clojure

问题 I have a trivial lein project where -main contains a future: (def f (future 42)) (defn -main [& args] (println @f)) When I run lein run it prints 42 but does not return. I don't understand why it does not return ? How do I get lein run to return ? 回答1: Your question is really twofold: Why does lein not return? lein hangs because the thread pool which backs Clojure futures does not use daemon threads so you have to explicitly shut it down. If you change your code to the following, it should

问题 I have a trivial lein project where -main contains a future: (def f (future 42)) (defn -main [& args] (println @f)) When I run lein run it prints 42 but does not return. I don't understand why it does not return ? How do I get lein run to return ? 回答1: Your question is really twofold: Why does lein not return? lein hangs because the thread pool which backs Clojure futures does not use daemon threads so you have to explicitly shut it down. If you change your code to the following, it should

问题 How can you filter text nodes in XML with Clojure zippers? For example, you may have a pretty-printed XML document that interleaves element nodes with text nodes containing whitespace: (def doc "<?xml version=\"1.0\"?> <root> <a>1</a> <b>2</b> </root>") If you want to retrieve the content of the root 's children, you can do this: (require '[clojure.data.xml :as xml] '[clojure.zip :as zip] '[clojure.data.zip :as zf] '[clojure.data.zip.xml :as zip-xml]) (-> doc xml/parse-str zip/xml-zip (zip

问题 I followed this very helpful guide on getting this development environment set up. When running the emacs.bat I get the following error in Emacs: File error: Cannot open load file, clojure-auto Unfortunitely I am completely new to both Clojure and Emacs, so any help in even figuring out where to begin looking would be helpful. Also, as a side note the last step in the guide is: Start up Emacs using the emacs.bat file. Then, just type "M-x slime", and the REPL will come up, and you're on your

问题 I have two macros. The first one takes a symbol as the only parameter (because it's passed to def, which needs a symbol). The second function takes a list of symbols and should call the first with each symbol individually. (defmacro m1 [s] '(let [f# ... dynamic function definition ...] (def ~s f#)) The second macro should take a list of symbols and pass them to the first, but I can't get it to work. The best I could come up with was the following: (defmacro m2 [symbols] `(for [s# ~symbols]

问题 I have two macros. The first one takes a symbol as the only parameter (because it's passed to def, which needs a symbol). The second function takes a list of symbols and should call the first with each symbol individually. (defmacro m1 [s] '(let [f# ... dynamic function definition ...] (def ~s f#)) The second macro should take a list of symbols and pass them to the first, but I can't get it to work. The best I could come up with was the following: (defmacro m2 [symbols] `(for [s# ~symbols]

问题 Lets say I have (def test-left [{:name "Sean" :age 27} {:name "Ross" :age 27} {:name "Brian" :age 22}]) and (def test-right [{:owner "Sean" :item "Beer"} {:owner "Sean" :item "Pizza"} {:owner "Ross" :item "Computer"} {:owner "Matt" :item "Bike"}]) When I do a (clojure.set/join test-left test-right) I get a Cartesian product. 12 rows. What I want is Inner-join on :name of left = :owner of right so that I get only those result which have matching rows in the right side So I get [{:name "Sean"

问题 I'm a Clojure noob, so bear with me. I'm trying to write a simple program to send a command through a socket and get a response. My code is: (def IPaddress "10.71.18.81") (def port 1500) (def socket (new Socket IPaddress port)) (print (clojure.string/join ["\nConnected to HSM: " (. socket isConnected)])) (def in (DataInputStream. (BufferedInputStream. (. socket getInputStream)))) (def out (DataOutputStream. (BufferedOutputStream. (. socket getOutputStream)))) (def command "Some string") (.

问题 Meikel Brandmeyer wrote a post on dispatch in Clojure with the URL title Static vs Dynamic. He writes: Protocols are not the only place where we have a trade-off of static vs. dynamic. There are several places where such a trade-off can be spotted. He provides the following example of static dispatch in a protocol: (defprotocol Flipable (flip [thing])) (defrecord Left [x]) (defrecord Right [x]) (extend-protocol Flipable Left (flip [this] (Right. (:x this))) Right (flip [this] (Left. (:x this)

问题 I'm experimenting with clojure and am trying to get a feel for using 3rd party libraries. I've been able to download some source, bundle it into a jar file with leiningen, put it in my classpath and (use 'lib.etc) in my script. I've also played around with the objects in java.lang.*. I haven't had any success with 3rd party java, though. $ java -cp clojure.jar:clojure-contrib.jar:com.jcraft.jsch_0.1.31.jar clojure.main Clojure 1.1.0 user=> (require 'com.jcraft.jsch) java.io