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Search found 365 results on 15 pages for 'clojure'.

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  • Overriding 'require' in Clojure?

    - by StackedCrooked
    Would it be possible to override the 'require' command so that it will try to download a certain resource if it was not found on the local machine. For example: (require 'examples.introduction) ; if not found => download from the net ; (url: http://media.pragprog.com/titles/shcloj/code/examples/introduction.clj)

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  • How to filter a persistent map in Clojure?

    - by Checkers
    I have a persistent map which I want to filter. Something like this: (filter #(-> % val (= 1)) {:a 1 :b 1 :c 2}) The above comes out as ([:a 1] [:b 1]) (a lazy sequence of map entries). However I want to be get {:a 1 :b 1}. How can I filter a map so it remains a map without having to rebuild it from a sequence of map entries?

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  • Clojure: find repetition

    - by demi
    Let we have a list of integers: 1, 2, 5, 13, 6, 5, 7 and I want to find the first number has a duplicate before it and return a vector of two indices, In my sample, it's 5 at [2, 5]. What I did so far is loop, but can I do it more elegant, short way? (defn get-cycle [xs] (loop [[x & xs_rest] xs, indices {}, i 0] (if (nil? x) [0 i] ; Sequence is over before we found a duplicate. (if-let [x_index (indices x)] [x_index i] (recur xs_rest (assoc indices x i) (inc i)))))) No need to return number itself, because I can get it by index and, second, it may be not always there.

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  • Learning Clojure - What should I know about Java and more.

    - by kartan
    Hello, I have started learning Clojure recently, my main programming language is Ruby and I have no Java experience whatsoever. Which Java standard classes are a must to know when working with Clojure? Obviously Clojure doesn't come with a wrapper for everything and a lot of functionality is provided by Java's libraries. There's like a gazillion of them on javadocs - which ones should I explore? Where do I look for and how do I install third party libraries? In Ruby I'd visit Rubyforge or Rubytoolbox and then just gem install the package I found interesting. Which editor/ide for Clojure would you recommend (with the lowest learning curve)? I am trying to use Netbeans with Enclojure and paradoxally it's my biggest obstacle so far: Each generated project has some xml files, folders, library dependencies etc. the purpose of I have no clue. I am doing some labrepl exercises and wanted to try out some of the bundled libraries separately in a new project, but this simple task I cannot accomplish :/ Are there any clojure community driven blogs with news, code tips etc?

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  • SOCharts: Charts by Tags

    - by abhin4v
    Screenshot I created this small app as a weekend hack. It shows the reputations, upvotes, downvotes and accepted answers for a user against the tags for the answers. About I wanted to know how may upvotes I was away from getting the bronze badge for the clojure tag. But I could not find any straightforward way of doing that. So I wrote this app (in Clojure, of course). The SO API is used for the data and the charts are created using the Google Chart API. The charts are opened in the default browser. License Licensed under EPL 1.0. Download If you have Clojure and Leiningen installed, you can simply get the code from https://gist.github.com/725331, save it as socharts.clj and then run lein repl -e "(load \"socharts\")(refer 'socharts.socharts)(-main)" for launching the Swing UI If you don't have Clojure installed, but have Java then download the standalone jar from http://dl.dropbox.com/u/5247/socharts-1.0.0-standalone.jar and run it as javaw -jar socharts-1.0.0-standalone.jar Once the UI is launched, just type your user id in the input box and press <ENTER>. It will take some time to download the data from the SO API (the progress bar shows the download progress) and then it will open the charts in your default browser. You can also run it as a command line app by running lein repl -e "(load \"socharts\")(refer 'socharts.socharts)(-main <userid>)" or java -jar socharts-1.0.0-standalone.jar <userid> where you replace <userid> with your user id. Be warned that because of a missing feature in the SO API, it will fetch the data for each question you have answered. So the maximum limit is 10000 answers (the SO API call limit). Platform All platforms with Java 1.6. Contact You can reach me at abhinav [at] abhinavsarkar [dot] net. Please report bugs/comments/suggestions as answers to this post. Code Code was written in Clojure with the UI in Swing. It is available at https://gist.github.com/725331. It's a public gist so your can fork it if you like to do some changes.

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  • C# Dev - I've tried Lisps, but I don't get it.

    - by Jonathan Mitchem
    After a few months of learning about and playing with lisps, both CL and a bit of Clojure, I'm still not seeing a compelling reason to write anything in it instead of C#. I would really like some compelling reasons, or for someone to point out that I'm missing something really big. The strengths of a Lisp (per my research): Compact, expressive notation - More so than C#, yes... but I seem to be able to express those ideas in C# too. Implicit support for functional programming - C# with LINQ extension methods: mapcar = .Select( lambda ) mapcan = .Select( lambda ).Aggregate( (a,b) = a.Union(b) ) car/first = .First() cdr/rest = .Skip(1) .... etc. Lambda and higher-order function support - C# has this, and the syntax is arguably simpler: "(lambda (x) ( body ))" versus "x = ( body )" "#(" with "%", "%1", "%2" is nice in Clojure Method dispatch separated from the objects - C# has this through extension methods Multimethod dispatch - C# does not have this natively, but I could implement it as a function call in a few hours Code is Data (and Macros) - Maybe I haven't "gotten" macros, but I haven't seen a single example where the idea of a macro couldn't be implemented as a function; it doesn't change the "language", but I'm not sure that's a strength DSLs - Can only do it through function composition... but it works Untyped "exploratory" programming - for structs/classes, C#'s autoproperties and "object" work quite well, and you can easily escalate into stronger typing as you go along Runs on non-Windows hardware - Yeah, so? Outside of college, I've only known one person who doesn't run Windows at home, or at least a VM of Windows on *nix/Mac. (Then again, maybe this is more important than I thought and I've just been brainwashed...) The REPL for bottom-up design - Ok, I admit this is really really nice, and I miss it in C#. Things I'm missing in a Lisp (due to a mix of C#, .NET, Visual Studio, Resharper): Namespaces. Even with static methods, I like to tie them to a "class" to categorize their context (Clojure seems to have this, CL doesn't seem to.) Great compile and design-time support the type system allows me to determine "correctness" of the datastructures I pass around anything misspelled is underlined realtime; I don't have to wait until runtime to know code improvements (such as using an FP approach instead of an imperative one) are autosuggested GUI development tools: WinForms and WPF (I know Clojure has access to the Java GUI libraries, but they're entirely foreign to me.) GUI Debugging tools: breakpoints, step-in, step-over, value inspectors (text, xml, custom), watches, debug-by-thread, conditional breakpoints, call-stack window with the ability to jump to the code at any level in the stack (To be fair, my stint with Emacs+Slime seemed to provide some of this, but I'm partial to the VS GUI-driven approach) I really like the hype surrounding Lisps and I gave it a chance. But is there anything I can do in a Lisp that I can't do as well in C#? It might be a bit more verbose in C#, but I also have autocomplete. What am I missing? Why should I use Clojure/CL?

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  • What is a dotted pair's analogy in other Lisp implementations?

    - by octopusgrabbus
    What is Scheme's dotted pair construct analogous to in other Lisp implementations? I can make a vector or list quite easily, and understand those in Clojure, even though the syntax is a little different, like Clojure's vectors use square brackets []. However, seeing a dotted pair for the first time threw me. It almost looks like it is an implementation of of map. I'm not looking for a discussion, but more for use or the dotted pair equivalent in other Lisp dialects, like Clojure, or even Python. Thanks.

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  • How do I call overloaded Java methods in Clojure.

    - by Pat Wallace
    For this example Java class: package foo; public class TestInterop { public String test(int i) { return "Test(int)"; } public String test(Object i) { return "Test(Object)"; } } When I start Clojure and try to call the test(int) method, the test(Object) method is called instead, because Clojure automatically boxes the integer into a java.lang.Integer object. How do I force Clojure to call the test(int) method? user=> (.test (new foo.TestInterop) 10) "Test(Object)" I want to call methods like Component.add(Component comp, int index) in AWT, but instead keep calling add(Component comp, Object constraints), so the buttons on my toolbar always appear in the wrong order.

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  • Write this java source in Clojure

    - by tikky
    Need to write this code in clojure.... package com.example.testvaadin; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import clojure.lang.RT; import com.vaadin.Application; import com.vaadin.terminal.gwt.server.AbstractApplicationServlet; public class Clojure4Vaadin extends AbstractApplicationServlet { @Override protected Class getApplicationClass()throws ClassNotFoundException { return Application.class; } @Override protected Application getNewApplication(HttpServletRequest request) throws ServletException { try { RT.load(getServletConfig().getInitParameter("script-name"), true); return (Application)RT.var(getServletConfig().getInitParameter("package-name"),getServletConfig().getInitParameter("function-name")).invoke(new String[0]); } catch (Exception e) { throw new ServletException(e); } } }

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  • How do I get the set of all letters in Java/Clojure?

    - by Jason Baker
    In Python, I can do this: >>> import string >>> string.letters 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' Is there any way to do something similar in Clojure (apart from copying and pasting the above characters somewhere)? I looked through both the Clojure standard library and the java standard library and couldn't find it.

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  • Is there possible in clojure to make a deadlock (or anything bad case) using agents?

    - by hsestupin
    CLojure agents is powerful tool. So actions to the agents are asynchronously sent using functions "send" and "send-off". And in theory there couldn't appear something like deadlock. Is there possible to write some clojure code (for example invoking from some action another action to another agent) using agents in which we have some concurrency problem - it could be deadlock, race condition or anything else. (guys, i'm very sorry for my english)

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  • Map entries become vectors when piped thru a macro

    - by Gavin Grover
    In Clojure, a map entry created within a macro is preserved... (class (eval `(new clojure.lang.MapEntry :a 7))) ;=> clojure.lang.MapEntry ...but when piped thru from the outside context collapses to a vector... (class (eval `~(new clojure.lang.MapEntry :a 7))) ;=> clojure.lang.PersistentVector This behavior is defined inside LispReader.syntaxQuote(Object form) condition if(form instanceof IPersistentCollection). Does anyone know if this is intended behavior or something that will be fixed?

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  • How to implement lambda as a function called "lambda" in Clojure?

    - by dirtyvagabond
    I'd like to be able to define lambdas using common Lisp syntax, in Clojure. For example: (lambda (myarg) (some-functions-that-refer-to myarg)) This needs to result in the same as: #(some-functions-that-refer-to %) In my case, I know I'll always have exactly one arg, so perhaps that simplifies things. (But it can be called anything -- "myarg" or whatever.) I suspect a workable solution is to "(defmacro lambda ...". If so, I'm not sure of the best way to proceed. How to cleanly translate the arg name to %? And how to end up with the correct function? Or, is there a simpler solution than writing my own macro that actually re-implements Clojure's... lambda?

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  • When and how should custom hierarchies be used in clojure?

    - by Rob Lachlan
    Clojure's system for creating an ad hoc hierarchy of keywords is familiar to most people who have spent a bit of time with the language. For example, most demos and presentations of the language include examples such as (derive ::child ::parent) and they go on to show how this can be used for multi-method dispatch. In all of the slides and presentations that I've seen, they use the global hierarchy. But it is possible to keyword relationships in custom hierarchies. Some questions, therefore: Are there any guidelines on when this is useful or necessary? Are there any functions for manipulating hierarchies? Merging is particularly useful, so I do this: (defn merge-h [& hierarchies] (apply merge-with (cons #(merge-with clojure.set/union %1 %2) hierarchies)) But I was wondering if such functions already exist somewhere.

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  • Using slime's C-x C-e (Eval the form under the point) with swank-clojure in emacs

    - by hiheelhottie
    Hi, I'm using swank-clojure in emacs on OSX. I'm able to run a slime session. When I use C-x C-e on a simple form in a .clj file like (+ 7 7) I get an sldb buffer with Unable to resolve symbol: + in this context [Thrown class java.lang.Exception] I'm able to evaluate that form in the slime session directly. I was hoping the form in the clj file would get evaluated in the running slime session. Can someone explain how C-x C-e works in swank-clojure and how I can get the form to be evaluated in the running slime session? Thanks, hhh

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  • How do I get the sequence of numbers in a sorted-set that are between two integers in clojure?

    - by Greg Rogers
    Say I have a sorted-set of integers, xs, and I want to retrieve all the integers in xs that are [x, y), ie. between x and y. I can do: (select #(and (>= % x) (< % y)) xs) But this is inefficient - O(n) when it could be O(k log n) where k is the number of integers returned. I am just learning clojure so here is how I would do it in C++: set<int>::iterator first = xs.lower_bound(x); set<int>::iterator last = xs.upper_bound(y); for (; first != last; ++first) // do something with *first Can I do this in clojure?

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  • How do I get the sequence of numbers in a sorted-set that are between two integers in clojure?

    - by Greg Rogers
    Say I have a sorted-set of integers, xs, and I want to retrieve all the integers in xs that are [x, y), ie. between x and y. I can do: (select #(and (>= % x) (< % y)) xs) But this is inefficient - O(n) when it could be O(log n), I expect the number of elements returned to be small. Using take-while and drop-while would let me exit once I've reached y, but I still can't jump to x efficiently. I am just learning clojure so here is how I would do it in C++: set<int>::iterator first = xs.lower_bound(x); set<int>::iterator last = xs.lower_bound(y); for (; first != last; ++first) // do something with *first Can I do this in clojure?

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