Overview

You can read this document from top to bottom, but it’s advisable to jump through sections because some concepts are interrelated and can’t be explained in isolation.

In code examples, the comment #=> is used to show the value of an expression. For example:

  1. a = 1 + 2
  2. a #=> 3

A comment using : is used for showing the type of a variable.

  1. s = "hello"
  2. # s : String

Let’s start with two examples to familiarize ourselves with the language.