Functional Java
Functional Java
with Vavr
About the Book
online fiddle list used throughout the book :
github repos:
About the Author
Table of Contents
-
1 Language Functional support
- 1.1 Pure functions and Side effects ... 6
- 1.2 Functional Interfaces ... 9
- 1.3 Function Composition ... 15
- 1.3.1 Function<,> andThen method ... 15
- 1.3.2 BiFunction<> Composition ... 16
- 1.3.3 Supplier<> Composition ... 17
- 1.3.4 Consumer<> Composition ... 17
- 1.3.5 Predicate<> Composition ... 19
- 1.4 Vavr’s Functional Interfaces ... 20
- 1.5 Currying and partial application ... 21
- 1.5.1 Currying and partial application with Vavr ... 24
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2 Functors
- 2.1 The Identity Functor ... 26
- 2.2 Commutative Diagrams ... 27
- 2.3 The Functor Laws ... 28
- 2.4 Pattern Matching ... 30
- 2.4.1 The Basic Functor Mechanics ... 36
- 2.5 IO Functor, a Lazy Id Functor ... 37
- 2.5.1 Supplier as a Functor ... 37
- 2.6 Maybe Functor – Optional and Option ... 38
- 2.6.1 Dealing with null ... 38
- 2.6.2 The Null Object Design pattern ... 39
- 2.6.3 The Functional equivalent - Maybe as Functor ... 41
- 2.6.4 Java native Maybe aka Optional ... 43
- 2.6.5 Maybe Functor Example with java Optional ... 44
- 2.6.6 Maybe in Vavr aka Option ... 45
- 2.6.7 Maybe Functor Example with Vavr Option ... 46
- 2.7 Either Functor ... 48
- 2.7.1 Pattern matching for Either ... 50
- 2.7.2 Either in Vavr ... 50
- 2.7.3 Either Functor Example ... 51
- 2.7.4 Vavr’s pattern matching Support for Either ... 53
- 2.7.5 Using Either for exception handling ... 54
- 2.8 Explicitly Compositing Functor ... 56
- 2.9 Extending CompletableFuture to Functor ... 58
- 2.10 Combining Future and Optional - Future> ... 60
- 2.11 Combining Future and Option - Future> ... 62
- 2.12 Combining Future and Either - Future> ... 64
-
3 Monads
- 3.1 The Stream Monad ... 68
- 3.2 Maybe Monad ... 68
- 3.3 The Java Optional Monad Example ... 70
- 3.3.1 Using Vavr Option ... 72
- 3.4 Either Monad ... 72
- 3.4.1 Using Either Monad for exception handling ... 74
- 3.4.2 Using Either for Validation ... 75
- 3.5 Validation Monad ... 76
- 3.5.1 Using Validation.Apply to Collect validations ... 77
- 3.6 CompletableFuture as Monad ... 78
- 3.7 The CompletableFuture - Optional Monad Combination ... 80
- 3.8 The CompletableFuture - Option Monad Combination ... 82
- 3.9 The CompletableFuture - Either Monad Combination ... 85
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4 A Clean Functional Architecture Example
- 4.1 Download and Setup the Project ... 87
- 4.1.1 Clean Architecture with Spring Boot ... 88
- 4.2 A Functional Applications Architecture ... 90
- 4.3 Clean Architecture with Spring Boot and Vavr.io ... 91
- 4.4 Web Api ... 92
- 4.5 Domain Model ... 93
- 4.5.1 Repositories ... 96
- 4.6 CQRS ... 97
- 4.7 CQRS and Mediator Design Pattern ... 99
- 4.7.1 The Command Pattern with a Mediator ... 99
- 4.7.2 Query Workflow ... 102
- 4.7.3 Command Workflow ... 106
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