Incremental is a library from Jane Street that gives you a way of building complex computations that can update efficiently in response to their inputs changing, inspired by the work of Umut Acar et. al. on self-adjusting computations.

Incremental can be useful in a number of applications, including: Building large calculations (of the kind you might build into a spreadsheet) that can react efficiently to changing data. Constructing views in GUI applications that can incorporate new data efficiently. Computing derived data while guaranteeing that the derived data stays in sync with the source data, for instance filtering or inversing a mapping.

You can find detailed documentation of the library and how to use it in incremental/src/incremental_intf.ml. You can also find an informal introduction to the library in this blog post and this video.