RFC: hardhat-fe (Hardhat plugin to develop smart contracts with Fe)


hardhat-fe will be a Hardhat plugin to develop Ethereum based smart contracts with the new smart contract language Fe.

Possible usages:

  • hardhat compile to compile Fe based smart contract projects, will emit ABI files with the official Fe compiler releases.
  • hardhat test will run integration and unit tests for Fe based smart contract projects.
  • hardhat coverage will run test and generate coverage report for Fe based smart contract projects.


Fe is the next generation smart contract language for EVM based blockchains, and it introduces bunch of modern features which solidity does not arm with:

  • Bounds and overflow checking
  • Decidability by limitation of dynamic program behavior
  • More precise gas estimation (as a consequence of decidability)
  • Static typing
  • Pure function support
  • Restrictions on reentrancy
  • Static looping
  • Usage of YUL IR to target both EVM and eWASM
  • WASM compiler binaries for enhanced portability and in-browser compilation of Fe contracts
  • Implementation in a powerful, systems-oriented language (Rust) with strong safety guarantees to reduce risk of compiler bugs

I think the most interesting features are the static typing, program behavior decidability and eWASM support. the type system for Fe is almost derived from Rust without the ownership system, but it is still weaponed with a compiler-phase type checking with fully functional type inference engine.


we can start with this project with hardhat-vyper as a scaffold, and there is some key points we need to put attentions to:

  • the main part of the plugin is to download Fe compiler depending on running system, first we need to download release schema file, then we parse the schema file to get the browser_download_url as the download url to fetch the compiler binary, currently, Fe only support OSX and Linux 64bit.
  • the official examples provided by the Fe team are all written in a single .fe file, but our plugin need to be able to compile and test a whole project assembled with multiple .fe files, e.g. multiple module example.
  • this plugin should also be able to compile a project contains multiple smart contract languages mixed with Solidity and Fe or even with Vyper.

Please leave any feedback that you may have - good or bad. Excited to work on this project with y’all.

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Since the new user can only add two links for a single post, here is some extra links:

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thanks for this initiative! i know the Fe team is interested in help with plugin development.

  • have you interacted with the Fe team at all yet on their server?
  • if you’ve discussed this proposal anywhere in Discord, has anyone expressed interest in working on this with you?
  • are you looking for more support and is there any skill sets you think you could use help with?
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Hi @wolovim , the first version is already released GitHub - Developer-DAO/hardhat-fe: Hardhat plugin to develop smart contracts with Fe, the new project discussion in discord is here Discord, and thx for ur reply :slight_smile:

  1. marc has helped me for introducing this project to Fe team, and they are very interested on it.
  2. I posted this RFC in Discord, but seems on one was interested in this tooling oriented project, maybe there is no prototype yet, but right there is a handy project everyone can work with.
  3. the skill sets is only TypeScript and NodeJS, I can finish this project by my own, but if someone else also interest in this project can help me accelerate the progress which is really sweet.