Map, Reduce, Filter Library

A useful library for working with arrays. I mostly use them for convenience when writing tests and keeping code readable. This library provides three functions for manipulating arrays in Solidity: map(), reduce(), and filter().

import {Map, Reduce, Filter} from "soltheon/src/MapReduceFilter.sol";

contract Example {
    using Map for uint256[];
    using Reduce for uint256[];
    using Filter for uint256[];
    using Filter for address[];
}

Map

The map() function applies a given callback function to each element of an array and returns a new array with the results.

function square(uint256 x) pure returns (uint256) {
    return x * x;
}

uint256[] memory arr = [1, 2, 3, 4, 5];
uint256[] memory squared = arr.map(square);
// squared is now [1, 4, 9, 16, 25]

supported types: uint256[]

Reduce

The reduce() function applies a given callback function to each element of an array, accumulating a single result.

function sum(uint256 a, uint256 b) pure returns (uint256) {
    return a + b;
}

uint256[] memory arr = [1, 2, 3, 4, 5];
uint256 total = arr.reduce(sum);
// total is now 15

supported types: uint256[]

Filter

The filter() function applies a given callback function to each element of an array and returns a new array containing only the elements for which the callback returns true.

function isEven(uint256 x) pure returns (bool) {
    return x % 2 == 0;
}

uint256[] memory arr = [1, 2, 3, 4, 5];
uint256[] memory even = arr.filter(isEven);
// even is now [2, 4]

The filter() function also works with arrays of address types.

function isContract(address a) view returns (bool) {
    return a.code.length > 0;
}


address[] memory addresses = [address(this), address(0x123), address(0x456)];
address[] memory contractAddresses = addresses.filter(isContract);
// only the contracts remain in the list

supported types: uint256[], address[]

Test

$ forge test

Security

The code is tested but not audited. Use it at your own risk.

Contributing

Contributions to the library are welcome. Please submit pull requests if you want to add more uint sizes or any other desired types.

License

This project is licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later).

For more details visit GNU General Public License v3.0 or later.