Skip to Content
Learn Red ? Fundamentals of Red
book

Learn Red ? Fundamentals of Red

by Ivo Balbaert
May 2018
Beginner content levelBeginner
252 pages
6h 19m
English
Packt Publishing
Content preview from Learn Red ? Fundamentals of Red

The map! and hash! datatypes

Many languages have a dictionary type to efficiently store values associated with keys, and to provide fast lookup for those keys—for example, key1 -> value1, key2 -> value2, and so on. Red offers two datatypes for this, the hash! and the map!.

With hash!, you get a type that has all the navigational functionality that exists for series. When the key values are simple types, they get hashed, which results in a fast value lookup. First, you define the key, then its value, then a new key with its value, and so on:

h1: make hash! [n 13 m 42 o 108]h1/m           ;== 42select h1 [m]  ;== 42 select h1 'm   ;== 42hash? h1       ;== truehash? [n 13 m 42 o 108]   ;== false

Value lookup is done with the path notation hash / key or through ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

How I Built a Personal Board of Directors With GenAI

How I Built a Personal Board of Directors With GenAI

Vipin Gupta
How to Become a Game-Changing Leader

How to Become a Game-Changing Leader

Douglas A. Ready, Alan Mulally
Why AI Demands a New Breed of Leaders

Why AI Demands a New Breed of Leaders

Faisal Hoque, Thomas Davenport, Erik Nelson

Publisher Resources

ISBN: 9781789130706Supplemental Content