Variants

Welcome to the second chapter of the intermediates guide. In this chapter we look at the variant type and what you can do with it. The variant type is used to define a type that could be one of a given collection of other types. Where optionalls allowed us to define emptiness, the variant type allows us to define variation in types.

What are Variants?

A variant is, once again, essentially just a struct under the hood. It is composed of a 1 Byte flag value to determine which type it holds followed by the actual type of the variant. This "type" as the second value is just N bytes of storage, where N is the number of bytes needed to store the biggest of all possible types.

Why are Variants Important?

Variants are an essential part of Flint because they allow you to:

• Describe the possibility that a value might be one of a given kind
• Store multiple different "data" in a very small space, as the variant does not occupy space for each value it could be

What to Expect

In this chapter, we will cover the following topics:

• Declaring and using variant types
• Tagging variants
• Variant Comparison
• Force-unwrapping a variant variable
• Switching on variant values
• Building optional chains through the variant extraction operator
• Making variants optional and how variants interact with optionals