Book Image

C++ Reactive Programming

By : Praseed Pai, Peter Abraham
Book Image

C++ Reactive Programming

By: Praseed Pai, Peter Abraham

Overview of this book

Reactive programming is an effective way to build highly responsive applications with an easy-to-maintain code base. This book covers the essential functional reactive concepts that will help you build highly concurrent, event-driven, and asynchronous applications in a simpler and less error-prone way. C++ Reactive Programming begins with a discussion on how event processing was undertaken by different programming systems earlier. After a brisk introduction to modern C++ (C++17), you’ll be taken through language-level concurrency and the lock-free programming model to set the stage for our foray into the Functional Programming model. Following this, you’ll be introduced to RxCpp and its programming model. You’ll be able to gain deep insights into the RxCpp library, which facilitates reactive programming. You’ll learn how to deal with reactive programming using Qt/C++ (for the desktop) and C++ microservices for the Web. By the end of the book, you will be well versed with advanced reactive programming concepts in modern C++ (C++17).
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Lazy evaluation


In programming languages, there are two prominent  ways to evaluate arguments to a function they are as follows:

  • Applicative-order evaluation (AO)
  • Normal-order evaluation (NO)

In the case of AO, arguments are evaluated in the calling context, before being passed to the callee. Most conventional programming languages follow this method. In the case of NO, the evaluation of the variables is deferred until the result of the computation is warranted in the context of the callee. Some functional programming languages, such as Haskell, F#, and ML, follow the NO model. In functional programming languages, most of the evaluation of functions is referentially transparent (the invocation of the functions does not produce side-effects); we need to evaluate the expression only once (for a particular value as argument) and the result can be shared, when the evaluation with the same function with the same arguments appears once again for execution. This is called lazy evaluation. Thus, lazy...