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I have been working on a typed relational algebra that allows to abstract and compose queries that can be verified statically. This means that the type system ensures all queries are well-formed and you never try to use a non-existent column or table or an existent one with the wrong types. There's no way a change to the DB schema can break your code silently. Query composition is sorely missing in most ORMs; you normally do some query and get in return a number of objects in some sort of container, which can be as simple as an array. You cannot compose queries, all you get is rows. In other words, they abstract at the wrong level, focusing on rows instead of relations. By applying ideas learned from the functional paradigm, in the code I have been writing queries can be abstracted and composed freely. The system ensures they are sound and will help me fix them if they get out of sync with the DB schema.