https://github.com/disco-dave/message-db
Haskell client library for Eventide's Message DB
https://github.com/disco-dave/message-db
cqrs database event-sourcing haskell postgresql
Last synced: 4 months ago
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Haskell client library for Eventide's Message DB
- Host: GitHub
- URL: https://github.com/disco-dave/message-db
- Owner: Disco-Dave
- License: mit
- Created: 2022-04-08T22:38:54.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2022-12-05T02:06:17.000Z (about 3 years ago)
- Last Synced: 2025-10-21T13:56:55.532Z (4 months ago)
- Topics: cqrs, database, event-sourcing, haskell, postgresql
- Language: Haskell
- Homepage:
- Size: 342 KB
- Stars: 6
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: ChangeLog.md
- License: LICENSE
Awesome Lists containing this project
README
# message-db - Client library for Eventide's Message DB
Collection of libraries for interacting with [Eventide's Message DB](http://docs.eventide-project.org/user-guide/message-db/) via PostgreSQL.
The purpose of these libraries are to make it easier to implement event sourcing
systems in Haskell.
For an example of how this library is used, please see [BankAccount.hs](./message-db/test/Examples/BankAccount.hs).
### Disclaimers
- This library is an unofficial message-db client library for Haskell.
- Only `message-db-temp` has been published to [hackage](https://hackage.haskell.org/package/message-db-temp) so far.
- If you want to use the `message-db` or `message-db-monad` packages then you need to add the following:
- For `cabal` add the following to `cabal.project`
```cabal
source-repository-package
type: git
location: https://github.com/Disco-Dave/message-db.git
tag: 359cb51b69efbf8f561c2709973db713c8154a34
subdir:
message-db
message-db-monad
```
- For `stack` add the follow to `stack.yaml`
```yaml
extra-deps:
- git: https://github.com/Disco-Dave/message-db.git
commit: 359cb51b69efbf8f561c2709973db713c8154a34
subdirs:
- message-db
- message-db-monad
```
- Note: you may replace `359cb51b69efbf8f561c2709973db713c8154a34` with any git ref you want
## Repository Structure
This repository contains the following packages:
- [message-db](./message-db) - Low-level library built on top of [postgresql-simple](https://hackage.haskell.org/package/postgresql-simple).
- [message-db-temp](./message-db-temp) - Creates temporary message-db instances using [tmp-postgres](https://hackage.haskell.org/package/tmp-postgres) and the [official message-db scripts](https://github.com/message-db/message-db). This package is also used by [message-db tests](./message-db/test/) for running integration tests.
- [message-db-monad](./message-db-monad) - Utilizes [MonadUnliftIO](https://hackage.haskell.org/package/unliftio-core-0.2.0.1/docs/Control-Monad-IO-Unlift.html#t:MonadUnliftIO) to allow running message-db actions in a custom monad.
## How to Get Help
If you find a bug, have a feature request, or simply have a question then please [open an issue](https://github.com/Disco-Dave/message-db/issues/new).
## How to Build
Currently this project supports that last three major versions of `ghc` with `cabal`, and the last two major `lts` snapshots plus `nightly` for `stack`.
If you need to setup `ghc`, `cabal`, or `stack`; then I highly recommend using [ghcup](https://www.haskell.org/ghcup/).
### Preparation
Regardless of which tool chain you use, the first thing you'll need to do is clone the repo and initialize all of the submodules. This may be done with one command:
`git clone https://github.com/Disco-Dave/message-db.git --recurse-submodules`
Or if you already cloned the repo, then you may run the following inside of the repo folder to initialize the submodules:
`git submodule update --init --recursive`
You may also need some additional system dependencies in order to build, if you're on a Debian based system then run the following:
`apt update && apt install -y libpq-dev`
If you also wish to run the test-suite, then you need to make sure that `initdb` is on your path. If you're on a Debian based system then run the following:
```bash
apt update && apt install -y postgresql
export PATH=/usr/lib/postgresql/13/bin:$PATH
```
Note, your distro may have a `postgresql` version different from 13. If so, replace the 13 in your `PATH` with the appropriate number.
### Cabal Instructions
1. `cabal update` - Ensures you have the latest package list from [Hackage](https://hackage.haskell.org/).
2. `cabal build all` - Builds _all_ packages.
3. `cabal test all` - Runs the test-suite for _all_ packages.
### Stack Instructions
1. `stack init` - Initializes the stack project. You can also specify a specific `resolver` instead:
- `stack init --resolver lts-18`
- `stack init --resolver lts-19`
- `stack init --resolver nightly`
2. `stack build` - Builds _all_ packages.
3. `stack test` - Runs the test-suite for _all_ packages.
## Learn More about Eventide's Message DB
- [Docs - Official Message DB user guide](http://docs.eventide-project.org/user-guide/message-db)
- [Reference - Official postgres client in Ruby](https://github.com/eventide-project/message-store-postgres)
- [Blog - Build Your Own Message DB Client](https://blog.eventide-project.org/articles/build-your-own-message-db-client/)
- [Book - Practical Microservices](https://pragprog.com/titles/egmicro/practical-microservices/)