Function proto_vulcan::relation::succeed

pub fn succeed<U, E, G>() -> InferredGoal<U, E, G> where
    U: User,
    E: Engine<U>,
    G: AnyGoal<U, E>, 

A relation that succeeds.

Proto-vulcan provides a built-in syntax true to avoid the use-clause.

extern crate proto_vulcan;
use proto_vulcan::prelude::*;
fn main() {
    let query = proto_vulcan_query!(|q| {
        conde {
            [true, q == 1],
            [false, q == 2],
        }
    });
    let mut iter = query.run();
    assert!(iter.next().unwrap().q == 1);
    assert!(iter.next().is_none());
}