Eventium Examples

Example applications for Eventium, the Haskell event sourcing library:

• bank — account aggregates, command handlers, a process manager, and a Transfer read model (persistent, SQLite-backed).
• cafe — a café tab aggregate with an interactive terminal UI.
• counter-cli — a minimal counter aggregate over the in-memory store.

Development

Prerequisites: Nix (with flakes) + direnv. Entering the directory auto-loads the dev shell via .envrc; the shell runs hpack to generate the .cabal files.

This repo builds against a sibling checkout of the library, matching the eventium-hs layout:

eventium-hs/
├── eventium/    # the library
└── examples/    # this repo

just build-local   # build against ../eventium (local dev)
just test          # run example tests against ../eventium
just format        # ormolu --mode inplace
just lint          # hlint

Project files

• cabal.project.dev — local development against ../eventium (used by just build-local / just test). Works today.
• cabal.project — self-contained build that pulls the library from git (source-repository-package). This becomes usable once the eventium-hs/eventium repo exists and commits its generated .cabal files (cabal does not run hpack on git dependencies).