sclass BodyOfEvidence<Src> {

  // values are: WithProbability(strengthOfEvidence, probabilityOfTheory)

  // will only hold one piece of evidence per src object

  Map<Src, WithProbability<Double>> examples = syncMap();

  double strengthSum, probabilitySum;

  O mutex() { ret examples; }

  double currentProbabilityGuess() {

    synchronized(mutex()) {

      ret doubleRatio(probabilitySum, strengthSum);

    }

  }

  S renderProbabilityGuess() {

    ret "Current probability guess (evidence count " + n2(l(examples)) + "): " + formatDouble3X(currentProbabilityGuess()) + " with strength " + formatDouble3(strengthSum);

  }

  bool hasEvidenceFromSource(Src src) { ret examples.containsKey(src); }

  bool addEvidence(Src src, double probabilityOfTheory, double strengthOfEvidence) {

    synchronized(mutex()) {

      if (hasEvidenceFromSource(src)) false;

      examples.put(src, withProbability(strengthOfEvidence, probabilityOfTheory));

      probabilitySum += probabilityOfTheory*strengthOfEvidence;

      strengthSum += strengthOfEvidence;

      true;

    }

  }

  S toStringWithEvidence() {

    ret toString() + "\n\n"

      + pnlToString(mapToList(examples, (src, e) ->

        (e! == 0.5 ? "     " : e! > 0.5 ? "   PRO" : " CONTRA")

        + ": " + e + " - " + src));

  }

}