code: function sc_makePromise(proc) {
      var isResultReady = false;
      var result = undefined;
      return function() {
  	if (!isResultReady) {
  	    var tmp = proc();
  	    if (!isResultReady) {
  		isResultReady = true;
  		result = tmp;
  	    }
  	}
  	return result;
      };
  }
docs: * META ((export #t))