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Clojure Destructuring Tutorial and Cheat Sheet

Simply put, destructuring in Clojure is a way extract values from a datastructure and bind them to symbols, without having to explicitly traverse the datstructure. It allows for elegant and concise Clojure code.

Vectors and Sequences

fireplace

cpr => (require ... :reload)
cpR => (require ... :reload-all)

Evaluation

:Eval (clojure code) => runs (clojure code) in repl
cpp => evaluate inn-most expessions under cursor
cp<movement> => evaluate text described by <movement>
cqp => opens quasi-repl
cqc => quasi-repl command line window

Creating a "DMG installer" for OS X

A DMG Installer is convenient way to provide end-users a simple way to install an application bundle. They are basically a folder with a shortcut to the Applications directory but they can be customized with icons, backgrounds, and layout properties. A DMG file (.dmg) is a Mac OS X Disk Image file and it is used to package files or folders providing compression, encryption, and read-only to the package.

##Creating the DMG file #Disk Utility

Creating a Happy Git Environment on OS X

Step 1: Install Git

brew install git bash-completion

Configure things:

git config --global user.name "Your Name"

git config --global user.email "[email protected]"

	import
	asyncdispatch, asyncnet, htmlparser, xmltree, httpclient, strutils,
	strtabs, streams, uri, sets

	var visited = initSet[string]()

	proc crawl(url: string, client: PAsyncHttpClient = newAsyncHttpClient()) {.async.} =
	if url in visited: return # Already visited this URL.
	echo("Crawling ", url)
	visited.incl(url)

	You can create a new empty branch like this:

	$ git checkout --orphan NEWBRANCH

	--orphan creates a new branch, but it starts without any commit. After running the above command you are on a new branch "NEWBRANCH", and the first commit you create from this state will start a new history without any ancestry.

	The --orphan command keeps the index and the working tree files intact in order to make it convenient for creating a new history whose trees resemble the ones from the original branch.

	Since you want to create a new empty branch that has nothing to do with the original branch, you can delete all files in the new working directory:

	from sys import argv
	import re

	# open the file and get read to read data
	file = open(argv[1], "r");
	p = re.compile("\d+");

	# initialize the graph
	vertices, edges = map(int, p.findall(file.readline()))
	graph = [[0]*vertices for _ in range(vertices)]

	#!/usr/bin/env python

	import sqlite3

	class dbopen(object):
	"""
	Simple CM for sqlite3 databases. Commits everything at exit.
	"""
	def __init__(self, path):
	self.path = path

	(in-package :cl-user)

	(eval-when (:compile-toplevel :load-toplevel :execute)
	(ql:quickload :alexandria)
	(ql:quickload :fiveam))

	(defpackage :sort
	(:use :cl)
	(:import-from :alexandria :iota)
	(:export :bubble-sort/naive :bubble-sort/not-enough :bubble-sort/knuth