attack this? I've begun working with pthreads but since performance will likely not be an issue, multicore processing is not necessary and perhaps there is a simpler way.

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  • What is the right approach to checksumming UDP packets

    - by mr.b
    I'm building UDP server application in C#. I've come across a packet checksum problem. As you probably know, each packet should carry some simple way of telling receiver if packet data is intact. Now, UDP already has 2-byte checksum as part of header, which is optional, at least in IPv4 world. Alternative method is to have custom checksum as part of data section in each packet, and to verify it on receiver. My question boils down to: is it better to rely on (optional) checksum in UDP packet header, or to make a custom checksum implementation as part of packet data section? Perhaps the right answer depends on circumstances (as usual), so one circumstance here is that, even though code is written and developed in .NET on Windows, it might have to run under platform-independent Mono.NET, so eventual solution should be compatible with other platforms. I believe that custom checksum algorithm would be easily portable, but I'm not so sure about the first one. Any thoughts? Also, shouts about packet checksumming in general are welcome.

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  • What could be the Java successor Oracle wants to invest in?

    - by deamon
    I've read that Oracle wants to invest into another language than Java: "On the other hand, Oracle has been particularly supportive of alternative JVM languages. Adam Messinger ( http://www.linkedin.com/in/adammessinger ) was pretty blunt at the JVM Languages Summit this year about Java the language reaching it's logical end and how Oracle is looking for a 'higher level' language to 'put significant investment into.'" But what language could be the one Oracle wants to invest in? Is there another candidate than Scala?

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  • Make a function which returns the original list except the argument

    - by Alex
    I want make a function which takes a list of string and a string and returns NONE if there is no string in the string list, otherwise it returns SOME of the list of string which is the same as the original list of string except it doesn't contain the initial string (pattern): fun my_function (pattern, source_list) = case source_list of [] => NONE | [x] => if pattern = x then SOME [] else NONE | x::xs => if pattern = x then SOME (xs) else SOME (x) :: my_function (pattern, xs) (* this is wrong, what to do here?*) val a = my_function ("haha", ["12", "aaa", "bbb", "haha", "ccc", "ddd"]) (* should be SOME ["12", "aaa", "bbb", "ccc", "ddd"]*) val a2 = my_function ("haha2", ["123", "aaa", "bbb", "haha", "ccc"]) (*should be NONE*) val a3 = my_function ("haha3", ["haha3"]) (* should be SOME []*) I'm confused by the 3rd case: x::xs => .... What should do there? Note that I'd like not to use any sml library function.

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  • Problem with a blocking network task

    - by user326967
    Hello everyone. I'm new in Java so please forgive any obscene errors that I may make :) I'm developing a program in Java that among other things it should also handle clients that will connect to a server. The server has 3 threads running, and I have created them in the following way : DaemonForUI du; DaemonForPort da; DaemonForCheck dc; da = new DaemonForPort(3); dc = new DaemonForCheck(5); du = new DaemonForUI(7); Thread t_port = new Thread(da); Thread t_check = new Thread(dc); Thread t_ui = new Thread(du); t_port.setName("v1.9--PORTd"); t_check.setName("v1.9-CHECKd"); t_ui.setName("v1.9----UId"); t_port.start(); t_check.start(); t_ui.start(); Each thread handles a different aspect of the complete program. The thread t_ui is responsible to accept asynchronous incoming connections from clients, process the sent data and send other data back to the client. When I remove all the commands from the previous piece of code that has to with the t_ui thread, everything runs ok which in my case means that the other threads are printing their debug messages. If I set the t_ui thread to run too, then the whole program blocks at the "accept" of the t_ui thread. After reading at online manuals I saw that the accepted connections should be non-blocking, therefore use something like that : public ServerSocketChannel ssc = null; ssc = ServerSocketChannel.open(); ssc.socket().bind(new InetSocketAddress(port)); ssc.configureBlocking(false); SocketChannel sc = ssc.accept(); if (sc == null) { ; } else { System.out.println("The server and client are connected!"); System.out.println("Incoming connection from: " + sc.socket().getRemoteSocketAddress()); in = new DataInputStream(new BufferedInputStream(sc.socket().getInputStream())); out = new DataOutputStream(new BufferedOutputStream(sc.socket().getOutputStream())); //other magic things take place after that point... The thread for t_ui is created as follows : class DaemonForUI implements Runnable{ private int cnt; private int rr; public ListenerForUI serverListener; public DaemonForUI(int rr){ cnt = 0; this.rr = rr; serverListener = new ListenerForUI(); } public static String getCurrentTime() { final String DATE_FORMAT_NOW = "yyyy-MM-dd HH:mm:ss"; Calendar cal = Calendar.getInstance(); SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW); return (sdf.format(cal.getTime())); } public void run() { while(true) { System.out.println(Thread.currentThread().getName() + "\t (" + cnt + ")\t (every " + rr + " sec) @ " + getCurrentTime()); try{ Thread.sleep(rr * 1000); cnt++; } catch (InterruptedException e){ e.printStackTrace(); } } } } Obviously, I'm doing something wrong at the creation of the socket or at the use of the thread. Do you know what is causing the problem? Every help would be greatly appreciated.

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