Function propose

src/runtime/join.ts:395–415

(tripleIndex, prefix)

  // to the prefix if either our args are fully resolved, but our returns aren't.
  // If that's the case, then our proposal will be to fill in our returns.
  propose(tripleIndex, prefix) {
    // if either our inputs aren't resolved or our returns are all filled
    // in, then we don't have anything to propose
    if(!fullyResolved(this.args, prefix)
       || fullyResolved(this.returns, prefix)) return;

     // find out which of our returns we could propose a value for
     let proposed;
     for(let ret of this.returns) {
       if(toValue(ret, prefix) === undefined) {
         proposed = ret;
         break;
       }
     }

     // Each implementation of a constraint has to provide what its potential
     // cardinality will be. Raw constraints like >, for example, will never
     // make a proposal, while something like + might return cardinality 1, and
     // split some approximation.
     return this.getProposal(tripleIndex, proposed, prefix);
  }

  // Constraints accept a prefix if either we're solving for something unrelated,
  // if their args aren't fully resolved yet (we can't compute yet!) or if their