Enums / Tagged Unions

Enums in Mux are tagged unions (also called algebraic data types or sum types) that can hold different variants with associated data.

Basic Enum Definition

basic_enum.mux

Key Points:

Each variant is a case of the enum
Variants can carry associated data (or none)
Variants are constructed using .new() syntax

Creating Enum Instances

creating_enums.mux

Pattern Matching with Enums

Use match to handle different enum variants:

pattern_matching_enums.mux

Ignoring Associated Data

Use _ to ignore data you don't need:

ignoring_enum_data.mux

Pattern Matching with Guards

Add conditional logic with guards:

enum_guards.mux

Generic Enums

Enums can be generic over type parameters:

enum_generics.mux

Common Enum Patterns

optional Values

optional_values.mux

result Types for Error Handling

result_types.mux

See Error Handling for more details on result and optional.

State Machines

state_machines.mux

Nested Enums

nested_enums.mux

Enums in Collections

enums_in_collections.mux

Exhaustiveness Checking

Mux enforces exhaustive pattern matching - all variants must be covered:

exhaustiveness_checking.mux

Best Practices

Use enums for mutually exclusive states - Better than multiple booleans
Match exhaustively - Don't overuse wildcard patterns
Use guards for additional logic - Cleaner than nested if statements
Ignore unused data with _ - Makes intent explicit
Prefer result over exceptions - Explicit error handling
Prefer optional over null - No null pointer errors
Use generic enums for reusable patterns - Option<T>, result<T, E>

Basic Enum Definition​

Creating Enum Instances​

Pattern Matching with Enums​

Ignoring Associated Data​

Pattern Matching with Guards​

Generic Enums​

Common Enum Patterns​

optional Values​

result Types for Error Handling​

State Machines​

Nested Enums​

Enums in Collections​

Exhaustiveness Checking​

Best Practices​

See Also​