Lowdash

liberocks/lowdash is a Lodash inspired utility library to manipulate array and object

⚠️ Disclaimer

This project is still in heavy development and not ready for production use.

🚀 Installation

cargo add lowdash

This library has no dependencies outside the Rust standard library.

📚 Documentation

You can find the generated documentation here

Utility functions for array:

• associate
• chunk
• compact
• count
• count_by
• count_values
• count_values_by
• drop
• drop_right
• drop_right_while
• drop_while
• earliest
• earliest_by
• fill
• filter
• filter_map
• filter_reject
• find
• find_duplicates
• find_duplicates_by
• find_index_of
• find_key
• find_key_by
• find_last_index_of
• find_or_else
• find_uniques
• find_uniques_by
• first
• first_or
• first_or_empty
• flat_map
• flatten
• foreach
• foreach_while
• group_by
• index_of
• interleave
• is_sorted
• is_sorted_by_key
• key_by
• last
• last_index_of
• last_or
• last_or_empty
• latest
• latest_by
• map
• max
• max_by
• min
• min_by
• nth
• partition_by
• reduce
• reduce_right
• reject
• reject_map
• repeat
• repeat_by
• replace
• replace_all
• reverse
• sample
• samples
• shuffle
• slice
• slice_to_map
• splice
• subset
• times
• uniq
• uniq_by = drop_by_index

Utility functions for string manipulation:

• camel_case
• capitalize
• char_length
• chunk_string
• ellipsis
• kebab_case
• pascal_case
• random_string
• snake_case
• substring
• words

Utility functions for math:

• nearest_power_of_two

camel_case

Converts a string to camelCase.

use lowdash::camel_case;

assert_eq!(camel_case("hello world"), "helloWorld");
assert_eq!(camel_case("foo-bar"), "fooBar");
assert_eq!(camel_case("lorem_ipsum"), "loremIpsum");
assert_eq!(camel_case("FooBarBazHello"), "fooBarBazHello");

capitalize

Capitalizes the first letter of the input string and converts the rest to lowercase.

use lowdash::capitalize;

assert_eq!(capitalize("hello"), "Hello");
assert_eq!(capitalize("WORLD"), "World");
assert_eq!(capitalize("rUsT"), "Rust");

char_length

Returns the length of a string in Unicode characters.

use lowdash::char_length;

assert_eq!(char_length("hello"), 5);
assert_eq!(char_length("🌍world"), 6);
assert_eq!(char_length("こんにちは"), 5);

chunk_string

Splits a string into chunks of specified size.

use lowdash::chunk_string;

let result = chunk_string("hello", 2);
assert_eq!(result, vec!["he", "ll", "o"]);

earliest_by

Find the earliest item in a collection based on a custom iteratee function.

use std::time::{SystemTime, Duration};
use lowdash::earliest_by;

let t1 = SystemTime::UNIX_EPOCH;
let t2 = t1 + Duration::new(60, 0);
let t3 = t1 + Duration::new(120, 0);
let times = vec![t2, t1, t3];
let earliest_time = earliest_by(&times, |&t| t);
assert_eq!(earliest_time, Some(t1));

#[derive(Debug, PartialEq, Clone)]
struct Event {
    name: String,
    timestamp: SystemTime,
}

let events = vec![
    Event {
        name: "Event1".to_string(),
        timestamp: t2,
    },
    Event {
        name: "Event2".to_string(),
        timestamp: t1,
    },
    Event {
        name: "Event3".to_string(),
        timestamp: t3,
    },
];

let earliest_event = earliest_by(&events, |e| e.timestamp);
assert_eq!(
    earliest_event,
    Some(Event {
        name: "Event2".to_string(),
        timestamp: t1,
    })
);

earliest

Find the earliest time in a collection.

use std::time::{SystemTime, Duration};
use lowdash::earliest;

let t1 = SystemTime::UNIX_EPOCH;
let t2 = t1 + Duration::new(60, 0);
let t3 = t1 + Duration::new(120, 0);
let times = vec![t2, t1, t3];
let earliest_time = earliest(&times);
assert_eq!(earliest_time, Some(t1));

ellipsis

Truncates a string and appends an ellipsis ("...") if it exceeds the specified length.

use lowdash::ellipsis;

let result = ellipsis("Hello, World!", 10);
assert_eq!(result, "Hello, ...");

let result = ellipsis("Short", 10);
assert_eq!(result, "Short");

let result = ellipsis("ExactLength", 11);
assert_eq!(result, "ExactLength");

let result = ellipsis("  Trimmed  ", 6);
assert_eq!(result, "Tri...");

let result = ellipsis("Hi", 2);
assert_eq!(result, "Hi");

find_duplicates_by

Find all duplicate elements in a collection based on a key generated by the iteratee function.

use lowdash::find_duplicates_by;
let numbers = vec![1, 2, 3, 4];
let result = find_duplicates_by(&numbers, |x| x % 2);
assert_eq!(result, vec![3, 4]); // Second occurrences of duplicated keys

use lowdash::find_duplicates_by;

#[derive(Debug, Clone, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 25 },
];

let result = find_duplicates_by(&people, |p| p.age);
assert_eq!(result, vec![
    Person { name: "Carol".to_string(), age: 25 },
]);

find_duplicates

Find all duplicate elements in a collection (elements that appear more than once).

use lowdash::find_duplicates;
let numbers = vec![1, 2, 2, 3, 3, 4];
let result = find_duplicates(&numbers);
assert_eq!(result, vec![2, 3]);

use lowdash::find_duplicates;
let words = vec!["apple", "banana", "apple", "cherry", "banana"];
let result = find_duplicates(&words);
assert_eq!(result, vec!["apple", "banana"]);

use lowdash::find_duplicates;

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
];

let result = find_duplicates(&people);
assert_eq!(result, vec![Person { name: "Alice".to_string(), age: 25 }]);

find_index_of

Find the first item in a collection that satisfies a predicate and return its index.

use lowdash::find_index_of;
let numbers = vec![1, 2, 3, 4, 5];
let predicate = |x: &i32| *x == 3;
let result = find_index_of(&numbers, predicate);
assert_eq!(result, Some((&3, 2)));

use lowdash::find_index_of;
let numbers = vec![10, 20, 30, 40];
let result = find_index_of(&numbers, |x| *x > 25);
assert_eq!(result, Some((&30, 2)));

use lowdash::find_index_of;

#[derive(Debug, PartialEq)]
struct Person {
   name: String,
   age: u32,
}

let people = vec![
   Person { name: "Alice".to_string(), age: 25 },
   Person { name: "Bob".to_string(), age: 30 },
   Person { name: "Carol".to_string(), age: 35 },
];

let result = find_index_of(&people, |p| p.age > 30);
assert_eq!(result, Some((&Person { name: "Carol".to_string(), age: 35 }, 2)));

find_key_by

Find the key in a map that satisfies a predicate based on both key and value.

use lowdash::find_key_by;
let mut map = std::collections::HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
let result = find_key_by(&map, |k, v| *k == "b" && *v == 2);
assert_eq!(result, Some(&"b"));

use lowdash::find_key_by;
let mut map = std::collections::HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
let result = find_key_by(&map, |_, v| *v > 2);
assert_eq!(result, Some(&"c"));

find_key

Find the key in a map that corresponds to a given value.

use lowdash::find_key;
let mut map = std::collections::HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
let result = find_key(&map, 2);
assert_eq!(result, Some(&"b"));

use lowdash::find_key;
let mut map = std::collections::HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
let result = find_key(&map, 4);
assert_eq!(result, None);

use lowdash::find_key;

#[derive(Debug, PartialEq, Eq, Hash)]
struct Person {
   name: String,
   age: u32,
}

let mut map = std::collections::HashMap::new();
map.insert(Person { name: "Alice".to_string(), age: 25 }, "Engineer");
map.insert(Person { name: "Bob".to_string(), age: 30 }, "Manager");
map.insert(Person { name: "Carol".to_string(), age: 35 }, "Director");

let result = find_key(&map, "Manager");
assert_eq!(result, Some(&Person { name: "Bob".to_string(), age: 30 }));

find_last_index_of

Find the last item in a collection that satisfies a predicate and return its index.

use lowdash::find_last_index_of;
let numbers = vec![1, 2, 3, 4, 5, 3];
let predicate = |x: &i32| *x == 3;
let result = find_last_index_of(&numbers, predicate);
assert_eq!(result, Some((&3, 5)));

use lowdash::find_last_index_of;
let numbers = vec![10, 20, 30, 40, 30];
let result = find_last_index_of(&numbers, |x| *x > 25);
assert_eq!(result, Some((&30, 4)));

use lowdash::find_last_index_of;

#[derive(Debug, PartialEq)]
struct Person {
   name: String,
   age: u32,
}

let people = vec![
   Person { name: "Alice".to_string(), age: 25 },
   Person { name: "Bob".to_string(), age: 30 },
   Person { name: "Carol".to_string(), age: 35 },
   Person { name: "Dave".to_string(), age: 35 },
];

let result = find_last_index_of(&people, |p| p.age > 30);
assert_eq!(result, Some((&Person { name: "Dave".to_string(), age: 35 }, 3)));

find_or_else

Find the first item in a collection that satisfies a predicate.

use lowdash::find_or_else;
let numbers = vec![1, 2, 3, 4, 5];
let predicate = |x: &i32| *x == 3;
let result = find_or_else(&numbers, &0, predicate);
assert_eq!(result, &3);

use lowdash::find_or_else;
let numbers = vec![10, 20, 30, 40];
let result = find_or_else(&numbers, &0, |x| *x > 50);
assert_eq!(result, &0);

use lowdash::find_or_else;

#[derive(Debug, PartialEq)]
struct Person {
   name: String,
   age: u32,
}

let people = vec![
   Person { name: "Alice".to_string(), age: 25 },
   Person { name: "Bob".to_string(), age: 30 },
   Person { name: "Carol".to_string(), age: 35 },
];

let fallback = Person { name: "Unknown".to_string(), age: 0 };
let result = find_or_else(&people, &fallback, |p| p.age > 30);
assert_eq!(result, &Person { name: "Carol".to_string(), age: 35 });

find_uniques

Find all unique elements in a collection (elements that appear exactly once).

use lowdash::find_uniques;
let numbers = vec![1, 2, 2, 3, 3, 4];
let result = find_uniques(&numbers);
assert_eq!(result, vec![1, 4]);

use lowdash::find_uniques;
let words = vec!["apple", "banana", "apple", "cherry"];
let result = find_uniques(&words);
assert_eq!(result, vec!["banana", "cherry"]);

use lowdash::find_uniques;

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
];

let result = find_uniques(&people);
assert_eq!(result, vec![Person { name: "Bob".to_string(), age: 30 }]);

find_uniques_by

Find all unique elements in a collection based on a key generated by the iteratee function.

use lowdash::find_uniques_by;
let numbers = vec![1, 2, 3, 4];
let result = find_uniques_by(&numbers, |x| x % 2);  // Group by even/odd
assert_eq!(result, vec![]);  // No unique remainders

use lowdash::find_uniques_by;

#[derive(Debug, Clone, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 25 },
];

let result = find_uniques_by(&people, |p| p.age);
assert_eq!(result, vec![Person { name: "Bob".to_string(), age: 30 }]);

find

Find the first item in a collection that satisfies a predicate.

use lowdash::find;
let numbers = vec![1, 2, 3, 4, 5];
let predicate = |x: &i32| *x == 3;
let result = find(&numbers, predicate);
assert_eq!(result, Some(&3));

use lowdash::find;
let numbers = vec![10, 20, 30, 40];
let result = find(&numbers, |x| *x > 25);
assert_eq!(result, Some(&30));

use lowdash::find;

#[derive(Debug, PartialEq)]
struct Person {
   name: String,
   age: u32,
}

let people = vec![
   Person { name: "Alice".to_string(), age: 25 },
   Person { name: "Bob".to_string(), age: 30 },
   Person { name: "Carol".to_string(), age: 35 },
];

let result = find(&people, |p| p.age > 30);
assert_eq!(result, Some(&Person { name: "Carol".to_string(), age: 35 }));

first_or_empty

Returns the first item from the collection.

use lowdash::first_or_empty;

let numbers = vec![1, 2, 3];
let first_num = first_or_empty(&numbers);
assert_eq!(first_num, 1);

let empty: Vec<i32> = vec![];
let first_num = first_or_empty(&empty);
assert_eq!(first_num, 0); // i32::default() is 0

use lowdash::first_or_empty;

#[derive(Debug, PartialEq, Clone, Default)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
];

let first_person = first_or_empty(&people);
assert_eq!(first_person, Person { name: "Alice".to_string(), age: 25 });

let empty_people: Vec<Person> = vec![];
let first_person = first_or_empty(&empty_people);
assert_eq!(first_person, Person::default());

first_or

Returns the first item from the collection.

use lowdash::first_or;

let numbers = vec![1, 2, 3];
let first_num = first_or(&numbers, 10);
assert_eq!(first_num, 1);

let empty: Vec<i32> = vec![];
let first_num = first_or(&empty, 10);
assert_eq!(first_num, 10);

use lowdash::first_or;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
];

let first_person = first_or(&people, Person { name: "Default".to_string(), age: 0 });
assert_eq!(first_person, Person { name: "Alice".to_string(), age: 25 });

let empty_people: Vec<Person> = vec![];
let first_person = first_or(&empty_people, Person { name: "Default".to_string(), age: 0 });
assert_eq!(first_person, Person { name: "Default".to_string(), age: 0 });

first

Returns the first item from the collection.

use lowdash::first;

let numbers = vec![1, 2, 3];
let (first_num, exists) = first(&numbers);
assert_eq!(first_num, 1);
assert!(exists);

let empty: Vec<i32> = vec![];
let (first_num, exists) = first(&empty);
assert_eq!(first_num, 0); // i32::default() is 0
assert!(!exists);

index_of

Finds the position of the first occurrence of an element in a collection.

use lowdash::index_of;
let collection = vec![1, 2, 3, 4, 5];
let index = index_of(&collection, 3);
assert_eq!(index, 2);

use lowdash::index_of;
let collection = vec!["apple", "banana", "cherry"];
let index = index_of(&collection, "banana");
assert_eq!(index, 1);

use lowdash::index_of;
let collection = vec![1, 2, 3, 4, 5];
let index = index_of(&collection, 6);
assert_eq!(index, -1);

kebab_case

Converts a string to kebab-case.

use lowdash::kebab_case;

assert_eq!(kebab_case("hello world"), "hello-world");
assert_eq!(kebab_case("foo-bar"), "foo-bar");
assert_eq!(kebab_case("lorem_ipsum"), "lorem-ipsum");
assert_eq!(kebab_case("FooBarBazHello"), "foo-bar-baz-hello");
assert_eq!(kebab_case("helloWorld"), "hello-world");

last_index_of

Finds the position of the last occurrence of an element in a collection.

use lowdash::last_index_of;
let collection = vec![1, 2, 3, 2, 1];
let index = last_index_of(&collection, 2);
assert_eq!(index, 3);

use lowdash::last_index_of;
let collection = vec!["apple", "banana", "cherry", "banana"];
let index = last_index_of(&collection, "banana");
assert_eq!(index, 3);

use lowdash::last_index_of;
let collection = vec![1, 2, 3, 4, 5];
let index = last_index_of(&collection, 6);
assert_eq!(index, -1);

last_or_empty

Returns the last item from the collection.

use lowdash::last_or_empty;

let numbers = vec![1, 2, 3];
let last_num = last_or_empty(&numbers);
assert_eq!(last_num, 3);

let empty: Vec<i32> = vec![];
let last_num = last_or_empty(&empty);
assert_eq!(last_num, 0); // i32::default() is 0

use lowdash::last_or_empty;

#[derive(Debug, PartialEq, Clone, Default)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
];

let last_person = last_or_empty(&people);
assert_eq!(last_person, Person { name: "Bob".to_string(), age: 30 });

let empty_people: Vec<Person> = vec![];
let last_person = last_or_empty(&empty_people);
assert_eq!(last_person, Person::default());

last_or

Returns the last item from the collection.

use lowdash::last_or;

let numbers = vec![1, 2, 3];
let last_num = last_or(&numbers, 10);
assert_eq!(last_num, 3);

let empty: Vec<i32> = vec![];
let last_num = last_or(&empty, 10);
assert_eq!(last_num, 10);

last

Returns the last item from the collection.

use lowdash::last;

let numbers = vec![1, 2, 3];
let (last_num, exists) = last(&numbers);
assert_eq!(last_num, 3);
assert!(exists);

let empty: Vec<i32> = vec![];
let (last_num, exists) = last(&empty);
assert_eq!(last_num, 0); // i32::default() is 0
assert!(!exists);

use lowdash::last;

#[derive(Debug, PartialEq, Clone, Default)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
];

let (last_person, exists) = last(&people);
assert_eq!(last_person, Person { name: "Bob".to_string(), age: 30 });
assert!(exists);

let empty_people: Vec<Person> = vec![];
let (last_person, exists) = last(&empty_people);
assert_eq!(last_person, Person::default());
assert!(!exists);

latest_by

Returns the item from the collection for which the iteratee returns the latest SystemTime.

use std::time::{SystemTime, Duration};
use lowdash::latest_by;

#[derive(Debug, PartialEq, Clone)]
struct Record {
    id: u32,
    timestamp: SystemTime,
}

impl Default for Record {
    fn default() -> Self {
        Record {
            id: 0,
            timestamp: SystemTime::UNIX_EPOCH,
        }
    }
}

let records = vec![
    Record {
        id: 1,
        timestamp: SystemTime::UNIX_EPOCH + Duration::new(100, 0),
    },
    Record {
        id: 2,
        timestamp: SystemTime::UNIX_EPOCH + Duration::new(200, 0),
    },
    Record {
        id: 3,
        timestamp: SystemTime::UNIX_EPOCH + Duration::new(150, 0),
    },
];

let latest_record = latest_by(&records, |r| r.timestamp);
assert_eq!(latest_record.id, 2);

latest

Returns the latest SystemTime from the provided arguments.

use std::time::{SystemTime, Duration};
use lowdash::latest;

let now = SystemTime::now();
let later = now + Duration::new(10, 0);
let latest_time = latest(&[now, later]);
assert_eq!(latest_time, later);

max_by

Find the maximum element in a collection based on a custom comparison function.

use lowdash::max_by;

#[derive(Debug, PartialEq, Eq, Clone)]
struct Person {
    age: u32,
    name: String,
}

let people = vec![
    Person { age: 25, name: "Alice".to_string() },
    Person { age: 30, name: "Bob".to_string() },
    Person { age: 20, name: "Carol".to_string() },
];

let result = max_by(&people, |a, b| a.age > b.age);
assert_eq!(
    result,
    Some(Person { age: 30, name: "Bob".to_string() })
);

max

Find the maximum element in a collection.

use lowdash::max;
let numbers = vec![5, 3, 8, 1, 4];
let result = max(&numbers);
assert_eq!(result, Some(8));

use lowdash::max;
let strings = vec!["apple", "banana", "cherry"];
let result = max(&strings);
assert_eq!(result, Some("cherry"));

use lowdash::max;

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Cia".to_string(), age: 20 },
];

let result = max(&people);
assert_eq!(
    result,
    Some(Person { name: "Cia".to_string(), age: 20 })
);

use lowdash::max;
let collection = vec![3.14, 2.71, -1.0, 0.0];
let result = max(&collection);
assert_eq!(result, Some(3.14));

min_by

Find the minimum element in a collection based on a custom comparison function.

use lowdash::min_by;

let numbers = vec![5, 3, 8, 1, 4];
let min = min_by(&numbers, |a, b| a < b);
assert_eq!(min, Some(1));

let strings = vec!["apple", "banana", "cherry"];
let min = min_by(&strings, |a, b| a.len() < b.len());
assert_eq!(min, Some("apple"));

let empty: Vec<i32> = vec![];
let min = min_by(&empty, |a, b| a < b);
assert_eq!(min, None);

min

Find the minimum element in a collection.

use lowdash::min;
let numbers = vec![5, 3, 8, 1, 4];
let result = min(&numbers);
assert_eq!(result, Some(1));

use lowdash::min;
let strings = vec!["apple", "banana", "cherry"];
let result = min(&strings);
assert_eq!(result, Some("apple"));

use lowdash::min;

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 20 },
];

let result = min(&people);
assert_eq!(
    result,
    Some(Person { name: "Alice".to_string(), age: 25 })
);

use lowdash::min;
let collection = vec![3.14, 2.71, -1.0, 0.0];
let result = min(&collection);
assert_eq!(result, Some(-1.0));

nearest_power_of_two

Calculates the smallest power of two greater than or equal to the given capacity.

use lowdash::nearest_power_of_two;

assert_eq!(nearest_power_of_two(0), 1);
assert_eq!(nearest_power_of_two(1), 1);
assert_eq!(nearest_power_of_two(5), 8);
assert_eq!(nearest_power_of_two(16), 16);
assert_eq!(nearest_power_of_two(17), 32);

nth

Returns the nth element from the collection.

use lowdash::nth;

let numbers = vec![1, 2, 3, 4, 5];
let result = nth(&numbers, 2);
assert_eq!(result.unwrap(), &3);

let result = nth(&numbers, -2);
assert_eq!(result.unwrap(), &4);

let result = nth(&numbers, 10);
assert!(result.is_err());

pascal_case

Converts a string to PascalCase.

use lowdash::pascal_case;

assert_eq!(pascal_case("hello world"), "HelloWorld");
assert_eq!(pascal_case("foo-bar"), "FooBar");
assert_eq!(pascal_case("lorem_ipsum"), "LoremIpsum");

random_string

Generates a random string of a specified size using the provided charset.

use lowdash::common::ALPHANUMERIC_CHARSET;
use lowdash::random_string;

let charset = ALPHANUMERIC_CHARSET;
let random_str = random_string(10, charset);
assert_eq!(random_str.len(), 10);
for c in random_str.chars() {
    assert!(charset.contains(&c));
}

sample

Returns a pseudo-random element from the collection.

use lowdash::sample;

let numbers = vec![1, 2, 3, 4, 5];
let result = sample(&numbers);
assert!(numbers.contains(&result));

let empty: Vec<i32> = vec![];
let result = sample(&empty);
assert_eq!(result, 0); // i32::default()

samples

Returns a slice of pseudo-randomly selected elements from the collection.

use lowdash::samples;

let numbers = vec![1, 2, 3, 4, 5];
let result = samples(&numbers, 3);
assert_eq!(result.len(), 3);
assert!(result.iter().all(|x| numbers.contains(x)));

snake_case

Converts a string to snake_case.

use lowdash::snake_case;

assert_eq!(snake_case("hello world"), "hello_world");
assert_eq!(snake_case("foo-bar"), "foo_bar");
assert_eq!(snake_case("lorem_ipsum"), "lorem_ipsum");
assert_eq!(snake_case("FooBarBazHello"), "foo_bar_baz_hello");
assert_eq!(snake_case("fooBarBazHello"), "foo_bar_baz_hello");

substring

Extracts a substring from the given string based on the specified offset and length.

use lowdash::substring;

let s = String::from("Hello, World!");
assert_eq!(substring(&s, 7, 5), "World");

let s = String::from("Hello, World!");
assert_eq!(substring(&s, -6, 5), "World");

let s = String::from("Hello, World!");
assert_eq!(substring(&s, 100, 5), "");

let s = String::from("Hello\x00World!");
assert_eq!(substring(&s, 0, 10), "HelloWorld");

words

Splits a string into words based on casing, digits, and separators.

use lowdash::words;

let result = words("Int8Value");
assert_eq!(result, vec!["Int", "8", "Value"]);

let result = words("hello_world");
assert_eq!(result, vec!["hello", "world"]);

let result = words("fooBarBazHello");
assert_eq!(result, vec!["foo", "Bar", "Baz", "Hello"]);

reject

Reject items from a collection that satisfy a predicate.

use lowdash::reject;
let numbers = vec![1, 2, 3, 4, 5];
let result = reject(&numbers, |x, _| *x % 2 == 0);
assert_eq!(result, vec![&1, &3, &5]);

filter

Filter items from a collection that satisfy a predicate.

use lowdash::filter;
let numbers = vec![1, 2, 3, 4, 5];
let result = filter(&numbers, |x, _| *x % 2 == 0);
assert_eq!(result, vec![&2, &4]);

use lowdash::filter;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let result = filter(&people, |p, _| p.age > 30);
assert_eq!(result, vec![&people[2]]);

map

Apply a function to each item in a collection, producing a new collection of results.

use lowdash::map;
let numbers = vec![1, 2, 3, 4, 5];
let result = map(&numbers, |x, _| x * 2);
assert_eq!(result, vec![2, 4, 6, 8, 10]);

use lowdash::map;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let names: Vec<String> = map(&people, |p, _| p.name.clone());
assert_eq!(names, vec!["Alice", "Bob", "Carol"]);

filter_map

Apply a function to each item in a collection, filtering and transforming items based on a callback.

use lowdash::filter_map;
let numbers = vec![1, 2, 3, 4, 5];
// Double even numbers
let result = filter_map(&numbers, |x, _| {
    if *x % 2 == 0 {
        (x * 2, true)
    } else {
        (0, false)
    }
});
assert_eq!(result, vec![4, 8]);

use lowdash::filter_map;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

// Extract names of people older than 28
let names: Vec<String> = filter_map(&people, |p, _| {
    if p.age > 28 {
        (p.name.clone(), true)
    } else {
        (String::new(), false)
    }
});
assert_eq!(names, vec!["Bob".to_string(), "Carol".to_string()]);

flat_map

Apply a function to each item in a collection, flattening the results based on a callback.

use lowdash::flat_map;
let numbers = vec![1, 2, 3];
// For each number, generate a vector containing the number and its double
let result = flat_map(&numbers, |x, _| vec![*x, *x * 2]);
assert_eq!(result, vec![1, 2, 2, 4, 3, 6]);

use lowdash::flat_map;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    hobbies: Vec<String>,
}

let people = vec![
    Person {
        name: "Alice".to_string(),
        hobbies: vec!["Reading".to_string(), "Cycling".to_string()],
    },
    Person {
        name: "Bob".to_string(),
        hobbies: vec!["Cooking".to_string()],
    },
];

// Extract all hobbies from the list of people
let all_hobbies: Vec<String> = flat_map(&people, |person, _| person.hobbies.clone());
assert_eq!(
    all_hobbies,
    vec![
        "Reading".to_string(),
        "Cycling".to_string(),
        "Cooking".to_string()
    ]
);

reduce

Apply a function to each item in a collection, accumulating a single result.

use lowdash::reduce;
let numbers = vec![1, 2, 3, 4, 5];
// Sum of all numbers
let sum = reduce(&numbers, |acc, x, _| acc + x, 0);
assert_eq!(sum, 15);

use lowdash::reduce;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

// Concatenate all names
let all_names = reduce(&people, |acc, person, _| format!("{} {}", acc, person.name), String::new());
assert_eq!(all_names.trim(), "Alice Bob Carol");

reduce_right

Apply a function to each item in a collection, accumulating a single result from right to left.

use lowdash::reduce_right;
let numbers = vec![1, 2, 3, 4, 5];
// Sum of all numbers using reduce_right
let sum = reduce_right(&numbers, |acc, x, _| acc + x, 0);
assert_eq!(sum, 15);

use lowdash::reduce_right;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

// Concatenate all names in reverse order
let all_names = reduce_right(&people, |acc, person, _| {
    if acc.is_empty() {
        person.name.clone()
    } else {
        format!("{} {}", acc, person.name)
    }
}, String::new());
assert_eq!(all_names, "Carol Bob Alice");

foreach

Execute a function on each item in a collection.

use lowdash::foreach;
let numbers = vec![1, 2, 3, 4, 5];
let mut sum = 0;
foreach(&numbers, |x, _| sum += x);
assert_eq!(sum, 15);

use lowdash::foreach;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let mut names = Vec::new();
foreach(&people, |p, _| names.push(p.name.clone()));
assert_eq!(names, vec!["Alice", "Bob", "Carol"]);

foreach_while

Execute a function on each item in a collection until the iteratee returns false.

use lowdash::foreach_while;
let numbers = vec![1, 2, 3, 4, 5];
let mut sum = 0;
foreach_while(&numbers, |x, _| {
    sum += x;
    true
});
assert_eq!(sum, 15);

use lowdash::foreach_while;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let mut names = Vec::new();
foreach_while(&people, |p, _| {
    names.push(p.name.clone());
    true
});
assert_eq!(names, vec!["Alice", "Bob", "Carol"]);

use lowdash::foreach_while;

let numbers = vec![10, 20, 30, 40, 50];
let mut collected = Vec::new();
foreach_while(&numbers, |x, index| {
    if *x < 35 {
        collected.push((*x, index));
        true
    } else {
        false
    }
});
assert_eq!(collected, vec![(10, 0), (20, 1), (30, 2)]);

times

Generates a collection by invoking the provided function iteratee a specified number of times.

use lowdash::times;
let result = times(5, |i| i * 2);
assert_eq!(result, vec![0, 2, 4, 6, 8]);

use lowdash::times;
let result = times(3, |i| format!("Item {}", i));
assert_eq!(result, vec!["Item 0", "Item 1", "Item 2"]);

uniq

Remove duplicate elements from a collection, preserving the order of their first occurrence.

use lowdash::uniq;
let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let unique_numbers = uniq(&numbers);
assert_eq!(unique_numbers, vec![1, 2, 3, 4, 5]);

use lowdash::uniq;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let unique_people = uniq(&people);
assert_eq!(unique_people, vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
]);

uniq_by

Remove duplicate elements from a collection based on a key extracted by a provided function, preserving the order of their first occurrence.

use lowdash::uniq_by;
let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let unique_numbers = uniq_by(&numbers, |x| *x);
assert_eq!(unique_numbers, vec![1, 2, 3, 4, 5]);

use lowdash::uniq_by;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let unique_people = uniq_by(&people, |p| p.name.clone());
assert_eq!(unique_people, vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
]);

group_by

Group elements of a collection based on a key extracted by a provided function, preserving the order of their first occurrence.

use lowdash::group_by;

let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let grouped = group_by(&numbers, |x| *x % 2 == 0);

assert_eq!(grouped.get(&false), Some(&vec![1, 3, 3, 5]));
assert_eq!(grouped.get(&true), Some(&vec![2, 2, 4]));

use lowdash::group_by;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 25 },
];

let grouped = group_by(&people, |p| p.age);

assert_eq!(grouped.get(&25), Some(&vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 25 },
]));
assert_eq!(grouped.get(&30), Some(&vec![
    Person { name: "Bob".to_string(), age: 30 },
]));

chunk

Divide a collection into smaller chunks of a specified size, preserving the order of elements.

use lowdash::chunk;

let numbers = vec![1, 2, 3, 4, 5, 6, 7];
let chunks = chunk(&numbers, 3);
assert_eq!(
    chunks,
    vec![vec![1, 2, 3], vec![4, 5, 6], vec![7]]
);

use lowdash::chunk;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
    Person { name: "Dave".to_string(), age: 40 },
];

let chunks = chunk(&people, 2);
assert_eq!(
    chunks,
    vec![
        vec![
            Person { name: "Alice".to_string(), age: 25 },
            Person { name: "Bob".to_string(), age: 30 },
        ],
        vec![
            Person { name: "Carol".to_string(), age: 35 },
            Person { name: "Dave".to_string(), age: 40 },
        ],
    ]
);

partition_by

Divide a collection into partitions based on a key extracted by a provided function, preserving the order of elements and the order of partitions as they first appear.

use lowdash::partition_by;

let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let partitions = partition_by(&numbers, |x| *x);
assert_eq!(
    partitions,
    vec![vec![1], vec![2, 2], vec![3, 3], vec![4], vec![5]]
);

use lowdash::partition_by;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let partitions = partition_by(&people, |p| p.age);
assert_eq!(
    partitions,
    vec![
        vec![
            Person { name: "Alice".to_string(), age: 25 },
            Person { name: "Alice".to_string(), age: 25 },
        ],
        vec![
            Person { name: "Bob".to_string(), age: 30 },
        ],
        vec![
            Person { name: "Carol".to_string(), age: 35 },
        ],
    ]
);

flatten

Flatten a collection of slices into a single vector, preserving the order of elements.

use lowdash::flatten;

let nested = vec![vec![1, 2], vec![3, 4], vec![5]];
let flat = flatten(&nested);
assert_eq!(flat, vec![1, 2, 3, 4, 5]);

use lowdash::flatten;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people_groups = vec![
    vec![
        Person { name: "Alice".to_string(), age: 25 },
        Person { name: "Bob".to_string(), age: 30 },
    ],
    vec![
        Person { name: "Carol".to_string(), age: 35 },
        Person { name: "Dave".to_string(), age: 40 },
    ],
];

let flat_people = flatten(&people_groups);
assert_eq!(
    flat_people,
    vec![
        Person { name: "Alice".to_string(), age: 25 },
        Person { name: "Bob".to_string(), age: 30 },
        Person { name: "Carol".to_string(), age: 35 },
        Person { name: "Dave".to_string(), age: 40 },
    ]
);

interleave

Interleave multiple collections into a single vector, preserving the order of elements.

use lowdash::interleave;

let a = vec![1, 2, 3];
let b = vec![4, 5, 6, 7];
let c = vec![8, 9];

let result = interleave(&[&a[..], &b[..], &c[..]]);
assert_eq!(result, vec![1, 4, 8, 2, 5, 9, 3, 6, 7]);

use lowdash::interleave;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let group1 = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
];

let group2 = vec![
    Person { name: "Carol".to_string(), age: 35 },
];

let group3 = vec![
    Person { name: "Dave".to_string(), age: 40 },
    Person { name: "Eve".to_string(), age: 45 },
    Person { name: "Frank".to_string(), age: 50 },
];

let interleaved = interleave(&[&group1[..], &group2[..], &group3[..]]);
assert_eq!(
    interleaved,
    vec![
        Person { name: "Alice".to_string(), age: 25 },
        Person { name: "Carol".to_string(), age: 35 },
        Person { name: "Dave".to_string(), age: 40 },
        Person { name: "Bob".to_string(), age: 30 },
        Person { name: "Eve".to_string(), age: 45 },
        Person { name: "Frank".to_string(), age: 50 },
    ]
);

shuffle

Shuffle a collection, returning a new vector with the elements in random order.

use lowdash::shuffle;

let numbers = vec![1, 2, 3, 4, 5];
let shuffled = shuffle(&numbers);
assert_eq!(shuffled.len(), numbers.len());
assert!(shuffled.contains(&1));
assert!(shuffled.contains(&2));
assert!(shuffled.contains(&3));
assert!(shuffled.contains(&4));
assert!(shuffled.contains(&5));

reverse

Reverse a collection, returning a new vector with the elements in reverse order.

use lowdash::reverse;

let numbers = vec![1, 2, 3, 4, 5];
let reversed = reverse(&numbers);
assert_eq!(reversed, vec![5, 4, 3, 2, 1]);

use lowdash::reverse;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let reversed_people = reverse(&people);
assert_eq!(reversed_people, vec![
    Person { name: "Carol".to_string(), age: 35 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
]);

fill

Fill a collection with a specified value, returning a new vector with all elements set to the initial value.

use lowdash::fill;

let numbers = vec![1, 2, 3, 4, 5];
let filled = fill(&numbers, 0);
assert_eq!(filled, vec![0, 0, 0, 0, 0]);

use lowdash::fill;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

let filled_people = fill(&people, Person { name: "Dave".to_string(), age: 40 });
assert_eq!(
    filled_people,
    vec![
        Person { name: "Dave".to_string(), age: 40 },
        Person { name: "Dave".to_string(), age: 40 },
        Person { name: "Dave".to_string(), age: 40 },
    ]
);

repeat

Fill a collection with a specified value, returning a new vector with all elements set to the initial value.

use lowdash::repeat;

let filled = repeat(5, 0);
assert_eq!(filled, vec![0, 0, 0, 0, 0]);

use lowdash::repeat;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let filled_people = repeat(3, Person { name: "Dave".to_string(), age: 40 });
assert_eq!(
    filled_people,
    vec![
        Person { name: "Dave".to_string(), age: 40 },
        Person { name: "Dave".to_string(), age: 40 },
        Person { name: "Dave".to_string(), age: 40 },
    ]
);

repeat_by

Repeat a specified value count times by applying a predicate function to each index, returning a new vector with the generated elements.

use lowdash::repeat_by;

let filled = repeat_by(5, |i| i * 2);
assert_eq!(filled, vec![0, 2, 4, 6, 8]);

use lowdash::repeat_by;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let filled_people = repeat_by(3, |i| Person {
    name: format!("Person {}", i + 1),
    age: 20 + i as u32 * 5,
});
assert_eq!(
    filled_people,
    vec![
        Person { name: "Person 1".to_string(), age: 20 },
        Person { name: "Person 2".to_string(), age: 25 },
        Person { name: "Person 3".to_string(), age: 30 },
    ]
);

key_by

Creates a HashMap by mapping each element in a collection to a key using an iteratee function.

use lowdash::key_by;
use std::collections::HashMap;

let numbers = vec![1, 2, 3, 4, 5];
let map = key_by(&numbers, |&x| x % 2);
let mut expected = HashMap::new();
expected.insert(1, 5); // Last odd number
expected.insert(0, 4); // Last even number
assert_eq!(map, expected);

use lowdash::key_by;
use std::collections::HashMap;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Charlie".to_string(), age: 35 },
];

let map = key_by(&people, |person| person.name.clone());
let mut expected = HashMap::new();
expected.insert("Alice".to_string(), people[0].clone());
expected.insert("Bob".to_string(), people[1].clone());
expected.insert("Charlie".to_string(), people[2].clone());
assert_eq!(map, expected);

use lowdash::key_by;
use std::collections::HashMap;

let strings = vec!["apple", "banana", "apricot", "blueberry"];
let map = key_by(&strings, |s| s.chars().next().unwrap());
let mut expected = HashMap::new();
expected.insert('a', "apricot");
expected.insert('b', "blueberry");
assert_eq!(map, expected);

associate

Creates a HashMap by transforming each element in a collection into a key-value pair using a provided function.

use lowdash::associate;
use std::collections::HashMap;

let numbers = vec![1, 2, 3, 4, 5];
let map = associate(&numbers, |&x| (x, x * x));
let mut expected = HashMap::new();
expected.insert(1, 1);
expected.insert(2, 4);
expected.insert(3, 9);
expected.insert(4, 16);
expected.insert(5, 25);
assert_eq!(map, expected);

use lowdash::associate;
use std::collections::HashMap;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Charlie".to_string(), age: 35 },
];

let map = associate(&people, |person| (person.name.clone(), person.age));
let mut expected = HashMap::new();
expected.insert("Alice".to_string(), 25);
expected.insert("Bob".to_string(), 30);
expected.insert("Charlie".to_string(), 35);
assert_eq!(map, expected);

use lowdash::associate;
use std::collections::HashMap;

let strings = vec!["apple", "banana", "apricot", "blueberry"];
let map = associate(&strings, |s| (s.chars().next().unwrap(), s.len()));
let mut expected = HashMap::new();
expected.insert('a', 7); // "apricot" has 7 characters
expected.insert('b', 9); // "blueberry" has 9 characters
assert_eq!(map, expected);

slice_to_map

Transforms a slice of items into a HashMap by applying a provided function to each item.

use lowdash::slice_to_map;
use std::collections::HashMap;

let numbers = vec![1, 2, 3, 4, 5];
let map = slice_to_map(&numbers, |&x| (x, x * x));
let mut expected = HashMap::new();
expected.insert(1, 1);
expected.insert(2, 4);
expected.insert(3, 9);
expected.insert(4, 16);
expected.insert(5, 25);
assert_eq!(map, expected);

use lowdash::slice_to_map;
use std::collections::HashMap;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Charlie".to_string(), age: 35 },
];

let map = slice_to_map(&people, |person| (person.name.clone(), person.age));
let mut expected = HashMap::new();
expected.insert("Alice".to_string(), 25);
expected.insert("Bob".to_string(), 30);
expected.insert("Charlie".to_string(), 35);
assert_eq!(map, expected);

use lowdash::slice_to_map;
use std::collections::HashMap;

let strings = vec!["apple", "banana", "apricot", "blueberry"];
let map = slice_to_map(&strings, |s| (s.chars().next().unwrap(), s.len()));
let mut expected = HashMap::new();
expected.insert('a', 7); // "apricot" has 7 characters
expected.insert('b', 9); // "blueberry" has 9 characters
assert_eq!(map, expected);

drop

Removes the first n elements from a collection and returns the remaining elements.

use lowdash::drop;

let numbers = vec![1, 2, 3, 4, 5];
let result = drop(&numbers, 2);
assert_eq!(result, vec![3, 4, 5]);

use lowdash::drop;

let letters = vec!['a', 'b', 'c', 'd'];
let result = drop(&letters, 10);
assert_eq!(result, vec![]);

drop_right

Removes the last n elements from a collection and returns the remaining elements.

use lowdash::drop_right;

let numbers = vec![1, 2, 3, 4, 5];
let result = drop_right(&numbers, 2);
assert_eq!(result, vec![1, 2, 3]);

use lowdash::drop_right;

let letters = vec!['a', 'b', 'c', 'd'];
let result = drop_right(&letters, 10);
assert_eq!(result, vec![]);

drop_while

Removes elements from the beginning of a collection as long as a predicate returns true, and returns the remaining elements. As soon as the predicate returns false, the function stops dropping elements.

use lowdash::drop_while;

let numbers = vec![1, 2, 3, 4, 5];
let result = drop_while(&numbers, |&x| x < 3);
assert_eq!(result, vec![3, 4, 5]);

use lowdash::drop_while;

let letters = vec!['a', 'b', 'c', 'd'];
let result = drop_while(&letters, |&c| c < 'c');
assert_eq!(result, vec!['c', 'd']);

drop_right_while

Removes elements from the end of a collection as long as a predicate returns true, and returns the remaining elements. As soon as the predicate returns false, the function stops dropping elements.

use lowdash::drop_right_while;

let numbers = vec![1, 2, 3, 4, 5];
let result = drop_right_while(&numbers, |&x| x > 3);
assert_eq!(result, vec![1, 2, 3]);

use lowdash::drop_right_while;

let letters = vec!['a', 'b', 'c', 'd', 'e'];
let result = drop_right_while(&letters, |&c| c != 'c');
assert_eq!(result, vec!['a', 'b', 'c']);

drop_by_index

Removes elements from a collection at the specified indices. Supports negative indices which count from the end of the collection. Indices that are out of bounds are ignored.

use lowdash::drop_by_index;

let numbers = vec![1, 2, 3, 4, 5];
let result = drop_by_index(&numbers, &[1, 3]);
assert_eq!(result, vec![1, 3, 5]);

use lowdash::drop_by_index;

let letters = vec!['a', 'b', 'c', 'd', 'e'];
let result = drop_by_index(&letters, &[0, -1]);
assert_eq!(result, vec!['b', 'c', 'd']);

reject_map

Applies a callback function to each item in a collection along with its index and collects the results where the callback returns false.

use lowdash::reject_map;

let numbers = vec![1, 2, 3, 4, 5];
// Collect squares of odd numbers
let result = reject_map(&numbers, |&x, _| (x * x, x % 2 == 0));
assert_eq!(result, vec![1, 9, 25]);

use lowdash::reject_map;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

// Collect names of people who are not above 30
let result = reject_map(&people, |person, _| (person.name.clone(), person.age > 30));
assert_eq!(result, vec!["Alice".to_string(), "Bob".to_string()]);

filter_reject

Filters a collection into two separate vectors based on a predicate function.

use lowdash::filter_reject;

let numbers = vec![1, 2, 3, 4, 5];
// Separate even and odd numbers
let (evens, odds) = filter_reject(&numbers, |&x, _| x % 2 == 0);
assert_eq!(evens, vec![2, 4]);
assert_eq!(odds, vec![1, 3, 5]);

use lowdash::filter_reject;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];

// Separate people who are at least 30 years old
let (adults, juniors) = filter_reject(&people, |person, _| person.age >= 30);
assert_eq!(adults, vec![
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
]);
assert_eq!(juniors, vec![
    Person { name: "Alice".to_string(), age: 25 },
]);

count

Counts the number of occurrences of a specific value in a collection.

use lowdash::count;

let numbers = vec![1, 2, 2, 3, 4, 2];
let result = count(&numbers, 2);
assert_eq!(result, 3);

use lowdash::count;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
];

let count_alice = count(&people, Person { name: "Alice".to_string(), age: 25 });
assert_eq!(count_alice, 2);

count_by

Counts the number of elements in a collection that satisfy a given predicate.

use lowdash::count_by;

let numbers = vec![1, 2, 3, 4, 5];
// Count even numbers
let result = count_by(&numbers, |&x| x % 2 == 0);
assert_eq!(result, 2);

use lowdash::count_by;

#[derive(Debug, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
    Person { name: "Dave".to_string(), age: 30 },
];

// Count people who are at least 30 years old
let count_adults = count_by(&people, |p| p.age >= 30);
assert_eq!(count_adults, 3);

count_values

Counts the number of occurrences of each value in a collection.

use lowdash::count_values;
use std::collections::HashMap;

let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let result = count_values(&numbers);
let mut expected = HashMap::new();
expected.insert(1, 1);
expected.insert(2, 2);
expected.insert(3, 2);
expected.insert(4, 1);
expected.insert(5, 1);
assert_eq!(result, expected);

use lowdash::count_values;
use std::collections::HashMap;

#[derive(Debug, PartialEq, Eq, Hash, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let result = count_values(&people);
let mut expected = HashMap::new();
expected.insert(
    Person { name: "Alice".to_string(), age: 25 },
    2
);
expected.insert(
    Person { name: "Bob".to_string(), age: 30 },
    1
);
expected.insert(
    Person { name: "Carol".to_string(), age: 35 },
    1
);
assert_eq!(result, expected);

count_values_by

Counts the number of occurrences of each value in a collection after applying a mapper function.

use lowdash::count_values_by;
use std::collections::HashMap;

let chars = vec!['a', 'b', 'a', 'c', 'b', 'd'];
let result = count_values_by(&chars, |x| x.clone());
let mut expected = HashMap::new();
expected.insert('a', 2);
expected.insert('b', 2);
expected.insert('c', 1);
expected.insert('d', 1);
assert_eq!(result, expected);

use lowdash::count_values_by;
use std::collections::HashMap;

 let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let result = count_values_by(&numbers, |x| *x);
let mut expected = HashMap::new();
expected.insert(1, 1);
expected.insert(2, 2);
expected.insert(3, 2);
expected.insert(4, 1);
expected.insert(5, 1);
assert_eq!(result, expected);

subset

Returns a subset of the collection based on the provided offset and length.

use lowdash::subset;

let numbers = vec![1, 2, 3, 4, 5];
let result = subset(&numbers, 1, 3);
assert_eq!(result, vec![2, 3, 4]);

slice

Returns a subset of the collection based on the provided start and end indices.

use lowdash::slice;

let numbers = vec![1, 2, 3, 4, 5];
let result = slice(&numbers, 1, 3);
assert_eq!(result, vec![2, 3]);

use lowdash::slice;

let numbers = vec![1, 2, 3, 4, 5];
let result = slice(&numbers, -3, -1);
assert_eq!(result, vec![3, 4]);

use lowdash::slice;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
    Person { name: "Dave".to_string(), age: 40 },
];

let result = slice(&people, 1, 3);
assert_eq!(
    result,
    vec![
        Person { name: "Bob".to_string(), age: 30 },
        Person { name: "Carol".to_string(), age: 35 },
    ]
);

replace

Replaces occurrences of a specified value in a collection with a new value, up to a maximum number of replacements.

use lowdash::replace;

let numbers = vec![1, 2, 2, 3, 4, 2, 5];
let result = replace(&numbers, 2, 9, 2);
assert_eq!(result, vec![1, 9, 9, 3, 4, 2, 5]);

use lowdash::replace;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let new_person = Person { name: "Dave".to_string(), age: 40 };
let result = replace(&people, people[0].clone(), new_person.clone(), 1);
assert_eq!(result, vec![new_person, people[1].clone(), people[2].clone(), people[3].clone()]);

replace_all

Replaces all occurrences of a specified value in a collection with a new value.

use lowdash::replace_all;

let numbers = vec![1, 2, 2, 3, 4, 2, 5];
let result = replace_all(&numbers, 2, 9);
assert_eq!(result, vec![1, 9, 9, 3, 4, 9, 5]);

use lowdash::replace_all;

#[derive(Debug, PartialEq, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let dave = Person { name: "Dave".to_string(), age: 40 };
let result = replace_all(&people, people[0].clone(), dave.clone());
assert_eq!(
    result,
    vec![
        dave.clone(),
        people[1].clone(),
        dave.clone(),
        people[3].clone(),
    ]
);

compact

Removes all zero-valued elements from a collection, preserving the order of non-zero elements.

This function iterates over a slice of items, removing each element that is equal to the zero value. The zero value is determined by the Default trait implementation for the type T. The function preserves the order of the remaining elements and does not modify the original collection.

Time Complexity: O(n), where n is the number of elements in the collection.

Arguments

• collection - A slice of items from which to remove zero-valued elements.

Type Parameters

• T - The type of elements in the collection. Must implement PartialEq, Clone, and Default.

Returns

• Vec<T> - A new vector containing only the non-zero elements from the input collection.

Examples

use lowdash::compact;

let numbers = vec![0, 1, 0, 2, 3, 0, 4];
let compacted = compact(&numbers);
assert_eq!(compacted, vec![1, 2, 3, 4]);

use lowdash::compact;

#[derive(Debug, PartialEq, Clone, Default)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "".to_string(), age: 0 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "".to_string(), age: 0 },
    Person { name: "Dave".to_string(), age: 40 },
];

let compacted = compact(&people);
assert_eq!(
    compacted,
    vec![
        Person { name: "Bob".to_string(), age: 30 },
        Person { name: "Dave".to_string(), age: 40 },
    ]
);

use lowdash::compact;

let floats = vec![0.0, 1.1, 0.0, 2.2, 3.3, 0.0, 4.4];
let compacted = compact(&floats);
assert_eq!(compacted, vec![1.1, 2.2, 3.3, 4.4]);

is_sorted

Determines if a collection is sorted in ascending order.

use lowdash::is_sorted;

let numbers = vec![1, 2, 3, 4, 5];
assert_eq!(is_sorted(&numbers), true);

use lowdash::is_sorted;

let numbers = vec![5, 4, 3, 2, 1];
assert_eq!(is_sorted(&numbers), false);

use lowdash::is_sorted;

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];
assert_eq!(is_sorted(&people), true);

use lowdash::is_sorted;

let floats = vec![1.1, 2.2, 3.3, 4.4];
assert_eq!(is_sorted(&floats), true);

use lowdash::is_sorted;

let floats = vec![1.1, std::f64::NAN, 3.3];
// Note: Any comparison with NaN returns false, so the slice is not considered sorted.
assert_eq!(is_sorted(&floats), false);

is_sorted_by_key

Determines if a collection is sorted in ascending order based on a specified key.

use lowdash::is_sorted_by_key;

let numbers = vec![
    (1, "a"),
    (2, "b"),
    (3, "c"),
    (4, "d"),
];
let result = is_sorted_by_key(&numbers, |item| item.0);
assert_eq!(result, true);

use lowdash::is_sorted_by_key;

let numbers = vec![
    (1, "a"),
    (3, "b"),
    (2, "c"),
    (4, "d"),
];
let result = is_sorted_by_key(&numbers, |item| item.0);
assert_eq!(result, false);

use lowdash::is_sorted_by_key;

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Carol".to_string(), age: 35 },
];
let result = is_sorted_by_key(&people, |p| p.age);
assert_eq!(result, true);

use lowdash::is_sorted_by_key;

let floats = vec![
    (1.1, "apple"),
    (2.2, "banana"),
    (3.3, "cherry"),
    (4.4, "date"),
];
let result = is_sorted_by_key(&floats, |item| item.0);
assert_eq!(result, true);

splice

Inserts elements into a collection at a specified index, handling negative indices and overflow.

use lowdash::splice;

let numbers = vec![1, 2, 3, 4, 5];
let elements = vec![99, 100];
let result = splice(&numbers, 2, &elements);
assert_eq!(result, vec![1, 2, 99, 100, 3, 4, 5]);

use lowdash::splice;

let numbers = vec![1, 2, 3, 4, 5];
let elements = vec![99, 100];
// Insert at the end
let result = splice(&numbers, 10, &elements);
assert_eq!(result, vec![1, 2, 3, 4, 5, 99, 100]);

use lowdash::splice;

let numbers = vec![1, 2, 3, 4, 5];
let elements = vec![99];
// Insert at negative index (-2 means len - 2 = 3)
let result = splice(&numbers, -2, &elements);
assert_eq!(result, vec![1, 2, 3, 99, 4, 5]);

use lowdash::splice;

let numbers = vec![1, 2, 3, 4, 5];
let elements = vec![99];
// Negative index beyond the start, insert at beginning
let result = splice(&numbers, -10, &elements);
assert_eq!(result, vec![99, 1, 2, 3, 4, 5]);

🫡 Acknowledgement

This project is inspired by lodash and lo