Optics By Example: Functional lenses in Haskell

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Table of Contents......Page 4 Why should I read this book?......Page 12 Your practice environment......Page 13 About the exercises......Page 15 Strengths......Page 17 Weaknesses......Page 18 Practical optics at a glance......Page 19 Impractical optics at a glance......Page 20 Anatomy......Page 22 Exercises – Optic Anatomy......Page 23 Viewing through lenses......Page 24 Exercises - Lens Actions......Page 25 Lenses subsume the ``accessor'' pattern......Page 26 Building a lens for a record field......Page 27 Exercises - Records Part One......Page 29 Getting and setting with a field lens......Page 30 Modifying fields with a lens......Page 31 Automatically generating field lenses......Page 32 Exercises - Records Part Two......Page 34 Is it a Lens?......Page 35 Is it a Lens? – Answers......Page 37 Why do optics have laws?......Page 40 The Laws......Page 41 Case Study: _1......Page 42 Case Study: msg......Page 43 Case Study: lensProduct......Page 44 Exercises - Laws......Page 47 What's a virtual field......Page 48 Writing a virtual field......Page 49 Breakage-free refactoring......Page 50 Exercises – Virtual Fields......Page 52 Including correction logic in lenses......Page 53 Exercises – Self-Correcting Lenses......Page 55 Simple vs Polymorphic optics......Page 57 Type-changing focuses......Page 58 Changing type variables with polymorphic lenses......Page 60 Exercises – Polymorphic Lenses......Page 61 Composing Lenses......Page 62 How do I update fields in deeply nested records?......Page 63 Composing update functions......Page 65 Composing Lenses......Page 68 How do Lens Types Compose?......Page 69 Exercises – Lens Composition......Page 73 Lens Operators......Page 75 set a.k.a. .......Page 76 Chaining many operations......Page 79 Using % a.k.a. over......Page 80 Learning Hieroglyphics......Page 81 Modifiers......Page 82 When to use operators vs named actions?......Page 83 Exercises – Operators......Page 84 Introduction to Folds......Page 88 Focusing all elements of a container......Page 89 Collapsing the Set......Page 91 Collecting focuses as a list......Page 92 Using lenses as folds......Page 94 Composing folds......Page 95 Foundational fold combinators......Page 96 Exercises – Simple Folds......Page 97 Custom Folds......Page 99 Mapping over folds......Page 101 Combining multiple folds on the same structure......Page 102 Exercises – Custom Folds......Page 103 Writing queries with folds......Page 105 Queries case study......Page 109 Folding with effects......Page 112 Combining fold results......Page 114 Using `view' on folds......Page 116 Customizing monoidal folds......Page 117 Exercises – Fold Actions......Page 119 Taking, Dropping......Page 121 Backwards......Page 126 Exercises – Higher Order Folds......Page 127 Filtered......Page 130 Fold Laws......Page 136 How do Traversals fit into the hierarchy?......Page 137 From fold to traversal......Page 138 Traversing each element of a container......Page 141 More Combinators......Page 143 Traversing multiple paths at once......Page 144 Focusing a specific traversal element......Page 146 Traversal Composition......Page 147 Exercises – Simple Traversals......Page 148 Traversal Actions......Page 149 A Primer on Traversable......Page 150 Traverse on Traversals......Page 153 Infix traverseOf......Page 156 Using Traversals directly......Page 157 Exercises – Traversal Actions......Page 158 Custom traversals......Page 159 Optics look like traverse......Page 160 Our first custom traversal......Page 161 Traversals with custom logic......Page 163 Case Study: Transaction Traversal......Page 164 Exercises – Custom Traversals......Page 167 Law One: Respect Purity......Page 168 Law Two: Consistent Focuses......Page 170 Good Traversal Bad Traversal......Page 171 partsOf......Page 172 Polymorphic partsOf......Page 176 partsOf and other data structures......Page 177 Exercises – partsOf......Page 178 What's an ``indexable'' structure?......Page 180 The Ixed Class......Page 181 Accessing and setting values with ix......Page 182 Indexing monomorphic types......Page 184 Indexing stranger structures......Page 185 Map-like structures......Page 187 Manipulating Sets......Page 189 Exercises – Indexable Structures......Page 190 Custom Ixed: Cyclical indexing......Page 191 Custom At: Address indexing......Page 193 Checking whether updates succeed......Page 196 Fallbacks with `failing'......Page 198 Default elements......Page 199 Checking fold success/failure......Page 201 Exercises – Missing Values......Page 203 Simple Pattern-Matching Prisms......Page 205 Generating prisms with makePrisms......Page 207 Embedding values with prisms......Page 209 Other types of patterns......Page 210 Exercises – Prisms......Page 213 Rebuilding _Just and _Nothing......Page 215 Matching String Prefixes......Page 217 Cracking the coding interview: Prisms style!......Page 218 Exercises – Custom Prisms......Page 220 Laws......Page 221 Law Two: Prism Complement......Page 222 Law Three: Pass-through Reversion......Page 223 Exercises – Prism Laws......Page 225 Case Study: Simple Server......Page 226 Path prefix matching......Page 228 Altering sub-sets of functions......Page 229 Matching on HTTP Verb......Page 233 There and back again......Page 236 Building Isos......Page 237 Flipping isos with from......Page 238 Modification under isomorphism......Page 239 Varieties of isomorphisms......Page 240 Composing isos......Page 243 Exercises – Intro to Isos......Page 245 Projecting Isos......Page 246 Exercises – Projected Isos......Page 249 Coercing with isos......Page 250 Newtype wrapper isos......Page 252 The one and only law: Reversibility......Page 254 Exercises – Iso Laws......Page 255 What are indexed optics?......Page 257 Index Composition......Page 259 Custom index composition......Page 261 Exercises – Indexed Optics......Page 263 Filtering by index......Page 264 Exercises – Index Filters......Page 265 Custom indexed optics......Page 266 Custom IndexedFolds......Page 267 Custom IndexedTraversals......Page 268 Index helpers......Page 270 Exercises – Custom Indexed Optics......Page 272 Index-preserving optics......Page 273 Interpreting expanded optics types......Page 275 First Foe: Level 1 Lenslion......Page 276 Level 2 Tuplicant......Page 277 Level 4 Composicore......Page 278 Level 6 Higher Order Beast......Page 279 Level 7 Traversacula......Page 280 Reader Monad and View......Page 281 State Monad Combinators......Page 282 Magnify & Zoom......Page 286 No duplicate record fields......Page 288 Separating logic and minimizing global knowledge......Page 291 Granular dependencies with makeFields......Page 293 Field requirements compose......Page 295 makeFields vs makeClassy......Page 296 Introspecting JSON......Page 301 Diving deeper into JSON structures......Page 304 Traversing Arrays......Page 305 Traversing Objects......Page 308 Filtering JSON Queries......Page 310 Serializing & Deserializing within an optics path......Page 312 Exercises: Kubernetes API......Page 316 BONUS Questions......Page 319 Optic Compatibility Chart......Page 321 Legend for Getters......Page 322 Legend for Setters/Modifiers......Page 323 Optic Ingredients......Page 324 Optic Anatomy......Page 326 Lens Actions......Page 327 Records Part One......Page 328 Records Part Two......Page 329 Laws......Page 330 Virtual Fields......Page 332 Self-Correcting Lenses......Page 334 Polymorphic Lenses......Page 336 Lens Composition......Page 338 Operators......Page 339 Simple Folds......Page 343 Writing Custom Folds......Page 345 Querying Using Folds......Page 347 Higher Order Folds......Page 350 Filtering......Page 353 Simple Traversals......Page 354 Traversal Actions......Page 355 Custom Traversals......Page 358 Traversal Laws......Page 359 partsOf......Page 360 Custom Indexed Structures......Page 362 Missing Values......Page 363 Prisms......Page 365 Custom Prisms......Page 366 Prism Laws......Page 368 Intro to Isos......Page 370 Projected Isos......Page 371 Iso Laws......Page 372 Indexed Optics......Page 373 Index Filters......Page 374 Custom Indexed Optics......Page 376 Level 2 Tuplicant......Page 378 Level 3 Settersiren......Page 379 Level 5 Foldasaurus......Page 380 Level 6 Foldasaurus......Page 381 Kubernetes API......Page 382 BONUS Questions......Page 384 Upcoming Chapters......Page 387 Patreon Supporters......Page 388 Book Cover......Page 390