Seven more languages in seven weeks

312 Pages·2014·5.823 MB·English

by  Bruce Tate, Fred Daoud, Ian Dees, Jack Moffitt

Early praise for Seven More Languages in Seven Weeks
I’m tired of learning new programming languages and thought seven additional
somewhat esoteric languages wouldn’t be very useful. I couldn’t have been more
wrong. I loved it. The languages were suitably interesting and compellingly pre-
sented, and I now want to experiment with them.
➤ Brian Sletten
President, Bosatsu Consulting, Inc.
Languages are not just new syntax, they are new ways of thinking about problems.
What is the best way to think about user interfaces or scientific computing or
distributed systems or safety guarantees? As you dive into each of the languages
in this book you will get a glimpse of new abstractions and principles that will
help you write better programs in any language. Do it!
➤ Evan Czaplicki
Creator of Elm, Prezi
If you think reading a book about programming languages won’t change your
thinking about programming, I dare you to read the chapter on Idris—unless the
idea of reasoning about your C++ (or C# or Java) code more clearly and reducing
hundreds or thousands of lines of code down to two is not appealing to you, of
course.
➤ Ted Neward
Author, speaker, mentor, Neward and Associates, LLC
Just as an artist’s choice of oil, acrylic, or watercolor paint constrains the range
of effects they can achieve, the languages we choose constrain the programs we
can write. Learning a new language enables you to both conceive new solutions
and express them in new ways. Read this book to add seven particularly interesting
languages to your repertoire.
➤ Paul Butcher
Author of Seven Concurrency Models in Seven Weeks
Seven More Languages in Seven Weeks is a well-paced introduction to a set of
fascinating languages that will be new to many. This one goes at just the right
tempo and provides enough detail to be useful—but not so much as to douse
natural curiosity. Definitely a book I would recommend to others wanting to expand
their programming horizons.
➤ Matthew Wild
Author, Prosody IM XMPP server
Seven More Languages in Seven Weeks not only introduces us to a wide spectrum
of languages, but also challenges us on how we think about language use and
design. Software development is a demanding career and learning new languages
will always be essential. That is why the Seven in Seven series is one of the most
invaluable reads for any serious programmer.
➤ Daniel Hinojosa
Developer, speaker, instructor, author of Testing in Scala
Seven More Languages in Seven Weeks
Languages That Are Shaping the Future
Bruce A. Tate
Fred Daoud
Ian Dees
Jack Moffitt
The Pragmatic Bookshelf
Dallas, Texas • Raleigh, North Carolina
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The team that produced this book includes:
Jacquelyn Carter (editor)
Potomac Indexing, LLC (index)
Liz Welch (copyedit)
Dave Thomas (layout)
Janet Furlow (producer)
Ellie Callahan (support)
For international rights, please contact [email protected].
Copyright © 2014 The Pragmatic Programmers, LLC.
All rights reserved.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted,
in any form, or by any means, electronic, mechanical, photocopying, recording, or otherwise,
without the prior consent of the publisher.
Printed in the United States of America.
ISBN-13: 978-1-941222-15-7
Encoded using the finest acid-free high-entropy binary digits.
Book version: P2.0—November 2015
Contents
Foreword . . . . . . . . . . . . . vii
Acknowledgments . . . . . . . . . . . ix
Introduction . . . . . . . . . . . . . xv
1. Lua . . . . . . . . . . . . . . . 1
Day 1: The Call to Adventure 2
Day 2: Tables All the Way Down 14
Day 3: Lua and the World 32
Wrapping Up Lua 47
2. Factor . . . . . . . . . . . . . . 49
Day 1: Stack On, Stack Off 50
Day 2: Painting the Fence 61
Day 3: Balancing on a Boat 73
Wrapping Up Factor 86
3. Elm . . . . . . . . . . . . . . . 89
Day 1: Handling the Basics 90
Day 2: Taming Callbacks 100
Day 3: It’s All a Game 111
Wrapping Up Elm 123
4. Elixir . . . . . . . . . . . . . . 125
Day 1: Laying a Great Foundation 126
Day 2: Controlling Mutations 142
Day 3: Spawning and Respawning 158
Wrapping Up Elixir 167
5. Julia . . . . . . . . . . . . . . 171
Day 1: Resistance Is Futile 172
Day 2: Getting Assimilated 183
Contents • vi
Day 3: Become One with Julia 195
Wrapping Up Julia 206
6. miniKanren . . . . . . . . . . . . 209
Day 1: Unified Theories of Code 210
Day 2: Mixing the Logical and Functional 220
Day 3: Writing Stories with Logic 228
Wrapping Up miniKanren 240
7. Idris . . . . . . . . . . . . . . 243
Day 1: The Basics 244
Day 2: Getting Started With Dependent Types 253
Day 3: Dependent Types in Action 262
Wrapping Up Idris 274
8. Wrapping Up . . . . . . . . . . . . 277
The Origins 277
The Central Expressway 279
The Frontier 281
The Dirty Map 282
A Final Challenge 284
Bibliography . . . . . . . . . . . . 285
Index . . . . . . . . . . . . . . 287
Foreword
Back in 2010, I was deeply troubled. The growing list of difficulties in writing
concurrent software was nagging at me. The tools I had at hand were clunky,
and none of them provided a mental model that helped me reason about the
problems I was facing.
I decided it was time for a change.
However, out of the hundreds of programming languages out there, how could
I possibly find one that fit my criteria? How could I even filter this huge set
into a smaller one that I could explore in more detail? Then I found that
someone had decided to tell the exact story I wanted to hear: Bruce Tate had
just written Seven Languages in Seven Weeks, which explored Ruby, Io, Prolog,
Erlang, Scala, Clojure, and Haskell.
I was familiar with many of the languages in Seven Languages in Seven Weeks
but the book did more than just introduce programming language constructs.
It introduced their philosophy, community, and thinking models. To me, the
book was telling a story about concurrency, and as I read the book, a very
clear picture about immutability, threads, futures, actors, software transac-
tional memory, and more was being painted.
Once I finished the book, I knew exactly which languages and paradigms I
wanted to explore next. I bought a heap of books about Erlang, Clojure, and
Haskell and I also started writing code right away.
Months later, though, I still hadn’t found one language that fit all my criteria.
I wanted the robustness and distribution of the Erlang VM, but I also wanted
the metaprogramming and polymorphism from Clojure alongside a syntax I
was comfortable with. That’s when I decided to create the Elixir programming
language that runs on the Erlang virtual machine.
Now, four years later, Elixir is one of the languages covered in Seven More
Languages in Seven Weeks.
report erratum • discuss
Foreword • viii
The interesting thing is that the first book was not a story about concurrency
but that’s how I read it. Seven Languages in Seven Weeks, as any other
excellent book, gives space for the reader to include her own experiences as
part of the story, allowing each reader to learn different lessons and, in this
particular case, choose other languages to explore next.
This is what makes Seven More Languages in Seven Weeks even more ambi-
tious. Many of the languages in the book are relatively new and in active
development, which brings a whole new range of ideas and lessons to be
learned. It also opens up the possibility for readers to pick their next languages
and not only master them but become part of the language development itself.
Seven Languages in Seven Weeks had a deep impact on my programming
career, and I am certain reading this book will do the same for yours.
And remember: Reading Seven More Languages in Seven Weeks is just the
start of a journey.
José Valim
Creator of Elixir
report erratum • discuss