signed_integers

Overview

The Signed Integers library provides a library to use signed numbers in Sway. It has 6 distinct types: I8, I16, I32, I64, I128, I256. These types are stack allocated.

These types are stored as unsigned integers, therefore either u64 or a number of them. Therefore the size can be known at compile time and the length is static.

For more information please see the specification.

Using the Library

Getting Started

In order to use the Signed Integers type it must be added to the Forc.toml file.

signed_integers = { git = "https://github.com/fuellabs/sway-libs", branch = "master" }

Then we can import types like so:

use signed_integers::i8::I8;

Once imported, a Signed Integer type can be instantiated defining a new variable and calling the new function.

let mut i8_value = I8::new();

Basic Functionality

Basic arithmetic operations are working as usual

// Add 2 signed values
let i8_value_3 = i8_value_1 + i8_value_2;

// Subtract one signed value from another
let i8_value_3 = i8_value_1 - i8_value_2;

Helper functions

// To get a negative value from an unsigned value 
let neg_value = I8::neg_from();

// Maximum value
let max_i8_value = I8::max();

Known Issues

The current implementation of U128 and U256 will compile large bytecode sizes when performing mathematical computations. As a result, I128 and I256 inherit the same issue and could cause high transaction costs. This should be resolved with future optimizations of the Sway compiler.