Faust 3 is an hypothetical extended version of the Faust programming language algebra allowing to create multi-dimensional block diagrams. The idea behind this project would be to facilitate the implementation of various kind of physical models (musical instruments, electronic circuits, etc.) that often require bidirectional connections. Such a language would especially be ideal to implement complex multidimensional structures such as meshes or feedback delay networks.
Faust 3 is an ongoing project and doesn't exist yet. More information about it can be found in this document.