Bitcoin Developers,

I'm very excited to introduce Sapio[0] formally to you all.

Sapio empowers Bitcoin Developers to craft smart contracts in an intuitive, safe, and composable way. Sapio challenges the notion that you can't make complex smart contracts for Bitcoin, and opens the floodgates for a myriad of new ideas to be defined easily. Sapio works today on mainnet without any protocol changes (via user-configurable multisig oracles, it will work with BIP-119 OP_CHECKTEMPLATEVERIFY[1] and Taproot when they are available).

You can learn more about what's possible by reading Designing Bitcoin Smart Contracts with Sapio[2]. My Reckless VR Talk[3] also does a great job of breaking down the core programming model for Sapio contracts, although the language has evolved substantially since I gave the talk.

As a concrete instance of Sapio working in the wild, I am currently executing on mainnet a Congestion Control Tree[4] contract with 25 recipients (the first Sapio contract to run on mainnet ever, as far as I'm aware). You can review the source code, arguments, compiler outputs, and transactions here[5].

To see more examples of what you can do with Sapio, the repo includes examples[6] for derivatives, vaults, coin pools, games, side chains, and more. These aren't intended to be production grade contracts -- yet -- but are demonstrative of what can be built and how. I'm excited to see what people build -- please open up PRs with your ideas or any issues you encounter trying to implement them.

You can also try out Tux[7], an experimental GUI, to inspect, simulate, and interact with smart contracts. You can see the Congestion Control Tree mentioned earlier loaded in Tux below[8]:

This is still early work-in-progress software, so tread lightly and use regtest. Enough of the components work today that it was appropriate to share now and invite more developers to contribute or otherwise support the project.

Sapio is developed free and open source for all bitcoiners by Judica.org (my organization).

Thank you to all who have helped reach this milestone of the first mainnet Sapio contract, including Ryan Grant, BitMEX, ACINQ, Delphi Digital, Backend Capital, my github sponsors https://github.com/sponsors/jeremyrubin, and numerous other supporters both fiscal and technical. I also want to highlight the excellent work done on Miniscript and the rust-bitcoin ecosystem, the foundation upon which Sapio rests.

[0] https://github.com/sapio-lang/sapio

[1] https://utxos.org

[2] https://learn.sapio-lang.org

[3] https://judica.org/blog/sapio/

[4] https://utxos.org/analysis/bip_simulation/

[5] https://gist.github.com/JeremyRubin/1374f0916bfdef0bd36bc10d73852886

[6] https://github.com/sapio-lang/sapio/tree/master/sapio-contrib/src/contracts

[7] https://github.com/sapio-lang/tux

[8] https://imgur.com/pg5SqfH

Eager for you feedback,

Jeremy

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@JeremyRubin