Thoughts on architecture components and software stability. In this article we also discuss one approach to evaluating architecture quality. Software Architecture is about drawing boxes and arrows. – Some architect Architecture Quality Challenge Evaluating software architecture is difficult. Unlike ...

Emacs is great for editing text, IntelliJ IDEA is great for navigation. Let’s take best from both worlds into one editor. Rationale If you can configure it, you will configure it - Anonymous, about Linux Emacs is keyboard-driven editor, meaning all actions you can do without mouse or touchpad. It is...

Evolville is an imaginary computer world, inhabited by creatures. They live, move, eat, communicate and evolve. .bordered { border: 1px solid grey; } In previous post we’ve seen the origins of the World. It looks pretty simple: white space inhabited by some creatures. All those creatures just moving...

Evolville is an imaginary computer world, inhabited by creatures. They live, move, eat, communicate and evolve. This is going to be series of posts for simulation, starting from scratch and test various evolution strategies. Our world will evolve, our creatures will evolve, our code will evolve. Wel...

Implementing Depth-First Search for the Binary Tree without stack and recursion. Binary Tree Array This is binary tree. 0 is a root node. 0 has two children: left 1 and right: 2. Each of its children have their children and so on. The nodes without children are leaf nodes (3,4,5,6). The number of ed...

Find the value of d < 1000 for which 1/d contains the longest recurring cycle in its decimal fraction part. Permalink: https://projecteuler.net/problem=26 1/2 = 0.5 1/3 = 0.(3) 1/4 = 0.25 1/5 = 0.2 1/6 = 0.1(6) 1/7 = 0.(142857) 1/8 = 0.125 1/9 = 0.(1) 1/10 = 0.1 As you see for d from 2 to 10, the lo...

Let’s celebrate geeky New Year by drawing New Year Tree using Clojure! Problem Write a program which prints New Year Tree to console. Source code should take as small number of characters as possible. I came up with the following tree rules: Star. There is should be a star on top of the tree. Triang...

Quick overview of the classic Design Patterns in Clojure Disclaimer: Most patterns are easy to implement because we use dynamic typing, functional programming and, of course, Clojure. Some of them look wrong and ugly. It’s okay. All characters are fake, coincidences are accidental. Index Intro Episo...

Cook, little pot, cook! – The Magic Porridge Pot, Brothers Grimm I’ve just released littlepot, tiny library devoted to transform batched request into single element request. The Problem Imagine you develop a service which return one random image and some witty text below. As an image provider, you h...

Apache Spark is a fast and general engine for large-scale data processing. 100 times faster than Hadoop. Everyone knows SQL. But traditional databases are not good in hadling big amount of data. Nevertheless, SQL is a good DSL for data processing and it is much easier to understand Spark if you have...

Emacs org-mode use cases, for non-programmers. org-mode Org-mode is what makes emacs popular among non-programmers community. It could replace your Notes, TODO, Calendar, Agenda, Project Management, Time Tracking, Spreadsheets and other apps. But seems like most of org-mode tutorials are dedicated t...

Let’s celebrate Pi day in clojure! Tweet Exactly 140 characters to print 9 digits of $\pi$ (3.141592654) (let[r reduce N(rest(range))t take](clojure.pprint/cl-format nil"~11f" (r +' -2(map #(/(r *' 2(t % N))(r *'(t %(take-nth 2 N))))(t 99 N)))9)) “Sugared” version There are two parts of a problem: C...

Pouring a bit light on SecurityManager and its use cases. Intro You can do a terrible things in java using sun.misc.Unsafe class. Some really creepy examples were discussed in Java Magic. Part 5: sun.misc.Unsafe SecurityManager is a guard, which could help to prevent some sensitive actions (io, net,...

Clojure Cup 2014 has finished and we’ve build clojure app in two days! We are proud to announce funstructor (pre-alpha) Funstructor Funstructor is a turn-based multiplayer card game for clojurists. Your goal is to make some clojure code snippet, function or expression, but instead of typing characte...

What is the first term in the Fibonacci sequence to contain 1000 digits? Permalink: https://projecteuler.net/problem=25 We’ve introduced Fibonacci sequence at Clojure Euler: Problem 002 Lazy sequence generates fibonacci numbers is dead simple: (defn fibonacci [] (->> [0 1] (iterate (fn [[a b]] [b (+...

A permutation is an ordered arrangement of objects. For example, 3124 is one possible permutation of the digits 1, 2, 3 and 4. If all of the permutations are listed numerically or alphabetically, we call it lexicographic order. The lexicographic permutations of 0, 1 and 2 are: 012 021 102 120 201 21...

Recently, I’ve re-read awesome java book Effective Java by Joshua Bloch. The book contains 78 independent items, discussing various aspects of programming in java. Something like mini-design patterns with emphasis on their pros and cons. Few notes from each item as a refresher. Item 1: Consider stat...

Programming Sucks. 1. Programming Sucks …many of the programs you depend on are written by dicks and idiots Funny ranting about crazy programming life. Every programmer occasionally, when nobody’s home, turns off the lights, pours a glass of scotch, puts on some light German electronica, and opens u...

Clojure is a great language, and as every language, it has some unobvious and strange things, which seem confusing. Some of such things are gathered here. Most of them encountered by stupidity, docs misunderstanding, clojure specifics and procrastination. 1. Anybody home? (contains? [10 20 30] 20) =...

Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers. Permalink: http://projecteuler.net/problem=23 To define abundant number let’s revisit sum-of-proper-divisors from the Clojure Euler: Problem 021 (defn sum-of-proper-divisors [n] (let [base (filter #...

Numberto has new features! In previous post I wrote about simple clojure library numberto for experiments with numbers. New version of numberto has a bunch of new features. Expressions Expressions package provides two functions: eval-infix to evaluate infix expression and infix->prefix to build pref...

How to live in the Kingdom of Nouns, why mathematicians cry, filling gaps in algorithms, portion of clojure, STM, HTTP and more. 1. Execution in the Kingdom of Nouns Another great Steve Yegge’s post. Not a post, a tale about Javaland, a place where all verbs are owned by nouns. Accept it like an ana...

Using names.txt a 46K text file containing over five-thousand first names, begin by sorting it into alphabetical order. Then working out the alphabetical value for each name, multiply this value by its alphabetical position in the list to obtain a name score. For example, when the list is sorted int...

Evaluate the sum of all the amicable numbers under 10000. Permalink: http://projecteuler.net/problem=21 Let d(n) be defined as the sum of proper divisors of n (numbers less than n which divide evenly into n). If d(a) = b and d(b) = a, where a != b, then a and b are an amicable pair and each of a and...

All you need to play with numbers! numberto simple clojure library with a bunch of functions operating on numbers. I created this project for two reasons: Solving problems on Project Euler, 4Clojure and just playground with numbers needed common functions. I just extracted them to separate util libr...

Brainfuck Interpreter in two tweets. Previous article Code Golf: Game of Life raised some interest, and I decided to proceed. Today’s problem is a Brainfuck Interpreter. Brainfuck is an esoteric programming language, famous because of its small command set. It is based on array of cells (Turing Tape...

Why your software sucks and what is the “Secret Weapon”. Also, algorithm complexities refresher, functional programming, including Scala and Clojure, concurrency and lot of humor. 1. Big Ball of Mud What does your programming day look like? The article describes problems in software design and expla...

Find the sum of the digits in the number 100! Permalink: http://projecteuler.net/problem=20 First of all we need to calculate factorial. Without integer overflows, stack overflows and other caveats. Previous article Fast Factorial has working solution that we might use. (defn ! [n] (reduce *' (range...

How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)? Permalink: http://projecteuler.net/problem=19 Project Euler also gives following information: 1 Jan 1900 was a Monday. A poem Thirty days has September, April, June and November. All the rest ha...

randomorg-0.1 released! If you use random numbers in your software you might be interested in better numbers distribution than Random.nextInt(). Someone solves this problem with hardware generators, few entropy sources and even books. By the way, there is great service random.org which allows to gen...