Enumerated types - The Rust Reference

# Enumerated types

An enumerated type is a nominal, heterogeneous disjoint union type, denoted by the name of an `enum` item. 1

An `enum` item declares both the type and a number of variants, each of which is independently named and has the syntax of a struct, tuple struct or unit-like struct.

New instances of an `enum` can be constructed in an enumeration variant expression.

Any `enum` value consumes as much memory as the largest variant for its corresponding `enum` type, as well as the size needed to store a discriminant.

Enum types cannot be denoted structurally as types, but must be denoted by named reference to an `enum` item.

1

../The `enum` type is analogous to a `data` constructor declaration in ML, or a pick ADT in Limbo.