Book Image

Learn Red ? Fundamentals of Red

By : Ivo Balbaert

Book Image

Learn Red ? Fundamentals of Red

By: Ivo Balbaert

Overview of this book

A key problem of software development today is software bloat, where huge toolchains and development environments are needed in software coding and deployment. Red significantly reduces this bloat by offering a minimalist but complete toolchain. This is the first introductory book about it, and it will get you up and running with Red as quickly as possible. This book shows you how to write effective functions, reduce code redundancies, and improve code reuse. It will be helpful for new programmers who are starting out with Red to explore its wide and ever-growing package ecosystem and also for experienced developers who want to add Red to their skill set. The book presents the fundamentals of programming in Red and in-depth informative examples using a step-by-step approach. You will be taken through concepts and examples such as doing simple metaprogramming, functions, collections, GUI applications, and more. By the end of the book, you will be fully equipped to start your own projects in Red.

Preface

Who this book is for

What this book covers

To get the most out of this book

Free Chapter

Red's Mission

Technical requirements

A short history of Red

What makes Red special?

Red's main features

Setting Up for Development

Setting Up for Development

Technical requirements

Working interactively in the Red console

Running and compiling your first script

Other compilation options

Red's compilation model

Development environments for writing Red

Using Words, Values, and Types

Using Words, Values, and Types

Technical requirements

Understanding words and values

Some common datatypes

Using blocks and parens

More about types

Evaluating expressions and blocks

The structure of a Red program

Further reading

Code-Controlling Structures

Code-Controlling Structures

Technical requirements

Getting input from the user – input and ask

Testing conditions

Structuring repetitions

A number-guessing game

Handling errors

Creating and catching errors

Working with Series and Blocks

Working with Series and Blocks

Technical requirements

Series and blocks

Navigating and looping through a series

Getting information from a series

Changing a series

Copying a series

Strings as series

Using Functions and Objects

Using Functions and Objects

Technical requirements

A fauna of functions

Function attributes

Working with functions

Code is data and data is code

Working with Files

Working with Files

Technical requirements

Selecting a file or folder

Working with file paths and directories

Reading and writing data files

Loading and saving files

Downloading currency exchange rates

Parsing Data

Technical requirements

The bitset! datatype

Understanding how parse works

Searching, extracting, and changing

More features and examples

Composing Visual Interfaces

Composing Visual Interfaces

Technical requirements

Structuring an interface

A faces walkthrough

Events and actors

Basic contacts app

An introduction to the draw dialect

Further reading

Advanced Red

Technical requirements

Reactive programming

Interacting with the operating system

Datatypes for performance

Embedded Red and macros

Red for smart contract programming

Some useful references

Further reading

Assessments

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Downloading currency exchange rates

At the end of the Reading and writing files section, we learned how to download files from the internet. Let's use this knowledge to download some currency exchange rates data from Floatrates (http://www.floatrates.com/). As one of its many services, this website offers the current exchange rates of any currency compared to most common currencies. These rates can be obtained in XML or JSON format. For example, the URL http://www.floatrates.com/daily/USD.xml shows a spreadsheet layout of currencies compared to the US dollar (USD):

For example, today (Mar 23, 2018) it shows that 1 USD is worth 0.81191502 Euros (EUR). The resource for this nice web page is an XML file, in which all exchange rate data are stored, in our case, USD.xml.

We now know how to download this data and store it in a local rates.xml file for further processing:

;-...