https://github.com/rust-lang/datafrog

A lightweight Datalog engine in Rust
https://github.com/rust-lang/datafrog

Last synced: about 1 month ago
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A lightweight Datalog engine in Rust

• Host: GitHub
• URL: https://github.com/rust-lang/datafrog
• Owner: rust-lang
• License: apache-2.0
• Created: 2018-05-16T13:37:32.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2022-01-20T20:23:52.000Z (almost 3 years ago)
• Last Synced: 2024-09-29T22:42:32.471Z (about 2 months ago)
• Language: Rust
• Size: 167 KB
• Stars: 796
• Watchers: 49
• Forks: 44
• Open Issues: 6
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE
  • Code of conduct: CODE_OF_CONDUCT.md

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README

        
# datafrog

Datafrog is a lightweight Datalog engine intended to be embedded in other Rust programs.

Datafrog has no runtime, and relies on you to build and repeatedly apply the update rules.

It tries to help you do this correctly. As an example, here is how you might write a reachability

query using Datafrog (minus the part where we populate the `nodes` and `edges` initial relations).

```rust

extern crate datafrog;

use datafrog::Iteration;

fn main() {

    // Prepare initial values, ..

    let nodes: Vec<(u32,u32)> = vec![

        // ..

    ];

    let edges: Vec<(u32,u32)> = vec![

        // ..

    ];

    // Create a new iteration context, ..

    let mut iteration = Iteration::new();

    // .. some variables, ..

    let nodes_var = iteration.variable::<(u32,u32)>("nodes");

    let edges_var = iteration.variable::<(u32,u32)>("edges");

    // .. load them with some initial values, ..

    nodes_var.insert(nodes.into());

    edges_var.insert(edges.into());

    // .. and then start iterating rules!

    while iteration.changed() {

        // nodes(a,c)  <-  nodes(a,b), edges(b,c)

        nodes_var.from_join(&nodes_var, &edges_var, |_b, &a, &c| (c,a));

    }

    // extract the final results.

    let reachable: Vec<(u32,u32)> = nodes_var.complete();

}

```

If you'd like to read more about how it works, check out [this blog post](https://github.com/frankmcsherry/blog/blob/master/posts/2018-05-19.md).

## Authorship

Datafrog was initially developed by [Frank McSherry][fmc] and was

later transferred to the rust-lang-nursery organization. Thanks Frank!

[fmc]: https://github.com/frankmcsherry