Anonymous Enums

Enum types with fully-generic variants.

This library defines enum types which are generic over from 2 (Enum2) to 16 (Enum16) type parameters. Each type parameter of a given enum type is the type of the single field of its respective variant of the same name (all variants are tuple structs with a single field).

```rust use std::collections::HashMap;

use anon_enum::Enum2;

/// Error type stating that a map does not contain a given key. struct ErrKeyNotFound;

/// Error type stating that an integer overflow occured during /// an arithmetic operation. struct ErrIntegerOverflow;

/// Maps a str to an integer of type i32 and returns the integer plus one. fn getandaddone( map: &HashMap<&str, i32>, key: &str, ) -> Result> { Ok(map .get(key) .okor(Enum2::T0(ErrKeyNotFound))? .checkedadd(1) .okor(Enum2::T1(ErrIntegerOverflow))?) }

fn main() { let mut fruit_count = HashMap::new();

fruit_count.insert("Lime", 5);
fruit_count.insert("Orange", i32::MAX);

matches!(get_and_add_one(&fruit_count, "Lime"), Ok(6));
matches!(
    get_and_add_one(&fruit_count, "Tangerine"),
    Err(Enum2::T0(ErrKeyNotFound))
);
matches!(
    get_and_add_one(&fruit_count, "Orange"),
    Err(Enum2::T1(ErrIntegerOverflow))
);

} ```

An enum of more than 16 variants may be expressed by setting the generic type T15 of Enum16 to an enum type:

rust // Enum of 18 variants. Enum16<T0, T1, ..., T14, Enum3<T15, T16, T17>>