Crate rslogic [] [src]

Rust Logic

rslogic is a logic programming framework for Rust inspired by µKanren.

A logical statement is built from variables, states, and goals. Create an initial state, then obtain some variables (and resulting state) from it. Construct a goal consisting of variable bindings, logical operations (AND, OR), or predicates. Then evaluate the goal using the state resulting from making the variables. Evaluating a goal returns all possible solutions to the statement, in the form of a number of states containing variable bindings.

use rslogic::state;
use rslogic::state::{Unif, State, PossibleStates};
use rslogic::goal;
use rslogic::goal::{Goal, fail, unify_val, unify_vars, conj, disj, pred};

let s = state::State::<i32>::empty();
let (v1, s) = s.make_var();
let (v2, s) = s.make_var();

let n = 123;
let g = goal::conj(goal::unify_vars(&v1, &v2), goal::unify_val(&v2, n));

let results = g.eval(&s);
assert_eq!(results.len(), 1);
let bound_value = results[0].get(&v1).unwrap();
assert_eq!(bound_value, &n);

This example creates two variables, v1 and v2, and then assembles a logical expression equivalent to (v1 = v2) && (v2 = 123). When evaluated, the resulting state binds 123 to both v1 and v2.