Bryan O'Sullivan

Bryan O'Sullivan

Haskell hacker, distributed systems guy, writer, climber

San Francisco, California

Areas of Expertise:

  • Haskell
  • functional programming
  • distributed systems
  • revision control tools
  • Mercurial
  • consulting
  • speaking
  • programming
  • training
Bryan O'Sullivan is an Irish writer and developer who works with distributed systems, open source software, and programming languages. He wrote the award-winning O'Reilly title Real World Haskell. He has made significant contributions to the popular Mercurial revision control system, and to a number of other open source projects. He lives in San Francisco with his family. Whenever he can, he runs off to climb rocks.

Mercurial: The Definitive Guide Mercurial: The Definitive Guide
by Bryan O'Sullivan
June 2009
Print: $39.99
Ebook: $35.99

Real World Haskell Real World Haskell
by Bryan O'Sullivan, John Goerzen, Donald Bruce Stewart
November 2008
Print: $49.99
Ebook: $39.99

Bryan blogs at:

Photo-Development Challenge Results #2: Statues

May 22 2015

It's been three months to the day since I posted "Photo-Development Challenge: Inspire Me and Others With Your Artistic Interpretation", and I'm mortified that it's only the second set of results that I'm finally getting around to sharing (the first having been "Hillside Temple Buildings" 2½ months ago). In retrospect,… read more

Ask the Readers: Will higher interest rates make you save more money?

May 22 2015

This article is by editor Linda Vergon. Interest rates are expected to rise later in 2015. What will you do with this information? You could make the case that you haven’t missed much if you didn’t keep your money in a savings account over the last few years. But still,… read more

Four short links: 22 May 2015

May 22 2015

GM: That Car You Bought, We’re Really the Ones Who Own It — GM’s claim is all about copyright and software code, and it’s the same claim John Deere is making about their tractors. The TL;DR version of the argument … read more

Four short links: 22 May 2015

May 22 2015

GM: That Car You Bought, We’re Really the Ones Who Own It — GM’s claim is all about copyright and software code, and it’s the same claim John Deere is making about their tractors. The TL;DR version of the argument … read more

A “have-coffee” culture

May 21 2015

Download a free copy of Building an Optimized Business, a curated collection of chapters from the O’Reilly Web Operations and Performance library. This post is an excerpt by J. Paul Reed from DevOps in Practice, one of the selections included … read more

A “have-coffee” culture

May 21 2015

Download a free copy of Building an Optimized Business, a curated collection of chapters from the O’Reilly Web Operations and Performance library. This post is an excerpt by J. Paul Reed from DevOps in Practice, one of the selections included … read more

Cultivating change

May 21 2015

Attend Cultivate July 20 and 21, in Portland, Oregon. Cultivate is our conference looking at the challenges facing modern management and aiming to train a new generation of business leaders who understand the relationship between corporate culture and corporate prosperity. … read more

What today’s fitness technology means for tomorrow’s office

May 21 2015

Contributing Author: Claire Niech Attend O’Reilly’s Solid Conference, June 23–25, in San Francisco. Solid is our conference exploring how the collision of software and hardware is fueling the creation of a software-enhanced, networked physical world. At 5:37 a.m., Nina’s alarm … read more

"I would recommend this book to anyone serious about learning Haskell or becoming better at functional programming. The authors do an excellent job of conveying why Haskell does things in certain ways, which leads to a better understanding of the language."
--Michael Dumont, Computer Science House

"Real World Haskell is the first Haskell introduction I've read that actually helped me understand why anyone would want to use the language. The focus on programming methods instead of just syntax made it much easier to think of practical applications for the language."
--Byron Clark, Amazon.com

"This is one of the best programming books that came out in recent years regardless of language."
--Gregory Knapen, Amazon.com

"I tried to learn Ocaml or Haskell before but was put off by the books available. This book is really different. It made me love Haskell."
--Emad S. Mohamed "Nawfal", Amazon.com

"For those who know a conventional language, this book will make you fall in love with Haskell."
--David Crawshaw, Amazon.com

"The book is a must-read for not only people who would specifically like to learn Haskell, but for any programmer who is open to new ways of thinking about computing. "
--Evgeny Kirpichov, Amazon.com

"The hardest problems in modern software lie in performance, modularity, reliability, and concurrency. With Real World Haskell, the authors do a great job of teaching how to tackle each of these problems with Haskell, a language that is generations ahead of today's mainstream."
--Tim Sweeney, founder of Epic Games, and designer of the Unreal game engine

"...this book will expand your mind. It will give you a new way of thinking about the whole enterprise of programming: when you have worked through these pages, you'll write better code in your current favourite language."
--Simon Peyton Jones, Microsoft Research, Haskell language architect and designer of the Glasgow Haskell Compiler

"This book is exactly what's needed--a deep and comprehensive guide, covering everything from fundamentals to a wealth of advanced topics, aimed at experienced programmers who want to harness Haskell's power to get the job done. I will be using it in my Advanced Programming classes from now on."
--Benjamin Pierce, Professor, Department of Computer and Information Science, University of Pennsylvania, author of Types and Programming Languages