Book Image

Julia 1.0 Programming - Second Edition

By : Ivo Balbaert
Book Image

Julia 1.0 Programming - Second Edition

By: Ivo Balbaert

Overview of this book

The release of Julia 1.0 is now ready to change the technical world by combining the high productivity and ease of use of Python and R with the lightning-fast speed of C++. Julia 1.0 programming gives you a head start in tackling your numerical and data problems. You will begin by learning how to set up a running Julia platform, before exploring its various built-in types. With the help of practical examples, this book walks you through two important collection types: arrays and matrices. In addition to this, you will be taken through how type conversions and promotions work. In the course of the book, you will be introduced to the homo-iconicity and metaprogramming concepts in Julia. You will understand how Julia provides different ways to interact with an operating system, as well as other languages, and then you'll discover what macros are. Once you have grasped the basics, you’ll study what makes Julia suitable for numerical and scientific computing, and learn about the features provided by Julia. By the end of this book, you will also have learned how to run external programs. This book covers all you need to know about Julia in order to leverage its high speed and efficiency for your applications.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell

Concrete and abstract types

In this hierarchy, some types, such as Number, Integer, and Signed, are abstract, which means that they have no concrete objects or values of their own. Instead, objects or values are of concrete types given by the result of applying typeof(value), such as Int8, Float64, and String. For example, the concrete type of the value 5 is Int64 given by typeof(5) (on a 64-bit machine). However, a value also has the type of all of its supertypes; for example, isa(5, Number) returns true (we introduced the isa function in the Types section of Chapter 2, Variables, Types, and Operations).

Concrete types have no subtypes and might only have abstract types as their supertypes. Schematically, we can differentiate them as follows:











An abstract type (such as Number and Real) is only a name that groups multiple subtypes together, but it can be used as a type annotation or used as a type in array literals. These types are the nodes in the...