proto-vulcan

A miniKanren-family relational logic programming language embedded in Rust.

In addition to core miniKanren language, proto-vulcan currently provides support for:

• Disequality constraints CLP(Tree)
• Finite-domain constraints CLP(FD)
• Various operators: anyo, conda, condu, onceo, project
• Writing goals in Rust embedded inline within proto-vulcan
• User extension interface

The language is embedded into Rust with macros which parse the language syntax and convert it into Rust. For parsing the language syntax, it uses the tt-call library.

Due to heavy macro-usage, the default recursion limit is not sufficient. It can be increased with:

#![recursion_limit = "512"]

Example

#![recursion_limit = "512"]
extern crate proto_vulcan;
use proto_vulcan::*;

fn main() {
    let query = proto_vulcan_query!(|q| {
        conde {
            q == 1,
            q == 2,
            q == 3,
        }
    });

    for result in query.run() {
        println!("q = {}", result.q);
    }
}

The example program produces three solutions:

q = 1
q = 2
q = 3

New relations can be defined as Rust-functions using proto_vulcan!-macro.

use proto_vulcan::*;
use proto_vulcan::relation::emptyo;
use proto_vulcan::relation::conso;
use std::rc::Rc;

pub fn appendo<U: UserState>(l: &Rc<LTerm>, s: &Rc<LTerm>, ls: &Rc<LTerm>) -> Rc<dyn Goal<U>> {
    let s = Rc::clone(s);
    proto_vulcan!(
        conde {
            [s == ls, emptyo(l)],
            |a, d, res| {
                conso(a, d, l),
                conso(a, res, ls),
                closure {
                    appendo(d, s, res)
                }
            }
        }
    )
}

More examples in documentation.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.