AnyOf : a versatile type for Rust

This project implements a flexible and expressive binary Algebraic Data Type : AnyOf.

AnyOf is an advanced sum of product type, which enables clear, safe, and concise representations of data combinations in functional and type-driven programming.

Overview

At the core of the project is the AnyOf enum, a general-purpose algebraic type, alongside additional types such as Either and Both. These abstractions allow to express dynamic states, optional values, and branching logic in a natural and explicit manner.

Key Types

AnyOf<L, R>
- A flexible type that represents four possible states:
  - Neither: No value is present.
  - Either::Left: Only the left value is present.
  - Either::Right: Only the right value is present.
  - Both: Both values are present.
- Conceptually, it combines variants in the following way:
```
AnyOf<L, R> = Neither | Either<L, R> | Both<L, R>
```
Either<L, R>
- A simple sum type representing one of two values.
- Variants:
  - Left(L)
  - Right(R)
- Ideal for binary decision-making.
- Conceptually, it is the type :
```
Either<L, R> = Left(L) | Right(R)
```
Both<L, R>
- A product type that pairs two values, left and right, of potentially different types.
- Conceptually, it is the type :
```
Both<L, R> = (L, R)
```
Enhanced Type Composition
- Complex types like AnyOf4, AnyOf8, and AnyOf16 are implemented for handling larger, structured combinations via nested AnyOf structures.

Features and Utilities

Methods inspired by Rust's Option and Result types:
- Creation utilities : AnyOf::new, AnyOf::new_left, AnyOf::new_both, etc.
- State checks: is_neither, is_left, is_both, etc.
- Transformations: map_left, map_right, swap, etc.
- Unwrapping: unwrap_left, unwrap_right, unwrap_both.
Flexible combinations :
- Operators like + to merge and manipulate values in AnyOf.
- Default value handling and state manipulation methods.

Use Cases

AnyOf and its related types simplify dynamic state management and are well-suited for:

Branching logic in functional programming.
Handling optional or partial data.
Implementing explicit and exhaustive handling of all potential states.
Minimizing boilerplate for complex decision-making.

Motivation

The project aims to enrich Rust's type system with expressive and flexible types for representing data combinations and states.

Unlike the Rust's Result type, Either has no semantic,
AnyOf<L, R> can be also be viewed as two options : (Option<L>, Option<R>) (a product type of sum type),

Status

The library is under active development and is not yet versioned as 1.*.*.
Feedback is welcome!

any_of 0.11.0