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When the topic of JDBC wrappers came up on the Scala mailing list a few weeks ago, I mentioned that…

I’d prefer a type-safe DSL for database queries but that’s more
complicated. I’m still experimenting with that, too

I think those experiments worked rather well and the code is now in a state where the major features are usable and I can show some example code which compiles and runs successfully as a proof of concept. Many features (like more SQL operators, more data types and column aliasing) are missing but at least I am confident that it is possible to implement them on this basis.

Just like HaskellDB and LINQ to SQL, I am using a query monad which collects the projections and restrictions on database tables in a composable way to build an SQL statement for a query while producing the correct type for that statement’s result in Scala’s type system. Don’t worry if that sounds too abstract, there will be plenty of example code. (more…)