Function canonicalType

lib/infer.js:276–307

(types)

  };

  function canonicalType(types) {
    var arrays = 0, fns = 0, objs = 0, prim = null;
    for (var i = 0; i < types.length; ++i) {
      var tp = types[i];
      if (tp instanceof Arr) ++arrays;
      else if (tp instanceof Fn) ++fns;
      else if (tp instanceof Obj) ++objs;
      else if (tp instanceof Prim) {
        if (prim && tp.name != prim.name) return null;
        prim = tp;
      }
    }
    var kinds = (arrays && 1) + (fns && 1) + (objs && 1) + (prim && 1);
    if (kinds > 1) return null;
    if (prim) return prim;

    var maxScore = 0, maxTp = null;
    for (var i = 0; i < types.length; ++i) {
      var tp = types[i], score = 0;
      if (arrays) {
        score = tp.getProp("<i>").isEmpty() ? 1 : 2;
      } else if (fns) {
        score = 1;
        for (var j = 0; j < tp.args.length; ++j) if (!tp.args[j].isEmpty()) ++score;
        if (!tp.retval.isEmpty()) ++score;
      } else if (objs) {
        score = tp.name ? 100 : 2;
      }
      if (score >= maxScore) { maxScore = score; maxTp = tp; }
    }
    return maxTp;
  }

  // PROPAGATION STRATEGIES