Function canrun::goals::project::assert_1

pub fn assert_1<'a, A, AV, D, F>(a: AV, func: F) -> Goal<'a, D> where
    A: Debug + 'a,
    AV: IntoVal<A>,
    D: DomainType<'a, A>,
    F: Fn(&A) -> bool + 'a, 

Create a projection goal that succeeds if the resolved value passes an assertion test.

use canrun::{Goal, both, unify, var, assert_1};
use canrun::example::I32;

let x = var();
let goal: Goal<I32> = both(unify(1, x), assert_1(x, |x| *x < 2));
let result: Vec<_> = goal.query(x).collect();
assert_eq!(result, vec![1])