Haskell in Depth

665 Pages·2021·15.392 MB·English

by  Vitaly Bragilevsky

Vitaly Bragilevsky
Foreword by Simon Peyton Jones
M A N N I N G
Selected examples inside the book
Name Main features Section
Extracting a Designing a small functional program 1.2–1.4
vocabulary Using OverloadedStrings GHC extension
Working with Text from the text package
Formatting texts with fmt
Manipulating a Using type classes with derived instances 2.1
radar antenna
Defining your own type classes
Implementing type class instances
Exploiting randomness for testing
Arithmetic Converting recursive datatype values to Text 2.2, 5.2,
expressions Implementing stateful imperative algorithms with the State monad 6.1, 7.2,
11.4
Exploiting complex monad transformer stacks with mtl
Handling exceptions in monad stacks
Controlling domain types with GADTs (generalized algebraic data types)
Stock quotes Structuring a program with modules 3.1–3.3
Plotting graphs with Chart and Chart-diagrams
Generating HTML with blaze-html
Processing command-line arguments with optparse-applicative
Reading CSV files with cassava
Generating SQL Processing potentially incorrect data with logging errors in the Writer monad 5.1, 12.2
Using the traverse function
Applying GHC.Generics to generating SQL queries from data type declarations
Disk usage Manipulating files and directories 6.2
Working in IO-based monad transformer stacks
Sunrise and Dealing with times and time zones 7.4
sunset Parsing JSON with aeson
Making HTTP requests with req
Designing an exception-handling strategy
(Continues on inside back cover)
Haskell in Depth
VITALY BRAGILEVSKY
FOREWORD BY SIMON PEYTON JONES
MANNING
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To my mother

brief contents
P 1 C H ................................................................1
ART ORE ASKELL
1 ■ Functions and types 3
2 ■ Type classes 18
3 ■ Developing an application: Stock quotes 60
P 2 I ............................97
ART NTRODUCTION TO APPLICATION DESIGN
4 ■ Haskell development with modules, packages,
and projects 99
5 ■ Monads as practical functionality providers 132
6 ■ Structuring programs with monad transformers 170
P 3 Q .....................................................203
ART UALITY ASSURANCE
7 ■ Error handling and logging 205
8 ■ Writing tests 246
9 ■ Haskell data and code at run time 281
10 ■ Benchmarking and profiling 310
v
vi BRIEF CONTENTS
P 4 A H ......................................................341
ART DVANCED ASKELL
11 ■ Type system advances 343
12 ■ Metaprogramming in Haskell 387
13 ■ More about types 435
P 5 H ........................................................477
ART ASKELL TOOLKIT
14 ■ Data-processing pipelines 479
15 ■ Working with relational databases 530
16 ■ Concurrency 567
contents
foreword xv
preface xvii
acknowledgments xxiv
about this book xxvi
about the author xxxii
about the cover illustration xxxiii
P 1 C H ......................................................1
ART ORE ASKELL
1 Functions and types 3
1.1 Solving problems in the GHCi REPL with functions 4
1.2 From GHCi and String to GHC and Text 6
1.3 Functional programs as sets of IO actions 7
1.4 Embracing pure functions 10
Separating I/O from pure functions 10 ■ Computing the most
frequent words by sorting them 13 ■ Formatting reports 14
Rule them all with IO actions 17
vii
viii CONTENTS
2 Type classes 18
2.1 Manipulating a radar antenna with type classes 19
The problem at hand 19 ■ Rotating a radar antenna with Eq,
Enum, and Bounded 21 ■ Combining turns with Semigroup and
Monoid 26 ■ Printing and reading data with Show and
Read 30 ■ Testing functions with Ord and Random 33
2.2 Issues with numbers and text 38
Numeric types and type classes 38 ■ Numeric conversions 40
Computing with fixed precision 41 ■ More about Show and
Read 43 ■ Converting recursive types to strings 47
2.3 Abstracting computations with type classes 51
An idea of a computational context and a common behavior 51
Exploring different contexts in parallel 53 ■ The do notation 54
Folding and traversing 56
3 Developing an application: Stock quotes 60
3.1 Setting the scene 61
Inputs 62 ■ Outputs 62 ■ Project structure 64
3.2 Exploring design space 68
Designing the user interface 69 ■ Dealing with input data 70
Formatting reports 72 ■ Plotting charts 73
Project dependencies overview 74
3.3 Implementation details 75
Describing data 76 ■ Plotting charts 80 ■ Preparing reports 85
Implementing the user interface 92 ■ Connecting parts 94
P 2 I ...................97
ART NTRODUCTION TO APPLICATION DESIGN
4 Haskell development with modules, packages, and projects 99
4.1 Organizing Haskell code with modules 100
Module structure, imports and exports, and module hierarchy 100
Custom Preludes 105 ■ Example: containers-mini 107
4.2 Understanding Haskell packages 111
Packages at the GHC level 111 ■ Cabal packages and Hackage 114
4.3 Tools for project development 121
Dependency management 122 ■ Haskell projects as a collection of
packages 127 ■ Common project management activities and
tools 129