Scala Functional Programming Patterns电子书

Scala Functional Programming Patterns

Table of Contents

Scala Functional Programming Patterns

Credits

About the Author

Aknowledgement

About the Reviewers

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Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Grokking the Functional Way

Abstractions

Concise expression

Functions

Immutable

Referential transparency

The problem – grouping continuous integers

Java code

Going scalaish

Thinking recursively...

Reusability – the commonality/variability analysis

The one-liner shockers

Scala idioms

Patterns and those aha! moments

The command design pattern

The strategy design pattern

Passing algorithms around

Summary

2. Singletons, Factories, and Builders

Singletons – being one and only one

Null Objects – singletons in another garb

Null Objects – the Scala way

Options are container

Scala singletons

The apply() factory method

The factory method pattern

The Scala version

Builders

Ease of object creation

Scala shines again

Summary

3. Recursion and Chasing your Own Tail

Recursive structures

Pattern matching

Deconstruction with case statements

Stack overflows

Tail recursion to the rescue

Getting the nth element of a list

An expression parser

Persistent data structures

Two forms of recursion

Summary

4. Lazy Sequences – Being Lazy, Being Good

Illusion and reality – the proxy pattern

Hibernate's lazy loading

Lazy val – calling by need

Infinite sequences – Scala streams

Recursive streams

Memoization and the flyweight pattern

Call by name

Streams are collections

Sieve of Eratosthenes

A view to a collection

Summary

5. Taming Multiple Inheritance with Traits

The iterator design pattern

Interfaces as types

The dreaded diamond

Traits – Scala's rich interfaces

Mix-ins – rich interfaces

Frills and thrills – the decorator pattern

Scala's easy and breezy decorations – stackable modifications

Dependencies injection pattern

A taste of the cake pattern

Sealed traits

Defeating the dreaded diamond

Summary

6. Currying Favors with Your Code

Functions as first-class values

Roping in a scope

Local functions – hiding and biding their time

The underscore – Scala's Swiss army knife

A taste of the curry

Type inference

Of implicits and explicits

Stylish blocks

The loan pattern

Serving the curry

Frills and thrills – decorators again

Wrapping it up

Summary

7. Of Visitors and Chains of Responsibilities

A tale of two hierarchies

The Visitor pattern

Many hues of pattern matching

De-structuring

Typed patterns

Pattern guards

Tuple explosion

Partial functions

Visitor pattern – the Scala way

Lifting it up

The chain of responsibility

Scalaish Chain Of Responsibilities

Match and mismatch – the collect idiom

Summary

8. Traversals – Mapping/Filtering/Folding/Reducing

Iterating the Scala way

A validation problem

Setting the stage

First cut–using arrays

Second cut–using a map

Third cut–using a for expression

Fourth cut–using foldLeft

Fifth cut–using andThen

Sixth cut–using compose

Foreach–sugary sweetener

One generator

A generator and a filter

Two generators

Monads

Reduce

Summary

9. Higher Order Functions

The strategy design pattern

A strategy in Scala land

Functors

Maps

Monads

FlatMap

Monoids

An inverted index

Pipes and filters

Pipes and filters – the Scala version

It is a Monoid

Lazy collections

Summary

10. Actors and Message Passing

The recursive grep

The producer/consumer pattern

Threads – masters and slaves

Events

Immutability is golden

Akka actors take the stage

Summary

11. It's a Paradigm Shift

Verbosity

Sorting it out!

Sorted

SortBy

SortWith

Scalaish Schwartzian transform

Functional error handling

Pattern matching

Threads and futures

Scala's Futures

Parser combinators

Summary

Index