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Fe is an emerging smart contract language for the Ethereum blockchain.

Build Status Coverage

NOTE: The larger part of the master branch will be replaced with the brand-new implementation, which is currently under development in the fe-v2 branch. Please refer to the branch if you kindly contribute to Fe

Overview

Fe is a statically typed language for the Ethereum Virtual Machine (EVM). It is inspired by Rust and easy to learn -- especially for new developers entering the Ethereum ecosystem.

Features & Goals

Additional information about design goals and background can be found in the official announcement.

Language Specification

We aim to provide a full language specification that should eventually be used to formally verify the correctness of the compiler. A work in progress draft of the specification can be found here.

Progress

Fe development is still in its early stages. We have a basic Roadmap for 2021 that we want to follow. We generally try to drive the development by working through real world use cases. Our next goal is to provide a working Uniswap implementation in Fe which will help us to advance and form the language.

Fe had its first alpha release January 2021 and is now following a monthly release cycle.

Getting started

To compile Fe code:

  1. Run fe path/to/fe_source.fe
  2. Fe creates a directory output in the current working directory that contains the compiled binary and abi.

Run fe --help to explore further options.

Examples

The following is a simple contract implemented in Fe.

struct Signed {
    pub book_msg: String<100>
}

contract GuestBook {
    messages: Map<address, String<100>>

    pub fn sign(mut self, mut ctx: Context, book_msg: String<100>) {
        self.messages[ctx.msg_sender()] = book_msg
        ctx.emit(Signed(book_msg: book_msg))
    }

    pub fn get_msg(self, addr: address) -> String<100> {
        return self.messages[addr].to_mem()
    }
}

A lot more working examples can be found in our test fixtures directory.

The most advanced example that we can provide at this point is an implementation of the Uniswap-V2 core contracts.

Community

License

The Fe implementation is split into several crates. Crates that depend on the solidity compiler (directly or indirectly) are licensed GPL-3.0-or-later. This includes the fe CLI tool, yulc, driver, tests, and test-utils.

The remaining crates are licensed Apache-2.0. This includes the parser, analyzer, mir, abi, and common.