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
Contributors
Preface
Index

Expressions and symbols


An abstract syntaxtree (AST) is a tree representation of the abstract syntactic structure of source code written in a programming language. When Julia code is parsed by its LLVM JIT compiler, it is internally represented as an abstract syntax tree. The nodes of this tree are simple data structures of the type expression Expr. For more information on abstract syntax trees, refer to http://en.wikipedia.org/wiki/Abstract_syntax_tree.

An expression is simply an object that represents Julia code. For example, 2 + 3 is a piece of code, which is an expression of type Int64 (follow along with the code in Chapter 7\expressions.jl). Its syntax tree can be visualized as follows:

To make Julia see this as an expression and block its evaluation, we have to quote it, that is, precede it by a colon (:) as in :(2 + 3). When you evaluate :(2 + 3) in the REPL, it just returns :(2 + 3), which is of type Expr: typeof(:(2 + 3)) returns Expr. In fact, the : operator (also called the quote...