Carl carld

Reader Macros in Common Lisp

This post also appears on lisper.in.

Reader macros are perhaps not as famous as ordinary macros. While macros are a great way to create your own DSL, reader macros provide even greater flexibility by allowing you to create entirely new syntax on top of Lisp.

Paul Graham explains them very well in [On Lisp][] (Chapter 17, Read-Macros):

The three big moments in a Lisp expression's life are read-time, compile-time, and runtime. Functions are in control at runtime. Macros give us a chance to perform transformations on programs at compile-time. ...read-macros... do their work at read-time.

A lot of these are outright stolen from Edward O'Campo-Gooding's list of questions. I really like his list.

I'm having some trouble paring this down to a manageable list of questions -- I realistically want to know all of these things before starting to work at a company, but it's a lot to ask all at once. My current game plan is to pick 6 before an interview and ask those.

I'd love comments and suggestions about any of these.

I've found questions like "do you have smart people? Can I learn a lot at your company?" to be basically totally useless -- everybody will say "yeah, definitely!" and it's hard to learn anything from them. So I'm trying to make all of these questions pretty concrete -- if a team doesn't have an issue tracker, they don't have an issue tracker.

I'm also mostly not asking about principles, but the way things are -- not "do you think code review is important?", but "Does all code get reviewed?".

	;;;; SHA-1 and SHA-2 implementations.
	;;;; Uses R7RS bytevector and byte I/O interfaces.
	;;;; Requires SRFIs 1, 26, 43, and 60.

	;;; Auxiliary definitions to avoid having to use giant tables of constants.

	(define primes80 '(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73
	79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157
	163 167 173 179 181 191 193 197 199 211 223 227 229 233 239
	241 251 257 263 269 271 277 281 283 293 307 311 313 317 331

	LIST OFF
	; * E . T. T H E E X T R A - T E R R E S T R I A L *
	; Copyright 1982 Atari, Inc.
	; Designer: Howard Scott Warshaw
	; Artist: Jerome Domurat

	; Analyzed, labeled and commented
	; by Dennis Debro
	; Last Update: July 18, 2006
	;

	require 'capistrano/setup'
	require 'capistrano/deploy'

	require 'capistrano/scm'
	require 'capistrano/git'
	class Capistrano::Git < Capistrano::SCM
	module SubmoduleStrategy
	include DefaultStrategy

	def release

	# also you need to uncomment next line in Capfile
	# require 'capistrano/rails/assets'

	namespace :deploy do
	namespace :assets do

	Rake::Task['deploy:assets:precompile'].clear_actions

	desc 'Precompile assets locally and upload to servers'
	task :precompile do

	CREATE TABLE accounts(
	id serial PRIMARY KEY,
	name VARCHAR(256) NOT NULL
	);

	CREATE TABLE entries(
	id serial PRIMARY KEY,
	description VARCHAR(1024) NOT NULL,
	amount NUMERIC(20, 2) NOT NULL CHECK (amount > 0.0),
	-- Every entry is a credit to one account...

	/** @jsx React.DOM */

	var STATES = [
	'AL', 'AK', 'AS', 'AZ', 'AR', 'CA', 'CO', 'CT', 'DE', 'DC', 'FL', 'GA', 'HI',
	'ID', 'IL', 'IN', 'IA', 'KS', 'KY', 'LA', 'ME', 'MD', 'MA', 'MI', 'MN', 'MS',
	'MO', 'MT', 'NE', 'NV', 'NH', 'NJ', 'NM', 'NY', 'NC', 'ND', 'OH', 'OK', 'OR',
	'PA', 'RI', 'SC', 'SD', 'TN', 'TX', 'UT', 'VT', 'VA', 'WA', 'WV', 'WI', 'WY'
	]

	var Example = React.createClass({

	Tom Moertel <[email protected]>
	2013-12-16

	We are given the following problem:

	Given a text file with 999,999 lines, one number per line,
	numbers in random order from 1 to 1,000,000 but a single number is
	missing, figure out what number is missing.

	Source: http://blog.moertel.com/posts/2013-12-14-great-old-timey-game-programming-hack.html#comment-1165807320

	; /usr/local/bin/nasm -f macho 32.asm && ld -macosx_version_min 10.7.0 -o 32 32.o && ./32

	global start

	section .text
	start:
	push dword msg.len
	push dword msg
	push dword 1
	mov eax, 4