The first one is ScalaQuery. It is the most mature one, and it tries to make queries use the same for-comprehension as Scala collections do.
The second one is Querulous, which is a open source project from Twitter. This one gives you direct access to SQL, while dealing with a bunch of jdbc annoyances.
The third one is Squeryl. Style-wise, it sits midway between ScalaQuery — which hides SQL behind Scala comprehensions as much as possible — and Querulous — which uses SQL strings directly.
Squeryl provides a SQL-like DSL, which gives you type safety and give you a strong likelyhood that the statements won’t fail at run-time if they compile at all
- O/R Broker
The fourth is O/R Broker, which, despite the name, is not an ORM. Classes can be designed in any way desired. No interfaces/traits to implement, no conventions to uphold, no annotations needed