Programming in Scala: Updated for Scala 2.12 : a comprehensive step-by-step guide

859 Pages·2016·3.64 MB·English

by  Martin Odersky

A comprehensive step-by-step guide
Programming in
Scala
Third Edition
Updated for Scala 2.12
Martin Odersky
Lex Spoon
artima
Bill Venners
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
Praise for the earlier editions of
Programming in Scala
Programming in Scala is probably one of the best programming books
I’veeverread. Ilikethewritingstyle,thebrevity,andthethoroughexplana-
tions. The book seems to answer every question as it enters my mind—it’s
always one step ahead of me. The authors don’t just give you some code
andtakethingsforgranted. Theygiveyouthemeatsoyoureallyunderstand
what’sgoingon. Ireallylikethat.
-KenEgervari,ChiefSoftwareArchitect
Programming in Scala is clearly written, thorough, and easy to follow.
It has great examples and useful tips throughout. It has enabled our organi-
zation to ramp up on the Scala language quickly and efficiently. This book
is great for any programmer who is trying to wrap their head around the
flexibilityandeleganceoftheScalalanguage.
-LarryMorroni,Owner,MorroniTechnologies,Inc.
The Programming in Scala book serves as an excellent tutorial to the
Scala language. Working through the book, it flows well with each chapter
buildingonconceptsandexamplesdescribedinearlierones. Thebooktakes
care to explain the language constructs in depth, often providing examples
of how the language differs from Java. As well as the main language, there
isalsosomecoverageoflibrariessuchascontainersandactors.
I have found the book really easy to work through, and it is probably
oneofthebetterwrittentechnicalbooksIhavereadrecently. Ireallywould
recommendthisbooktoanyprogrammerwantingtofindoutmoreaboutthe
Scalalanguage.
-MatthewTodd
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
iii
IamamazedbytheeffortundertakenbytheauthorsofProgrammingin
Scala. ThisbookisaninvaluableguidetowhatIliketocallScalathePlat-
form: avehicletobettercoding,aconstantinspirationforscalablesoftware
design and implementation. If only I had Scala in its present mature state
andthisbookonmydeskbackin2003,whenco-designingandimplement-
ingpartsoftheAthens2004OlympicGamesPortalinfrastructure!
To all readers: No matter what your programming background is, I feel
you will find programming in Scala liberating and this book will be a loyal
friendinthejourney.
-ChristosKKLoverdos,SoftwareConsultant,Researcher
ProgramminginScalaisasuperbin-depthintroductiontoScala,andit’s
alsoanexcellentreference. I’dsaythatitoccupiesaprominentplaceonmy
bookshelf,exceptthatI’mstillcarryingitaroundwithmenearlyeverywhere
Igo.
-BrianClapper,President,ArdenTex,Inc.
Greatbook,wellwrittenwiththoughtfulexamples. Iwouldrecommend
ittobothseasonedprogrammersandnewbies.
-HowardLovatt
The book Programming in Scala is not only about how, but more im-
portantly,whytodevelopprogramsinthisnewprogramminglanguage. The
book’s pragmatic approach in introducing the power of combining object-
oriented and functional programming leaves the reader without any doubts
astowhatScalareallyis.
-Dr. ErvinVarga,CEO/founder,EXPROI.T.Consulting
ThisisagreatintroductiontofunctionalprogrammingforOOprogram-
mers. Learning about FP was my main goal, but I also got acquainted with
someniceScalasurpriseslikecaseclassesandpatternmatching. Scalaisan
intriguinglanguageandthisbookcoversitwell.
There’s always a fine line to walk in a language introduction book be-
tween giving too much or not enough information. I find Programming in
Scalatoachieveaperfectbalance.
-JeffHeon,ProgrammerAnalyst
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
iv
I bought an early electronic version of the Programming in Scala book,
by Odersky, Spoon, and Venners, and I was immediately a fan. In addition
to the fact that it contains the most comprehensive information about the
language,thereareafewkeyfeaturesoftheelectronicformatthatimpressed
me. I have never seen links used as well in a PDF, not just for bookmarks,
but also providing active links from the table of contents and index. I don’t
know why more authors don’t use this feature, because it’s really a joy for
the reader. Another feature which I was impressed with was links to the
forums(“Discuss”)andawaytosendcomments(“Suggest”)totheauthors
via email. The comments feature by itself isn’t all that uncommon, but the
simpleinclusionofapagenumberinwhatisgeneratedtosendtotheauthors
is valuable for both the authors and readers. I contributed more comments
thanIwouldhaveiftheprocesswouldhavebeenmorearduous.
Read Programming in Scala for the content, but if you’re reading the
electronic version, definitely take advantage of the digital features that the
authorstookthecaretobuildin!
-DianneMarsh,Founder/SoftwareConsultant,SRTSolutions
Lucidity and technical completeness are hallmarks of any well-written
book,andIcongratulateMartinOdersky,LexSpoon,andBillVennersona
jobindeedverywelldone! TheProgramminginScalabookstartsbysetting
a strong foundation with the basic concepts and ramps up the user to an
intermediate level & beyond. This book is certainly a must buy for anyone
aspiringtolearnScala.
-JaganNambi,EnterpriseArchitecture,GMACFinancialServices
Programming in Scala is a pleasure to read. This is one of those well-
writtentechnicalbooksthatprovidedeepandcomprehensivecoverageofthe
subjectinanexceptionallyconciseandelegantmanner.
Thebookisorganizedinaverynaturalandlogicalway. Itisequallywell
suitedforacurioustechnologistwhojustwantstostayontopofthecurrent
trends and a professional seeking deep understanding of the language core
features and its design rationales. I highly recommend it to all interested
in functional programming in general. For Scala developers, this book is
unconditionallyamust-read.
-IgorKhlystov,SoftwareArchitect/LeadProgrammer,GreystoneInc.
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
v
ThebookProgramminginScalaoutrightoozesthehugeamountofhard
work that has gone into it. I’ve never read a tutorial-style book before that
accomplishestobeintroductoryyetcomprehensive: intheir(misguided)at-
tempttobeapproachableandnot“confuse”thereader,mosttutorialssilently
ignore aspects of a subject that are too advanced for the current discussion.
Thisleavesaverybadtaste,asonecanneverbesureastotheunderstanding
one has achieved. There is always some residual “magic” that hasn’t been
explained and cannot be judged at all by the reader. This book never does
that, it never takes anything for granted: every detail is either sufficiently
explained or a reference to a later explanation is given. Indeed, the text is
extensivelycross-referencedandindexed,sothatformingacompletepicture
ofacomplextopicisrelativelyeasy.
-GeraldLoeffler,EnterpriseJavaArchitect
ProgramminginScalabyMartinOdersky,LexSpoon,andBillVenners:
intimeswheregoodprogrammingbooksarerare,thisexcellentintroduction
for intermediate programmers really stands out. You’ll find everything here
youneedtolearnthispromisinglanguage.
-ChristianNeukirchen
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
Programming in Scala
Third Edition
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
Programming in Scala
Third Edition
Martin Odersky, Lex Spoon, Bill Venners
artima
ARTIMAPRESS
WALNUTCREEK,CALIFORNIA
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
viii
ProgramminginScala
ThirdEdition
MartinOderskyisthecreatoroftheScalalanguageandaprofessoratEPFLin
Lausanne,Switzerland. LexSpoonworkedonScalafortwoyearsasapost-doc
withMartinOdersky. BillVennersispresidentofArtima,Inc.
ArtimaPressisanimprintofArtima,Inc.
P.O.Box305,WalnutCreek,California94597
Copyright©2007-2016MartinOdersky,LexSpoon,andBillVenners.
Allrightsreserved.
FirsteditionpublishedasPrePrint™eBook2007
Firsteditionpublished2008
SecondeditionpublishedasPrePrint™eBook2010
Secondeditionpublished2010
ThirdeditionpublishedasPrePrint™eBook2016
Thirdeditionpublished2016
BuilddateofthisimpressionApril6,2016
ProducedintheUnitedStatesofAmerica
Nopartofthispublicationmaybereproduced,modified,distributed,storedina
retrievalsystem,republished,displayed,orperformed,forcommercialor
noncommercialpurposesorforcompensationofanykindwithoutpriorwritten
permissionfromArtima,Inc.
Allinformationandmaterialsinthisbookareprovided"asis"andwithout
warrantyofanykind.
Theterm“Artima”andtheArtimalogoaretrademarksorregisteredtrademarksof
Artima,Inc. Allothercompanyand/orproductnamesmaybetrademarksor
registeredtrademarksoftheirowners.
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
toNastaran-M.O.
toFay-L.S.
toSiew-B.V.
Cover·Overview·Contents·Discuss·Suggest·Glossary·Index
Overview
Contents xi
ListofFigures xxi
ListofTables xxiii
ListofListings xxv
Foreword xxxii
Acknowledgments xxxiv
Introduction xxxvii
1. AScalableLanguage 45
2. FirstStepsinScala 64
3. NextStepsinScala 77
4. ClassesandObjects 99
5. BasicTypesandOperations 112
6. FunctionalObjects 135
7. Built-inControlStructures 155
8. FunctionsandClosures 180
9. ControlAbstraction 203
10. CompositionandInheritance 218
11. Scala’sHierarchy 246
12. Traits 257
13. PackagesandImports 276
14. AssertionsandTests 294
15. CaseClassesandPatternMatching 306
16. WorkingwithLists 340
17. WorkingwithOtherCollections 373
18. MutableObjects 395
19. TypeParameterization 418
20. AbstractMembers 443
21. ImplicitConversionsandParameters 474
22. ImplementingLists 499
23. ForExpressionsRevisited 512
24. CollectionsinDepth 528
25. TheArchitectureofScalaCollections 597
26. Extractors 621
27. Annotations 637
28. WorkingwithXML 645
29. ModularProgrammingUsingObjects 659
30. ObjectEquality 674
31. CombiningScalaandJava 698
32. FuturesandConcurrency 714
33. CombinatorParsing 736
34. GUIProgramming 765
35. TheSCellsSpreadsheet 777
A. ScalaScriptsonUnixandWindows 802
Glossary 803
Bibliography 819
AbouttheAuthors 822
Index 823
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