The purpose of Protocols in Clojure is to solve the Expression Problem in an efficient manner. So, what’s the Expression Problem? It refers to the basic problem of extensibility: our programs manipulate data types using operations. As our programs evolve, we need to extend them with new data types and new operations. And particularly, we … Read more
This will work on 10px or px10 (defn parse-int [s] (Integer. (re-find #”\d+” s ))) it will parse the first continuous digit only so user=> (parse-int “10not123”) 10 user=> (parse-int “abc10def11”) 10
I like your reduce version just fine. I think it’s idiomatic. Here’s a version using list comprehension anyways. (defn foo [m f] (into {} (for [[k v] m] [k (f v)])))
Franz, Inc. provides an inexhaustive list of success stories on their website. However: Please don’t assume Lisp is only useful for Animation and Graphics, AI, Bioinformatics, B2B and E-Commerce, Data Mining, EDA/Semiconductor applications, Expert Systems, Finance, Intelligent Agents, Knowledge Management, Mechanical CAD, Modeling and Simulation, Natural Language, Optimization, Research, Risk Analysis, Scheduling, Telecom, and Web … Read more
Matt’s explanation is perfectly fine — and he takes a shot at a comparison to C and Java, which I won’t do — but for some reason I really enjoy discussing this very topic once in a while, so — here’s my shot at an answer. On points (3) and (4): Points (3) and (4) … Read more
I will humbly suggest Seesaw. Here’s a REPL-based tutorial that assumes no Java or Swing knowledge. Seesaw’s a lot like what @tomjen suggests. Here’s “Hello, World”: (use ‘seesaw.core) (-> (frame :title “Hello” :content “Hello, Seesaw” :on-close :exit) pack! show!) and here’s @Abhijith and @dsm’s example, translated pretty literally: (ns seesaw-test.core (:use seesaw.core)) (defn handler [event] … Read more
Once again, it seems I’ve answered my own question by getting impatient and asking it in #clojure on Freenode. Good thing answering your own questions is encouraged on Stackoverflow.com 😀 I had a quick discussion with Rich Hickey, and here is the gist of it. [12:21] <Raynes> Vectors aren’t seqs, right? [12:21] <rhickey> Raynes: no, … Read more
require loads libs (that aren’t already loaded), use does the same plus it refers to their namespaces with clojure.core/refer (so you also get the possibility of using :exclude etc like with clojure.core/refer). Both are recommended for use in ns rather than directly.
Assuming we’re only doing text files here and not some crazy binary stuff. Number 1: how to read an entire file into memory. (slurp “/tmp/test.txt”) Not recommended when it is a really big file. Number 2: how to read a file line by line. (use ‘clojure.java.io) (with-open [rdr (reader “/tmp/test.txt”)] (doseq [line (line-seq rdr)] (println … Read more
Update: Since this answer was posted, some of the tools available have changed. After the original answer, there is an update including information on how to build the example with current tools. It isn’t quite as simple as compiling to a jar and calling the internal methods. There do seem to be a few tricks … Read more