https://github.com/valderman/selda

A type-safe, high-level SQL library for Haskell
https://github.com/valderman/selda

dsl haskell-library postgresql sql sqlite

Last synced: about 2 months ago
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A type-safe, high-level SQL library for Haskell

• Host: GitHub
• URL: https://github.com/valderman/selda
• Owner: valderman
• License: mit
• Created: 2017-04-08T21:15:10.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2024-03-19T05:54:49.000Z (6 months ago)
• Last Synced: 2024-04-25T20:46:22.222Z (5 months ago)
• Topics: dsl, haskell-library, postgresql, sql, sqlite
• Language: Haskell
• Homepage: https://selda.link
• Size: 1.04 MB
• Stars: 476
• Watchers: 17
• Forks: 53
• Open Issues: 46
• Metadata Files:
  • Readme: README.md
  • Changelog: ChangeLog.hs
  • License: LICENSE

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• my-awesome - valderman/selda - library,postgresql,sql,sqlite pushed_at:2024-06 star:0.5k fork:0.1k A type-safe, high-level SQL library for Haskell (Haskell)

README

        
Selda

=====

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What is Selda?

==============

[Selda](https://selda.link) is a Haskell library for interacting with SQL-based relational databases.

It was inspired by [LINQ](https://en.wikipedia.org/wiki/Language_Integrated_Query) and

[Opaleye](http://hackage.haskell.org/package/opaleye).

Features

========

* Monadic interface.

* Portable: backends for SQLite and PostgreSQL.

* Generic: easy integration with your existing Haskell types.

* Creating, dropping and querying tables using type-safe database schemas.

* Typed query language with products, filtering, joins and aggregation.

* Inserting, updating and deleting rows from tables.

* Conditional insert/update.

* Transactions, uniqueness constraints and foreign keys.

* Type-safe, backend-specific functionality, such as JSON lookups.

* Seamless prepared statements.

* Lightweight and modular: few dependencies, and non-essential features are

  optional or split into add-on packages.

Getting started

===============

Install the `selda` package from Hackage, as well as at least one of the

backends:

    $ cabal update

    $ cabal install selda selda-sqlite selda-postgresql

Then, read [the tutorial](https://selda.link/tutorial).

The [API documentation](http://hackage.haskell.org/package/selda) will probably

also come in handy.

Requirements

============

Selda requires GHC 8.0+, as well as SQLite 3.7.11+ or PostgreSQL 9.4+.

To build the SQLite backend, you need a C compiler installed.

To build the PostgreSQL backend, you need the `libpq` development libraries

installed (`libpq-dev` on Debian-based Linux distributions).

Hacking

=======

Contributing

------------

All forms of contributions are welcome!

If you have a bug to report, please try to include as much information as

possible, preferably including:

* A brief description (one or two sentences) of the bug.

* The version of Selda+backend where the bug was found.

* A step-by-step guide to reproduce the bug.

* The *expected* result from following these steps.

* What *actually* happens when following the steps.

* Which component contains the bug (selda, selda-sqlite or selda-postgresql),

  if you're reasonably sure about where the bug is.

Bonus points for a small code example that illustrates the problem.

If you want to contribute code, please consult the following checklist before

sending a pull request:

* Does the code build with a recent version of GHC?

* Do all the tests pass?

* Have you added any tests covering your code?

If you want to contribute code but don't really know where to begin,

issues tagged [good first issue](https://github.com/valderman/selda/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) are a good start.

Setting up the build environment

--------------------------------

From the repository root:

* Install `libpq-dev` from your package manager.

    This is required to build the PostgreSQL backend.

* Make sure you're running a cabal version that supports v2-style commands.

* Familiarise yourself with the various targets in the makefile.

    The dependencies between Selda, the backends and the tests are slightly

    complex, so straight-up cabal is too quirky for day to day hacking.

PostgreSQL backend testing with Docker

--------------------------------------

To test the PostgreSQL backend, use the provided `pgtest-compose.yml` docker-compose file:

```

sudo docker-compose -f pgtest-compose.yml up -d

make pgtest

sudo docker-compose -f pgtest-compose.yml down

```

TODOs

-----

Features that would be nice to have but are not yet implemented.

* Monadic if/else

* Streaming

* MySQL/MariaDB backend

* MSSQL backend