Module proto_vulcan::operator[−][src]

Expand description

Operators

The signature of operators is different from relations. Operators have different kinds of parameters, of which only OperatorParam and PatternMatchOperatorParam are of interest to user; the parser generates these parameter types for regular operators and pattern-match operators, respectively.

pub struct OperatorParam<'a, U: User, E: Engine<U>, G: AnyGoal<U, E>> {
    pub body: &'a [&'a [G]],
    _phantom: PhantomData<U>,
    _phantom2: PhantomData<E>,
}

// operator <term> {
//    <pattern0> | <pattern1> => <body0/1>,
//    <pattern2> => <body2>,
//    ...
//    _ => <body_default>,
// }
pub struct PatternMatchOperatorParam<'a, U: User, E: Engine<U>, G: AnyGoal<U, E>> {
    // First goal of each arm is the match-goal
    pub arms: &'a [&'a [G]],
    _phantom: PhantomData<U>,
    _phantom2: PhantomData<E>,
}

Even though the structs are identical, the first goal on each arm of PatternMatchOperatorParam is the pattern and the match-term equality.

For example onceo can be implemented as:

extern crate proto_vulcan;
use proto_vulcan::prelude::*;
use proto_vulcan::operator::condu;
use proto_vulcan::operator::OperatorParam;

pub fn onceo<U: User, E: Engine<U>>(param: OperatorParam<U, E, Goal<U, E>>) -> Goal<U, E> {
   let g = proto_vulcan::operator::conj::Conj::from_conjunctions(param.body);
   proto_vulcan!(condu { g })
}