Tutorial

The Get started page drops a working loop in your lap at once. This tutorial is the slow version: you build the same kind of application by hand, and at each step we separate the idea (a CQRS/event-sourcing principle that's true in any language) from the mechanism (how FCQRS happens to implement it). Where the machinery is overkill for a given app, we'll say so — the point is judgment, not selling a framework.

What you'll build is a small document store, the same domain as the worked example focument_fsharp: you create and edit versioned documents, a read model tracks them, and — by the end — a quota saga gates new documents across a second aggregate.

What you need

The .NET 10 SDK (dotnet --version should print 10.*).
A scratch project. Create one now; every chapter adds to its Program.fs:

dotnet new console -lang F# -n DocStore
cd DocStore
dotnet add package FCQRS --prerelease   # the F# facade ships in the 6.0 previews

Run it at any point with dotnet run. The first run creates a SQLite file next to the binary (the journal — your event log); delete *.db* if you ever want a clean slate.

Each chapter's code uses the idiomatic-F# facade FCQRS.FSharp, and chapters 1–2 are compiled against the pinned package as part of building this site, so what you read here is what the compiler accepts.

The three chapters

*The aggregate* — the write side. What a command and an event really are, why they're different sets, and the two pure functions (decide, fold) that are the whole of your domain logic. No actors yet — just types you can unit-test.
*Wiring and running it* — turn those functions into a running, persistent actor with no HOCON, add a read model, send a command, and watch the version climb across restarts — your first real taste of event sourcing.
*Adding a saga* — a rule that spans two entities (a per-user quota) that an aggregate structurally cannot enforce alone, and the process manager that can.

Each chapter links into Concepts when you want the long-form reasoning behind a piece.