Haskell Programming from First Principles: Pure functional programming without fear or frustation

Reader feedback....2 Contents....4 Authors' preface....21 Acknowledgements....26 Introduction....30 Why This Book....30 A few words to new programmers....35 Haskevangelism....36 What's in this book?....40 Best practices for examples and exercises....44 All You Need is Lambda....49 All You Need is Lambda....50 What is functional programming?....50 What is a function?....52 The structure of lambda terms....55 Beta reduction....58 Multiple arguments....63 Evaluation is simplification....68 Combinators....69 Divergence....71 Summary....72 Chapter Exercises....73 Answers....75 Definitions....79 Follow-up resources....81 Hello, Haskell!....82 Hello, Haskell....83 Interacting with Haskell code....84 Understanding expressions....88 Functions....91 Evaluation....95 Infix operators....98 Declaring values....105 Arithmetic functions in Haskell....115 Parenthesization....126 Let and where....133 Chapter Exercises....138 Definitions....142 Follow-up resources....144 Strings....145 Printing strings....146 A first look at types....146 Printing simple strings....148 Top-level versus local definitions....155 Types of concatenation functions....158 Concatenation and scoping....163 More list functions....167 Chapter Exercises....170 Definitions....176 Basic datatypes....179 Basic Datatypes....180 What are types?....181 Anatomy of a data declaration....181 Numeric types....185 Comparing values....195 Go on and Bool me....200 Tuples....208 Lists....213 Chapter Exercises....215 Definitions....220 Names and variables....223 Types....226 Types....227 What are types for?....228 How to read type signatures....230 Currying....240 Polymorphism....256 Type inference....265 Asserting types for declarations....270 Chapter Exercises....273 Definitions....287 Follow-up resources....294 Typeclasses....295 Typeclasses....296 What are typeclasses?....296 Back to Bool....298 Eq....300 Writing typeclass instances....305 Num....321 Type-defaulting typeclasses....326 Ord....332 Enum....342 Show....344 Read....351 Instances are dispatched by type....352 Gimme more operations....357 Chapter Exercises....362 Chapter Definitions....371 Typeclass inheritance, partial....374 Follow-up resources....374 More functional patterns....376 Make it func-y....377 Arguments and parameters....377 Anonymous functions....387 Pattern matching....392 Case expressions....408 Higher-order functions....413 Guards....425 Function composition....435 Pointfree style....440 Demonstrating composition....444 Chapter Exercises....448 Chapter Definitions....454 Follow-up resources....465 Recursion....467 Recursion....468 Factorial!....469 Bottom....479 Fibonacci numbers....483 Integral division from scratch....489 Chapter Exercises....496 Definitions....503 Lists....505 Lists....506 The list datatype....506 Pattern matching on lists....508 List's syntactic sugar....512 Using ranges to construct lists....513 Extracting portions of lists....517 List comprehensions....525 Spines and nonstrict evaluation....533 Transforming lists of values....548 Filtering lists of values....559 Zipping lists....561 Chapter Exercises....565 Definitions....574 Follow-up resources....577 Folding lists....578 Folds....579 Bringing you into the fold....579 Recursive patterns....582 Fold right....583 Fold left....596 How to write fold functions....609 Folding and evaluation....616 Summary....619 Scans....621 Chapter Exercises....626 Definitions....633 Follow-up resources....637 Algebraic datatypes....638 Algebraic datatypes....639 Data declarations review....640 Data and type constructors....642 Type constructors and kinds....645 Data constructors and values....647 What's a type and what's data?....653 Data constructor arities....659 What makes these datatypes algebraic?....662 newtype....668 Sum types....675 Product types....679 Normal form....684 Constructing and deconstructing values....690 Function type is exponential....715 Higher-kinded datatypes....722 Lists are polymorphic....725 Binary Tree....729 Chapter Exercises....738 Definitions....751 Signaling adversity....752 Signaling adversity....753 How I learned to stop worrying and love Nothing....753 Bleating either....757 Kinds, a thousand stars in your types....768 Chapter Exercises....780 Definitions....796 Building projects....798 Modules....799 Making packages with Stack....801 Working with a basic project....802 Making our project a library....807 Module exports....810 More on importing modules....813 Making our program interactive....821 do syntax and IO....827 Hangman game....832 Step One: Importing modules....835 Step Two: Generating a word list....841 Step Three: Making a puzzle....846 Adding a newtype....858 Chapter exercises....859 Follow-up resources....863 Testing....865 Testing....866 A quick tour of testing for the uninitiated....867 Conventional testing....869 Enter QuickCheck....881 Morse code....894 Arbitrary instances....911 Chapter Exercises....923 Definitions....933 Follow-up resources....934 Monoid, Semigroup....935 Monoids and semigroups....936 What we talk about when we talk about algebras....937 Monoid....938 How Monoid is defined in Haskell....940 Examples of using Monoid....941 Why Integer doesn't have a Monoid....943 Why bother?....949 Laws....951 Different instance, same representation....956 Reusing algebras by asking for algebras....959 Madness....971 Better living through QuickCheck....973 Semigroup....984 Strength can be weakness....989 Chapter exercises....992 Definitions....1003 Follow-up resources....1004 Functor....1005 Functor....1006 What's a functor?....1007 There's a whole lot of fmap goin' round....1010 Let's talk about f, baby....1013 Functor Laws....1027 The Good, the Bad, and the Ugly....1029 Commonly used functors....1035 Transforming the unapplied type argument....1053 QuickChecking Functor instances....1058 Exercises: Instances of Func....1062 Ignoring possibilities....1063 A somewhat surprising functor....1072 More structure, more functors....1076 IO Functor....1078 What if we want to do something different?....1082 Functors are unique to a datatype....1087 Chapter exercises....1089 Definitions....1094 Follow-up resources....1098 Applicative....1100 Applicative....1101 Defining Applicative....1102 Functor vs. Applicative....1105 Applicative functors are monoidal functors....1107 Applicative in use....1115 Applicative laws....1154 You knew this was coming....1163 ZipList Monoid....1168 Chapter Exercises....1183 Definitions....1186 Follow-up resources....1186 Monad....1188 Monad....1189 Sorry — a monad is not a burrito....1189 Do syntax and monads....1202 Examples of Monad use....1211 Monad laws....1236 Application and composition....1247 Chapter Exercises....1254 Definition....1257 Follow-up resources....1259 Applying structure....1260 Applied structure....1261 Monoid....1261 Functor....1269 Applicative....1274 Monad....1281 An end-to-end example: URL shortener....1285 That's a wrap!....1305 Follow-up resources....1306 Foldable....1307 Foldable....1308 The Foldable class....1309 Revenge of the monoids....1310 Demonstrating Foldable instances....1316 Some basic derived operations....1321 Chapter Exercises....1328 Follow-up resources....1329 Traversable....1330 Traversable....1331 The Traversable typeclass definition....1332 sequenceA....1333 traverse....1335 So, what's Traversable for?....1339 Morse code revisited....1340 Axing tedious code....1344 Do all the things....1348 Traversable instances....1352 Traversable Laws....1355 Quality Control....1356 Chapter Exercises....1357 Follow-up resources....1362 Reader....1363 Reader....1364 A new beginning....1365 This is Reader....1375 Breaking down the Functor of functions....1376 But uh, Reader?....1382 Functions have an Applicative too....1385 The Monad of functions....1393 Reader Monad by itself is boring....1399 You can change what comes below, but not above....1402 You tend to see ReaderT, not Reader....1403 Chapter Exercises....1403 Definition....1410 Follow-up resources....1411 State....1412 State....1413 What is state?....1413 Random numbers....1415 The State newtype....1419 Throw down....1422 Write State for yourself....1431 Get a coding job with one weird trick....1433 Chapter exercises....1440 Follow-up resources....1442 Parser combinators....1443 Parser combinators....1444 A few more words of introduction....1446 Understanding the parsing process....1447 Parsing fractions....1464 Haskell's parsing ecosystem....1473 Alternative....1477 Parsing configuration files....1492 Character and token parsers....1508 Polymorphic parsers....1513 Marshalling from an AST to a datatype....1522 Chapter Exercises....1539 Definitions....1548 Follow-up resources....1549 Composing types....1552 Composing types....1553 Common functions as types....1554 Two little functors sittin' in a tree, L-I-F-T-I-N-G....1559 Twinplicative....1562 Twonad?....1564 Exercises: Compose Instances....1566 Monad transformers....1568 IdentityT....1571 Finding a pattern....1590 Monad transformers....1594 Monad transformers....1595 MaybeT....1595 EitherT....1603 ReaderT....1605 StateT....1609 Types you probably don't want to use....1614 Recovering an ordinary type from a transformer....1616 Lexically inner is structurally outer....1618 MonadTrans....1622 MonadIO aka zoom-zoom....1645 Monad transformers in use....1649 Monads do not commute....1665 Transform if you want to....1665 Chapter Exercises....1666 Defintion....1675 Follow-up resources....1676 Nonstrictness....1677 Laziness....1678 Observational Bottom Theory....1679 Outside in, inside out....1681 What does the other way look like?....1685 Can we make Haskell strict?....1686 Call by name, call by need....1705 Nonstrict evaluation changes what we can do....1706 Thunk Life....1708 Sharing is caring....1712 Refutable and irrefutable patterns....1734 Bang patterns....1737 Strict and StrictData....1741 Adding strictness....1743 Chapter Exercises....1750 Follow-up resources....1753 Basic libraries....1755 Basic libraries and data structures....1756 Benchmarking with Criterion....1757 Profiling your programs....1775 Constant applicative forms....1780 Map....1785 Set....1789 Sequence....1792 Vector....1796 String types....1810 Chapter Exercises....1823 Follow-up resources....1827 IO....1829 IO....1830 Where IO explanations go astray....1831 The reason we need this type....1834 Sharing....1836 IO doesn't disable sharing for everything....1843 Purity is losing meaning....1845 IO's Functor, Applicative, and Monad....1848 Well, then, how do we MVar?....1854 Chapter Exercises....1857 Follow-up resources....1858 When things go wrong....1860 Exceptions....1861 The Exception class and methods....1862 This machine kills programs....1873 Want either? Try!....1880 The unbearable imprecision of trying....1885 Why throwIO?....1888 Making our own exception types....1892 Surprising interaction with bottom....1899 Asynchronous Exceptions....1901 Follow-up Reading....1905 Final project....1907 Final project....1908 fingerd....1908 Exploring finger....1910 Slightly modernized fingerd....1920 Chapter Exercises....1935