Boomerang (programming language)

Boomerang is a domain-specific programming language designed for bidirectional transformations, often shortened to "bx." These transformations allow for edits to be propagated between related data sources, maintaining consistency across multiple views of the same underlying information. Boomerang aims to provide a high-level, declarative approach to defining these transformations, abstracting away the complexities of implementing synchronization and conflict resolution.

The core principle behind Boomerang is the definition of a view and a source. A view is a transformed or derived representation of the source data. The language allows programmers to specify how to transform the source into the view (the "forward" transformation) and, crucially, how to propagate changes made to the view back to the source (the "backward" transformation, or update).

Boomerang supports different programming paradigms, often leveraging techniques from functional programming and string manipulation. Its design philosophy emphasizes safety and predictability, aiming to guarantee certain properties about the transformations, such as well-behaved updates and avoidance of data loss. The language relies on concepts like lenses, which are pairs of functions representing the forward and backward transformations, and provides mechanisms for composing these lenses to build more complex transformations.

The practical applications of Boomerang and bidirectional transformations, in general, lie in scenarios where data redundancy is desirable for usability or performance reasons, but consistency across these redundant copies is paramount. Examples include synchronizing data between databases and user interfaces, maintaining consistency between different file formats, or enabling round-trip editing of documents. The challenge in these scenarios is handling situations where changes made to one view might conflict with existing data in other views. Boomerang provides tools and abstractions to manage and resolve these conflicts in a controlled and predictable manner.

The development of Boomerang has involved research into the theoretical foundations of bidirectional transformations, focusing on properties such as invertibility, well-behavedness, and usability. Ongoing research explores extending Boomerang's capabilities to handle more complex data structures and transformation scenarios.