j-cr

Since it has come up a few times, I thought I’d write up some of the basic ideas around domain modeling in Clojure, and how they relate to keyword names and Specs. Firmly grasping these concepts will help us all write code that is simpler, cleaner, and easier to understand.

Clojure is a data-oriented language: we’re all familiar with maps, vectors, sets, keywords, etc. However, while data is good, not all data is equally good. It’s still possible to write “bad” data in Clojure.

“Good” data is well defined and easy to read; there is never any ambiguity about what a given data structure represents. Messy data has inconsistent structure, and overloaded keys that can mean different things in different contexts. Good data represents domain entities and a logical model; bad data represents whatever was convenient for the programmer at a given moment. Good data stands on its own, and can be reasoned about without any other knowledge of the codebase; bad data is deeply and tightly coupled to specific generating and

How Clojure's documentation can leapfrog other languages

Summary

I made a documentation generator that cashes in on Clojure's dynamism. See the play-cljs docs (a ClojureScript game library) for an example of its output.

The Problem

Like many of you, I've often wondered what my final regret will be on my deathbed. My best guess came to me in a dream recently. I was walking across the charred earth of an apocalyptic future world, maneuvering around the remains of the less fortunate. I was startled to find a young girl, barely holding onto her life. She murmured something to me. I asked her to repeat it, and she said more loudly: "I...wish your Clojure projects didn't have such crappy documentation."

Rich Already Answered That!

A list of commonly asked questions, design decisions, reasons why Clojure is the way it is as they were answered directly by Rich (even when from many years ago, those answers are pretty much valid today!). Feel free to point friends and colleagues here next time they ask (again). Answers are pasted verbatim (I've made small adjustments for readibility, but never changed a sentence) from mailing lists, articles, chats.

How to use:

The link in the table of content jumps at the copy of the answer on this page.
The link on the answer itself points back at the original post.

Table of Content

HTML search and replace in Clojure

In Clojure, data structures are mostly built from a handful of core data structures such as lists, vectors, maps, and sets. This means that most data structures can leverage all of the generic data transformation and querying functions built for the core data structures instead of having to rebuild the same functionality for each data structure. This feature in combination with Clojure's rich standard library makes Clojure very attractive for solving data munching problems from other domains.

In this article, I'm going to demonstrate these capabilities for solving HTML transformations using Clojure. First, I'm going to describe how HTML can be represented in Clojure. With this representation in mind, I'll demonstrate how we can transform HTML documents in Clojure. Finally, I'll tie the transformations together with the HTML parsing and formatting to produce a complete solution.

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

A Russian translation of this article can be found here, contributed by Timur Demin.
A Turkish translation can be found here, contributed by agyild.
There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

ABOUT

about:config settings to harden the Firefox browser. Privacy and performance enhancements.
To change these settings type 'about:config' in the url bar. Then search the setting you would like to change and modify the value. Some settings may break certain websites from functioning and rendering normally. Some settings may also make firefox unstable. I am not liable for any damages/loss of data.

Not all these changes are necessary and will be dependent upon your usage and hardware. Do some research on settings if you don't understand what they do. These settings are best combined with your standard privacy extensions (~~HTTPS Everywhere~~ No longer required: Enable HTTPS-Only Mode, NoScript/Request Policy, uBlock origin, agent spoofing, ~~Privacy Badger~~ etc), and all plugins set to "Ask To Activate".

	(defn extrapolate*
	[gen-next shrink v]
	(lazy-seq
	(let [next-item (gen-next v)
	new-v (shrink (conj v next-item))]
	(cons next-item
	(extrapolate* gen-next shrink new-v)))))

	(defn extrapolate
	"Returns a lazy seq produced by extrapolating `coll` with given rules.

	;; see http://stackoverflow.com/questions/14724991/modelling-multiple-many-to-many-relationships-in-datomic

	(require '[datomic.api :as d])
	(def uri "datomic:mem://test")
	(d/create-database uri)
	(def conn (d/connect uri))

	(d/transact conn [ ;; User
	{:db/id #db/id [:db.part/db]
	:db/ident :user/username

	;;; late-night-theme.el --- Late Night theme for Emacs 24

	;; Author: Alex Schroeder
	;; Maintainer: Daehyub Kim <lateau at gmail.com>
	;; URL: https://gist.github.com/4420862
	;; Version: 0.0
	;; Keywords: theme, color

	;;; Commentary:

	;; Big thanks to Christophe Grand - https://groups.google.com/d/msg/clojure/L1GiqSyQVVg/m-WJogaqU8sJ
	(defprotocol ReversibleMap
	(rmap [m]))

	(defn- rdissoc [d r v]
	(if-let [[_ k] (find r v)] (dissoc d k) d))

	(deftype Bimap [^clojure.lang.IPersistentMap direct reverse]
	Object
	(hashCode [x]