Introduction

Sapio is a Rust framework for describing Bitcoin contracts as transaction graphs. It separates constructing transactions, defining their spending policies and supplying the signatures or program evidence needed to complete a selected spend.

The first lesson uses the maintained generated starter and its tested contract source. Later chapters include historical examples and conceptual sketches; use the current repository guides when an older sketch differs from the public API. Rendering this book does not compile every code block.

Who is Sapio For?

Sapio is for anyone who wants to build with Bitcoin. That spans students demonstrating research concepts, corporations working on custody solutions, and developers improving open source solutions. Sapio is not a Solidity equivalent. The programming model is very different. But it does help anyone trying to solve a transactional protocol for Bitcoin solve it elegantly.

The developer preview uses synthetic funding and public demonstration keys. Native covenant research and oracle-based emulation have distinct enforcement assumptions. Completing the lesson does not establish production readiness; the release-readiness record lists the remaining gates.

What will I learn if I read this book?

This book is intended to teach you how to think about programming Sapio contracts. The book contains some exercises (that are heavily encouraged) that should instigate your understanding of how to build smart contracts for Bitcoin.

If you go through the chapters in order and complete all the exercises you should develop a firm grasp of how to use Sapio, how it works, and how it will progress over time. You will also have sufficient understanding to contribute back meaningfully to the open source project.