Feldman R. / Фельдман Р. - Elm in Action / Elm в действии [2020, PDF, ENG]

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preface xi
acknowledgments xiii
about this book xv
about the author xix
about the cover illustration xx
PART 1 GETTING STARTED ............................................... 1
1 Welcome to Elm 3
1.1 How Elm fits in 5
1.2 Expressions 7
Using elm repl 7 ■ Building expressions 8 ■ Booleans and
conditionals 11
1.3 Functions 13
Defining functions 14 ■ Importing functions 15 ■ Creating
scope with let-expressions 18 ■ Anonymous functions 19
Operators 20
1.4 Collections 22
Lists 23 ■ Records 24 ■ Tuples 26
2 Your first Elm application 29
2.1 Rendering a page 30
Describing a page using the Html module 31 ■ Building a project 37viii CONTENTS
2.2 Handling user input with The Elm Architecture 40
Representing application state with a model 40 ■ Handling events
with messages and updates 48
3 Compiler as assistant 55
3.1 Documenting guarantees with type annotations 56
Adding optional type annotations 56 ■ Annotating functions
with type variables 58 ■ Reusing annotations with type
aliases 61 ■ Annotating longer functions 62
3.2 Using case-expressions and custom types 65
Using case-expressions 65 ■ Enumerating possibilities with custom
types 67 ■ Holding data in custom types 71 ■ Representing
flexible messages with custom types 74
3.3 Generating random numbers with commands 77
Describing random values with Random.Generator 77
Introducing commands to The Elm Architecture 78 ■ Generating
random values with Random.generate 80
PART 2 PRODUCTION-GRADE ELM .................................. 89
4 Talking to servers 91
4.1 Preparing for server-loaded data 92
Modeling incremental initialization 92 ■ Resolving
data dependencies 95
4.2 Fetching data from a server 100
Describing HTTP requests 100 ■ Sending HTTP
requests 104
4.3 Decoding JSON 111
Decoding JSON strings into results 111 ■ Decoding
JSON collections 112 ■ Decoding JSON HTTP
responses 117
5 Talking to JavaScript 125
5.1 Using custom elements 126
Importing custom elements 127 ■ Handling custom events 133
Responding to slider changes 137
5.2 Sending data to JavaScript 141
Creating a command by using a port 141 ■ Receiving data from
Elm 146 ■ Timing DOM updates 150CONTENTS ix
5.3 Receiving data from JavaScript 152
Receiving real-time data from JavaScript via ports 152 ■ Receiving
initialization arguments via flags 156
6 Testing 167
6.1 Writing unit tests 168
Introducing tests 168 ■ Unit testing a JSON decoder 172
Narrowing test scope 176
6.2 Writing fuzz tests 180
Converting unit tests to fuzz tests 180 ■ Testing update
functions 184 ■ Creating multiple tests with one function 186
6.3 Testing views 188
Testing DOM structure 189 ■ Fuzzing view tests 193
Testing user interactions 196
PART 3 BUILDING BIGGER ............................................ 203
7 Data modeling 205
7.1 Storing values by keys in dictionaries 206
Setting up the page 207 ■ Storing photos by URL in a
dictionary 209
7.2 Modeling trees by using recursive custom types 218
Defining trees by using custom types 218 ■ Recursive
messages 223 ■ Event handlers with recursive messages 226
7.3 Decoding graphs and trees 228
Decoding dictionaries 228 ■ Decoding recursive JSON 231
Accumulating while decoding 235
8 Single-page applications 246
8.1 Framing the page 247
Creating Main.elm 247 ■ Rendering the header and footer 249
Skipping unnecessary renders with Html.Lazy 253
8.2 Routing 258
Handling the initial URL 258 ■ Parsing URL paths 263
Handing URL changes 267
8.3 Delegating pages 272
Revising module structure 272 ■ Initializing page states 275
Delegating page logic 279x CONTENTS
appendix A Getting set up 291
appendix B Installing Elm packages 294
appendix C Html.Lazy’s change check 298
index 303