Crate libeither

Either struct

This is heavily influenced by the Either enum library. A struct version was required to be serializable to/from TOML, where enums are not valid. If you don't need struct specific serialization, you may want to use the enum Either instead.

Features

• serialization - Enable serialization via serde (on by default)
• unstable - Enable unstable options (nightly only, off by default)

Examples

let mut left: Either<&str, &str> = Either::new_left("lefty");

// Check for left or right
assert!(left.is_left());
assert!(!left.is_right());

// Check a reference to the contained value.
assert_eq!(left.left_ref()?, &"lefty");
assert!(left.right_ref().is_err());

// Mutate the contained value.
*(left.left_mut()?) = "left handed";
assert_eq!(left.left_ref()?, &"left handed");
assert!(left.right_mut().is_err());

// Flip the value
let flipped = left.flip()?;
assert_eq!(flipped.right_ref()?, &"left handed");
assert!(flipped.left_ref().is_err());

// Map a function over the left
let mapped_left: Either<usize, _> = left.map_left(|x| x.len())?;
assert_eq!(mapped_left.left_ref()?, &11);

// Chain execution
let new_left: Either<&str, &str> = Either::new_left("lefty");
let and_then_left: Either<usize, _> = new_left
    .and_then_left(|x| Either::new_left(x.len()))?
    .and_then_left(|x| Either::new_left(x * 10))?;
assert_eq!(and_then_left.left_ref()?, &50);

let new_right: Either<&str, &str> = Either::new_right("righty");
assert_eq!(new_right
    .and_then_left(|x: &str| Either::new_left(x.len()))?.right_ref()?, &"righty"
);

Structs

Either	A struct representing either a left value, or a right value.
Error	An error from the libeither library

Type Definitions

Result

A result that must include an Error