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

NOTE: Most of the master branch will be replaced with a 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). The type system is similar to rust's, with the addition of higher-kinded types (on the fe-v2 branch). We're exploring additional type system, syntax, and semantic changes. Please note that the current docs reflect the status of the language on the master branch.

Progress

Fe has had several early releases which can be used today, though these releases are lacking some features and don't reflect our complete vision for the language. The current focus is on finishing the fe-v2 branch, and development of the sonatina compiler backend which Fe will use.

Getting started

• Build the compiler
• Or download the binary release

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()
    }
}

More 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

• Twitter: @official_fe
• Chat:
  • We've recently moved to Zulip
  • The Discord server is still live, but our preference is zulip.

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.