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Nodash - Lodash for Noir

Nodash is a utility library for Noir language.

Installation

Put this into your Nargo.toml.

If you are using Noir:

nodash = { git = "https://github.com/olehmisar/nodash/", tag = "v0.38.0" }

The version of nodash matches the version of Noir. The patch version may be different if a bugfix or a new feature is added for the same version of Noir. E.g., nodash@v0.38.0 and nodash@v0.38.1 are compatible with noir@v0.38.0.

Docs

sqrt

use nodash::sqrt;

assert(sqrt(4 as u64) == 2);

// it floors the result
assert(sqrt(8 as u64) == 2);

clamp

use nodash::clamp;

// if too small, return min
assert(clamp(1 as u64, 2 as u64, 3 as u64) == 2 as u64);
// if too big, return max
assert(clamp(4 as u64, 1 as u64, 3 as u64) == 3 as u64);
// if in range, return value
assert(clamp(2 as u64, 1 as u64, 3 as u64) == 2 as u64);

div_ceil

Calculates a / b rounded up to the nearest integer.

use nodash::div_ceil;

assert(div_ceil(10 as u64, 3) == 4);

solidity::encode_with_selector

Equivalent to abi.encodeWithSelector in Solidity.

use nodash::solidity::encode_with_selector;

let selector: u32 = 0xa9059cbb; // transfer(address,uint256)
let args: [Field; 2] = [
  0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045, // address
  123 // uint256
];
let encoded = encode_with_selector(selector, args);
// typeof encoded: [u8; 68]

to_hex_string_bytes

Converts a Field to a hex string.

let my_hash = 0x0d67824fead966192029093a3aa5c719f2b80262c4f14a5c97c5d70e4b27f2bf;
let expected = "0d67824fead966192029093a3aa5c719f2b80262c4f14a5c97c5d70e4b27f2bf";
assert_eq(to_hex_string_bytes(my_hash), expected.as_bytes());

str_to_u64

Converts a string to a u64.

use nodash::str_to_u64;

assert(str_to_u64("02345678912345678912") == 02345678912345678912);

ArrayExtensions

slice<L>(start: u32) -> [T; L]

Returns a slice of the array, starting at start and ending at start + L. Panics if start + L is out of bounds.

use nodash::ArrayExtensions;

assert([1, 2, 3, 4, 5].slice::<3>(1) == [2, 3, 4]);

concat

Concatenates two arrays.

use nodash::ArrayExtensions;

assert([1, 2, 3].concat([4, 5]) == [1, 2, 3, 4, 5]);

pad_start

Pads the start of the array with a value.

use nodash::ArrayExtensions;

assert([1, 2, 3].pad_start::<5>(0) == [0, 0, 1, 2, 3]);

pad_end

Pads the end of the array with a value.

use nodash::ArrayExtensions;

assert([1, 2, 3].pad_end::<5>(0) == [1, 2, 3, 0, 0]);

pack_bytes

Packs [u8; N] into [Field; N / 31 + 1]. Useful, if you need to get a hash over bytes. I.e., pedersen_hash(pack_bytes(bytes)) will be MUCH cheaper than pedersen_hash(bytes).

use nodash::pack_bytes;

let bytes: [u8; 32] = [0; 32];
let packed = pack_bytes(bytes);