unfold

A simple unfold implementation in Rust

unfold let you create an iterator that, staring from a given initial value, applies a given function to the current state, store the result for the next iteration, and return the current state.

Unfold defines an endless iterator: you must stop it by hand, like in the example.

Example

use unfold::Unfold;

// Create a vector containing the first 5 numbers from the Fibonacci
// series
let fibonacci_numbers: Vec<u64> = Unfold::new(|(a, b)| (b, a + b), (0, 1))
                                         .map(|(a, _)| a)
                                         .take(5)  //Unfold iterator never stops.
                                         .collect();
assert_eq!(vec![0, 1, 1, 2, 3], fibonacci_numbers);

lib.rs:

unfold

The unfold function takes as input a function f and an initial i value and returns a list defined as [i, f(i), f(f(i)), ...].

This library defines Unfold a struct that implements the unfold function as an endless iterator.

Quick Start

To use Unfold is quite simple. The user calls the new function providing a function as first argument and the initial value as second argument. An Unfold instance can be then used as any iterator, but don't forget: Unfold never ends, it must be stopped.

Here an example:

use unfold::Unfold;

// Create a vector containing the first 5 numbers from the Fibonacci
// series
let fibonacci_numbers: Vec<u64> = Unfold::new(|(a, b)| (b, a + b), (0, 1))
                                         .map(|(a, _)| a)
                                         .take(5)  //Unfold iterator never stops.
                                         .collect();
assert_eq!(vec![0, 1, 1, 2, 3], fibonacci_numbers);