#wrapper #array #vec #list #util


A rust wrapper built on top of rust vector implementation. Taste like Java Arraylist, and intuitive to use like Python list and JavaScript array.

3 releases

0.1.5 Jun 30, 2021
0.1.4 Jun 30, 2021
0.1.3 Jun 27, 2021
0.1.2 Jun 27, 2021
0.1.0 Jun 26, 2021

#712 in Data structures

46 downloads per month
Used in 2 crates (via simple_getopt)

MIT license

438 lines



arraylist -- An intutive rust vector wrapper built on top of rust vector implementation. Taste like Java Arraylist, and can be used like Python list functons and JavaScript array.


In the Cargo.toml file

arraylist = {git = "https://github.com/2teez/arraylist"}


arraylist = "0.1.3"

In the main.rs file

To Use

extern crate arraylist;

use arraylist::arl::ArrayList;


arraylist - is a rust wrapper built on the rust standard vector implementation. It makes it easier to work more intutively using vector as list or growable arrays in other languages like Java, JavaScript and others with little or no "fighting" with rust borrow checker; an ever present, stubborn but great friend coding in rust.

arraylist is NOT a rewrite of vec in rust, but rather a wrapping that provides safe, easier and possible interface while using "interior mutability" which rust language made available.

Using crate arraylist makes it possible to work with immutable values, objects etc, yet making several changes without having your code with "mut" keyword everywhere. Though, you might still have to use it in a few cases. But mostly you are working on immutable values.

The functions provided by arraylist crate, bears alot of resemblance with Java ArrayList methods. Even if you have not used java before, it feels intutive and hides some "headache" workings in rust-lang.


The code below is not possible just using vec in rust like so:

let vec = vec![1, 2, 3, 4, 5];
vec.push(6); // cannot borrow as mutable

With arraylist, it works like so, using immutable variable:

let arr = arraylist![1, 2, 3, 4];

// print out your arraylist like so:
arr.print(); // [1, 2, 3, 4, 5, 6]

However, to get the same result in vec, you must make your variable mutable.

You can also work with mutable variable using arraylist like so:

let mut arr = arraylist![];

arr.print(); // [1, 2, 3, 4, 5]
// or use
println!("{}", arr); // same result as above

Note that when function finish is called on the mutable 'object', you get back immutable one. You can chain them all up and get an immutable variable.

// you can create, add, and assign or print it all out
// like so

         .print();  // ["lagos", "enugu", "cairo"]
// or assign
let places = ArrayList::new().ad(..)..finish();

Try this one out using vanilla vec in rust

let al = arraylist![].add("bruno").add("b").add("🦀")

 // a for_each macro, takes an immutable variable and a closure
 // each of the string in the arraylist becomes a titled case
 for_each!(al, |a| {
     let mut upper = a.chars().collect::<Vec<_>>();
     upper[0] = upper[0].to_ascii_uppercase();
     upper.iter().fold(String::from(""), |mut a, b| {
 .print();  // ["Bruno", "B", "🦀", "ß", "བ\u{f7c}ད་ས\u{f90}ད་ལ"]

ArrayList Methods

arraylist uses a common name of function/method used in languages like Java, JavaScript, Python and the rest. So, the methods presented below are intutive to use. I intend to both present and demonstrate how each method can be used. But note that, each programmer's expression is limited by the amount of knowledge available to h(im|er).

Below are the list of the available methods in the crate ArrayList:

  1. add

    pub fn add(&mut self) -> &ArrayList<T>

    • Pushes a value into a mutable instance of either an empty or non-empty arraylist ArrayList. The length of the list is increased by 1.
       let al = ArrayList::new()
  2. add_all

    pub fn add_all(&self, collection: &[T])

    • Takes a slice refrence, and append each of it's elements to the end of the list. Using the extend function of the underlaying vec. The length of the list increased by the number of the elements in the slice. The capacity of the list is also adjusted accordingly.
    let al = arraylist![1, 2];
        al.add_all(&[3, 4, 5]);
        al.print(); // [1, 2, 3, 4, 5]
  3. add_all_at_index

    pub fn add_all_at_index(&self, idx: usize, collection: &[T])

    • This function takes two parameters; the starting index for the collection to be inserted. And the a slice refrence to be inserted. It pushes the values in the list to right as it adds values from the slice parameter. Note that the starting index MUST not be greater than the length of the list itself. If the starting index is greater than the length or size of the list, your code panics.
    let al = arraylist![1, 2, 3];
    al.add_all_at_index(1, &[4, 5, 6]);
    al.print(); // [1, 4, 5, 6, 2, 3]
  4. cap

    pub fn cap(&self) -> usize

    • Return the capacity of the list.
           ArrayList::start_with(&["coke", "fanta", "pepsi", "chapman"]).cap()
  5. clear

    pub fn clear(&self)

    • Clears: it is remove all the elements in the list.
        let al = arraylist![1, 2, 3];
        al.print(); // []
  6. clone

    pub fn clone(&self) -> ArrayList<T>

    • Returns a new different ArrayList instance, having the same elements. It is not a refrence. A change to the element made by clone does NOT in any way affect the other instance.
        let new_clone = al.clone();
        new_clone.print(); // [1, 3]
        al.print(); // []
  7. contains

    pub fn contains(&self, value: T) -> bool

    • Returns true if the list contains the value of the parameter.
        let players = arraylist!["Yekini", "Pele", "Ronaldo", "Messi"];
        println!("{}", players.contains("Yakubu")); // false
        println!("{}", players.contains("Ronaldo")); // true
  8. copy

    pub fn copy(&self) -> &ArrayList<T>

    • Returns a reference "copy" of the arraylist instance. Any change made one, reflect on the other. This is difference from the clone method. Note, you can make several copies of that instance.
            let new_copy = al.copy();
            new_copy.print(); // [1, 3, 0]
            al.print(); // [1, 3, 0]
  9. default

    pub fn default(&self) -> ArrayList<T>

    • Implements the Default traits for ArrayList. Returns a new arraylist instance with default values for each of it's elements.
           #[derive(Debug, Clone, PartialEq)]
           struct Person<'a> {
               name: &'a str,
               age: u32,
           let array = ArrayList::<Person>::default();
           array.print(); //   []
           array.push(Person {
               name: "boris",
               age: 23,
           array.print(); //  [Person { name: "boris", age: 23 }
  10. ensure_capacity

    pub fn ensure_capacity(size: usize) -> ArrayList<T>

    • Construts a new and empty ArrayList with a specified capacity.
        let na: ArrayList<u8> = ArrayList::ensure_capacity(10);
        println!("{}", na.cap()); // 10
  11. finish

    pub fn finish(&self) -> ArrayList<T>

    • Returns an immutable arraylist. Often called after the use of add function, which makes a mutable list and pushes it value into the list. finish is the function to call give immutable variable you wanted.
        let al = arraylist![]
                .finish();  // immutable
            al.print();     // ["Lagos", "Abuja"]
  12. for_each

    pub fn for_each(&self, f: fn(T))

    • It takes a closure and perform action in the closure on each of the elements in the list. But it does NOT change the element of the list.
        // square all odd numbers
        let nums = arraylist!(1, 2, 3, 4, 5);
        nums.for_each(|a| {
                match a % 2 != 0 {
                    true => a * a,
                    false => a,
        nums.print(); // [1, 2, 3, 4, 5]
        // if you want nums to change use macro `for_each!` instead
  13. from_slice

    pub fn from_slice(collection: &[T]) -> ArrayList<T>

    • Takes a reference to a slice of values and return an ArrayList of the same values.
        let fruits = ArrayList::from_slice(&["pineapple", "pear", "banana", "orange"]);
        fruits.print(); //  ["pineapple", "pear", "banana", "orange"]
  14. get

    pub fn get(&self, index: usize) -> Option<T>

    • get requires the index of the value wanted. It returns the value at the location wrapped in an option variant. If the index is greater than the length of the list, the operation panics. Else it returns the value in that index.
        let fruits = ArrayList::from_slice(&["pineapple", "pear", "banana", "orange"]);
        // println!("{}", fruits.get(31).unwrap()); // panics
        println!("{}", fruits.get(3).unwrap()); // orange
  15. index_in

    pub fn index_in(&self, value: usize) -> Option<T>

    works like get method.

  16. index_of

    pub fn index_of(&self, value: T) -> Option<usize>

    • Takes a parameter of the value and return the index where the value is located. index_of like a reverse of both get and index_in. If the value is not in the list, the operation panics on unwrap.
        //println!("{:?}", fruits.index_of("pine").unwrap()); // panics
        println!("{:?}", fruits.index_of("orange").unwrap()); // 3
  17. index_of_all

    pub fn index_of_all(&self, value: T) -> Vec<usize>

    • Takes a value as a paramater, and return vector of usize; Vec<T>, of all the indexes where the value could be found.
                "hello, world is luck to be loud"
        ); // [2, 3, 10, 16, 27]
  18. insert

    pub fn insert(&self, index: usize, value: T)

    • Given two paramaters; the index where the value to be inserted and the value to be inserted. This function, shift, the value in the index (or position) specified and "insert" the new value. Panics if index > length of the list.
            let places = arraylist![].add("Lagos").add("Abuja").finish();
            places.print();  // ["Lagos", "Abuja"]
            places.insert(1, "kumasi");
            places.print();  // ["Lagos", "kumasi", "Abuja"]
  19. is_empty

    pub fn is_empty(&self) -> bool

    Returns true if this list contains no elements, else it returns false.

        let al = arraylist!["yah", "yak", "kah"];
        println!("{}", al.is_empty()); // true
        println!("{}", arraylist![3, 5, 7, 9].is_empty()); // false
  20. len

    pub fn len(&self) -> usize

    • Returns the length of the list.
        let al = arraylist!["yah", "yak", "kah"];
        println!("{}", al.len()); // 3
        println!("{}", al.len()); // 0
  21. new

    pub fn new() -> ArrayList<T>

    • Constructs a new instance of arraylist with default values for the list type.
        let al = ArrayList::<String>::new();
        // or
        let al: ArrayList<String> = ArrayList::new();
  22. pop

    pub fn pop(&self) -> Option

    • Remove and return the last element in the list. Reducing the length and size of the list. The capacity of the list is not affected.
            let fruits = arraylist![
            println!("{}", fruits.pop().unwrap());
            println!("{}", fruits.pop().unwrap());
            fruits.print(); // ["orange", "pear", "pineapple", "tangerine"]
  23. print

    pub fn print(&self)

    • Prints out the elements in the list. It feels intutive to call print than to use the macro println! provideded in rust.
                let fruits = arraylist![
                fruits.print(); //["orange", "pear", "pineapple", "tangerine", "apple", "strawberry"]
  24. push

    pub fn push(&self, value: T) -> bool

    • Appends the specified element to the end of this list. But unlike add, it does NOT make the list mutable to do so. Though work like add, it can't be used in a "builder" design manner like method add. Returns a boolean.
                let al: ArrayList<i32> = ArrayList::new();
                al.print(); // [-34, 39, 25]
  25. push_on_index

    pub fn push_on_index(&self, index: usize, value: T)

    • Takes two parameters; the index and the value to insert in the list. It works exactly like insert method.
                let al = arraylist![1, 2, 3];
                al.push_on_index(1, 7);
                al.push_on_index(0, 9);
                al.print(); // [9, 1, 7, 2, 3]
  26. remove

    pub fn remove(&self, index: usize) -> T

    • It removes and return the element of the list specified by the supplied index as parameter. It also reduces the length of the list. Panics if the index > list length.
            println!("{}", al.remove(al.len() - 1)); // 3
            al.print();  // [9, 1, 7, 2]
            println!("{}", al.remove(2)); // 7
            al.print();  // [9, 1, 2]
  27. remove_if

    pub fn remove_if(&self, f: fn(T) -> bool)

    • It works like remove, but instead of index, it takes a closure as a parameter and it applies the closure to every element of the list.
            let al = arraylist![1, 2, 3, 4, 5, 6, 7, 8, 9];
                al.print(); // [1, 2, 3, 4, 5, 6, 7, 8, 9]
                al.remove_if(|a| a % 2 == 0);
                al.print(); // [1, 3, 5, 7, 9]
  28. replace

    pub fn replace(&self, index: usize, value: T)

    • It replaces the elements specified by the index provided, with the new value also specified by the function. It panics if the index is greater the list length.
            al.replace(0, 23);
            al.print();  // [23, 3, 5, 7, 9]
  29. size

    pub fn size(&self) -> usize

    • Returns the number of elements in the list. Works like method len.
            println!("{}", al.len()); // 5
  30. start_with

    pub fn start_with(collection: &[T]) -> ArrayList<T>

    • Construst and return an Arraylist ArrayList<T>, using the slice reference given from the parameter. The type of the arraylist is infered from the type of the slice given. The type can also be specified.
            let nums = ArrayList::start_with(&[1, 2, 3, 4, 5, 6]);
                nums.print(); // [1, 2, 3, 4, 5, 6]
  31. sub_list

    pub fn sub_list(&self, start: usize, stop: usize) -> Option<ArrayList>

    • Returns from this list all of the elements whose index is between start Index, inclusive, and to stop Index, exclusive. Panic if the to index is greater than the list length.
            let nums = ArrayList::start_with(&[1, 2, 3, 4, 5, 6]);
                nums.print(); // [1, 2, 3, 4, 5, 6]
                nums.sub_list(1, 4).unwrap().print(); // [2, 3, 4]
  32. to_vec

    pub fn to_vec(&self) -> Vec

    • Convert and returns a vector with the elements of the list. This is actually great, since rust vec has so many mehtod which this wrapper didn't implement. Converting the arraylist to vec makes it possible to use these so many methods from vector.


[] Carry out more test and benchmarks for more complex scenarios.

No runtime deps