rust_api_test

DDlog Rust API example

This example demonstrates how to interact with a DDlog program from Rust. It links against the tutorial.dl example and invokes it using the Rust API. The complete workflow is as follows:

              ddlog                                rustc
tutorial.dl ------------> tutorial_ddlog -------+-----------> executable
                                                |
rust_api_test------------------------------------

where tutorial_ddlog is the Rust project generated by the DDlog compiler for the tutorial.dl program. It contains several crates that must be imported by each Rust client. This example (rust_api_test) imports these modules in Cargo.toml and uses them from its main module to create several DDlog transactions.

The generated crates are:

• tutorial_ddlog

  • declares HDDlog type that serves as a reference to a running DDlog program.
  • enum Relations - enumerates program relations
  • several functions that convert between numeric relation id's and symbolic names.

• differential_datalog - contains the DDlog runtime that is the same for all DDlog programs and simply gets copied to each generated DDlog workspace unmodified (this will change in future releases).

• types - contains Rust types that correspond to user-defined DDlog types, one for each typedef and each relation in the DDlog program.

The code is heavily documented and can be used as a tutorial for understanding the API as well as a template for writing your own DDlog clients.

The Rust API is currently not as ergonomic as it should be and will evolve in future releases of DDlog.