Type-safe, composable SQL for ZIO applications


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Current status: Non-production release

Progress report towards 0.1

✔️ - good to go

- some more work needed

General features:

Feature Progress
Type-safe schema ✔️
Type-safe DSL ✔️
Running Reads ✔️
Running Deletes ✔️
Running Updates ✔️
Running Inserts ✔️
Connection pool

Db-specific features:

Feature PostgreSQL SQL Server Oracle MySQL
Render Read ✔️ ✔️ ✔️ ✔️
Render Delete ✔️ ✔️ ✔️ ✔️
Render Update ✔️ ✔️ ✔️
Render Insert ✔️ ✔️ ✔️
Functions ✔️ ✔️ ✔️ ✔️

What is ZIO SQL?

ZIO SQL lets you write type-safe, type-inferred, and composable SQL queries in ordinary Scala, helping you prevent persistence bugs before they happen, and leverage your IDE to make writing SQL productive, safe, and fun.

  • Type-safety. ZIO SQL queries are type-safe by construction. Most classes of bugs can be detected at compile-time, shortening your feedback loop and helping you use your IDE to write correct queries.
  • Composable. All ZIO SQL components are ordinary values, which can be transformed and composed in sensible ways. This uniformity and regularity means you have a lot of power in a small package.
  • Type-inferred. ZIO SQL uses maximal variance and lower-kinded types, which means it features very good type inference. You can let Scala figure out the types required for type-safe SQL.
  • No magic. ZIO SQL does not need any macros or plug-ins to operate (everything is a value!), and it works across both Scala 2.x and Scala 3. Optionally, Scala schema can be created from database schemas.

ZIO SQL can be used as a library for modeling SQL in a type-safe ADT. In addition, ZIO SQL has a JDBC interface, which utilizes the type-safe SQL ADT for interacting with common JDBC databases.

For the JDBC module:

  • Like Slick, ZIO SQL has an emphasis on type-safe SQL construction using Scala values and methods. However, ZIO SQL utilizes reified lenses, contravariant intersection types, and in-query nullability to improve ergonomics for end-users. Unlike Slick, the intention is to use names resembling SQL instead of trying to mimic the Scala collections.
  • Like Doobie, ZIO SQL is purely functional, but ZIO SQL does compile-time query validation that catches most issues, and has rich ZIO integration, offering improved type-safety compared to monofunctor effects and minimal dependencies (depending only on ZIO).

ZIO SQL does not offer Language Integrated Queries (LINQ) or similar functionality. It is intended only as a data model for representing SQL queries and an accompanying lightweight JDBC-based executor.


Prerequisites (installed):

Technology Version
sbt 1.4.3
Docker 3.1

To set up the project follow below steps:

  1. Fork the repository.
  2. Setup the upstream (Extended instructions can be followed here).
  3. Make sure you have installed sbt and Docker.
  4. In project directory execute sbt test.
  5. Pick up an issue & you are ready to go!

If you want to learn more, please check out: