public object GetResult()

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference
  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct an expression
    var query = @"Count($layer)";//count of features in "layer"

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //Provision  values for any profile variables referenced...
    //in our case '$layer'
    var variables = new List<KeyValuePair<string, object>>() {
        new("$layer", featureLayer)
      };
    //evaluate the expression
    try
    {
      var result = arcade.Evaluate(variables).GetResult();
      System.Diagnostics.Debug.WriteLine($"Result: {result}");
    }
    //handle any exceptions
    catch (InvalidProfileVariableException)
    {
      //something wrong with the profile variable specified
      //TODO...
    }
    catch (EvaluationException)
    {
      //something wrong with the query evaluation
      //TODO...
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct an expression
    var query = @"$feature.AreaInAcres * 43560.0";//convert acres to ft 2

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //we are evaluating the expression against all features
    using var rc = featureLayer.Search();

    while (rc.MoveNext())
    {
      //Provision  values for any profile variables referenced...
      //in our case '$feature'
      var variables = new List<KeyValuePair<string, object>>() {
          new("$feature", rc.Current)
        };
      //evaluate the expression (per feature in this case)
      try
      {
        var result = arcade.Evaluate(variables).GetResult();
        var val = ((double)result).ToString("0.0#");
        System.Diagnostics.Debug.WriteLine(
          $"{rc.Current.GetObjectID()} area: {val} ft2");
      }
      //handle any exceptions
      catch (InvalidProfileVariableException)
      {
        //something wrong with the profile variable specified
        //TODO...
      }
      catch (EvaluationException)
      {
        //something wrong with the query evaluation
        //TODO...
      }
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct a query
    var query = new StringBuilder();
    var layer_name = "USA Current Wildfires - Current Incidents";
    //https://developers.arcgis.com/arcade/function-reference/featureset_functions/
    query.AppendLine(
      $"var features = FeatureSetByName($map,'{layer_name}', ['*'], false);");
    query.AppendLine("return Count(features);");

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //Provision  values for any profile variables referenced...
    //in our case '$map'
    var variables = new List<KeyValuePair<string, object>>() {
        new("$map", map)
      };
    //evaluate the expression
    try
    {
      var result = arcade.Evaluate(variables).GetResult();
      System.Diagnostics.Debug.WriteLine($"Result: {result}");
    }
    //handle any exceptions
    catch (InvalidProfileVariableException)
    {
      //something wrong with the profile variable specified
      //TODO...
    }
    catch (EvaluationException)
    {
      //something wrong with the query evaluation
      //TODO...
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct a query
    var query = new StringBuilder();
    //https://developers.arcgis.com/arcade/function-reference/featureset_functions/
    query.AppendLine(
      "var features = Filter($layer, 'DailyAcres is not NULL');");
    query.AppendLine("return Count(features);");

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //Provision  values for any profile variables referenced...
    //in our case '$layer'
    var variables = new List<KeyValuePair<string, object>>() {
        new("$layer", featureLayer)
      };
    //evaluate the expression
    try
    {
      var result = arcade.Evaluate(variables).GetResult();
      System.Diagnostics.Debug.WriteLine($"Result: {result}");
    }
    //handle any exceptions
    catch (InvalidProfileVariableException)
    {
      //something wrong with the profile variable specified
      //TODO...
    }
    catch (EvaluationException)
    {
      //something wrong with the query evaluation
      //TODO...
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct a query
    var query = new StringBuilder();
    //https://developers.arcgis.com/arcade/function-reference/math_functions

    query.AppendLine("var features = Filter($layer, 'DailyAcres is not NULL');");

    query.AppendLine("var count_feat = Count(features);");
    query.AppendLine("var sum_feat = Sum(features, 'DailyAcres');");
    query.AppendLine("var max_feat = Max(features, 'DailyAcres');");
    query.AppendLine("var min_feat = Min(features, 'DailyAcres');");
    query.AppendLine("var avg_feat = Average(features, 'DailyAcres');");

    query.AppendLine("var answer = [count_feat, sum_feat, max_feat, min_feat, avg_feat]");
    query.AppendLine("return Concatenate(answer,'|');");

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //Provision  values for any profile variables referenced...
    //in our case '$layer'
    var variables = new List<KeyValuePair<string, object>>() {
        new("$layer", featureLayer)
      };
    //evaluate the expression
    try
    {
      var result = arcade.Evaluate(variables).GetResult();
      System.Diagnostics.Debug.WriteLine($"Result: {result}");
    }
    //handle any exceptions
    catch (InvalidProfileVariableException)
    {
      //something wrong with the profile variable specified
      //TODO...
    }
    catch (EvaluationException)
    {
      //something wrong with the query evaluation
      //TODO...
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //construct a query
    var query = new StringBuilder();
    //https://developers.arcgis.com/arcade/function-reference/featureset_functions/

    //Assume we have two layers - a polygon and a points layer. 
    //Select all points within the relevant polygon boundaries and sum the count
    query.AppendLine("var results = [];");

    query.AppendLine("var polygons = FeatureSetByName($map, 'PolygonLayerName', ['*'], true);");

    query.AppendLine("var sel_polygons = Filter(polygons, 'IDField IN (2, 15, 16)');");

    query.AppendLine("for(var polygon in sel_polygons) {");
    query.AppendLine("   var name = polygon.Name;");
    query.AppendLine("   var PointsInPolygon = Count(Intersects($layer, Geometry(polygon)));");
    query.AppendLine("   Insert(results, 0, pointsInPolygon);");
    query.AppendLine("   Insert(results, 0, name);");
    query.AppendLine("}");

    query.AppendLine("return Concatenate(results,'|');");

    //construct a CIMExpressionInfo
    var arcade_expr = new CIMExpressionInfo()
    {
      Expression = query.ToString(),
      //Return type can be string, numeric, or default
      //When set to default, add-in is responsible for determining
      //the return type
      ReturnType = ExpressionReturnType.Default
    };

    //Construct an evaluator
    //select the relevant profile - it must support Pro and it must
    //contain any profile variables you are using in your expression.
    //Consult: https://developers.arcgis.com/arcade/profiles/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                            arcade_expr, ArcadeProfile.Popups);
    //Provision  values for any profile variables referenced...
    //in our case '$layer' and '$map'
    List<KeyValuePair<string, object>> variables = [
        new("$layer", pointsLayer),
        new("$map", map)
      ];
    //evaluate the expression
    try
    {
      var result = arcade.Evaluate(variables).GetResult();

      var results = result.ToString().Split('|', StringSplitOptions.None);
      var entries = results.Length / 2;
      int i = 0;
      for (var e = 0; e < entries; e++)
      {
        var name = results[i++];
        var count = results[i++];
        System.Diagnostics.Debug.WriteLine($"'{name}' points count: {count}");
      }
    }
    //handle any exceptions
    catch (InvalidProfileVariableException)
    {
      //something wrong with the profile variable specified
      //TODO...
    }
    catch (EvaluationException)
    {
      //something wrong with the query evaluation
      //TODO...
    }
  }
}

{
  string ArcadeLabelingExpressionName = "My Arcade Label Expression";

  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //Given a layer that has an arcade labeling
    //expression and we evaluate it interactively...
    var def = featureLayer.GetDefinition() as CIMFeatureLayer;
    //Get the label class
    var label_class = def.LabelClasses
                       .FirstOrDefault(lc =>
                       {
                         return lc.Name == ArcadeLabelingExpressionName &&
                                lc.ExpressionEngine == LabelExpressionEngine.Arcade;
                       });
    if (label_class == null)
      return;

    //evaluate the label expression against the features
    var expr_info = new CIMExpressionInfo()
    {
      Expression = label_class.Expression,
      ReturnType = ExpressionReturnType.String
    };

    //https://developers.arcgis.com/arcade/profiles/labeling/
    using var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                                              expr_info, ArcadeProfile.Labeling);
    //loop through the features
    using var rc = featureLayer.Search();
    while (rc.MoveNext())
    {
      var variables = new List<KeyValuePair<string, object>>() {
          new("$feature", rc.Current)
        };
      var result = arcade.Evaluate(variables).GetResult();
      //output
      System.Diagnostics.Debug.WriteLine(
         $"[{rc.Current.GetObjectID()}]: {result}");
    }
  }
}

{
  //Consult https://github.com/Esri/arcade-expressions/ and
  //https://developers.arcgis.com/arcade/ for more examples
  //and arcade reference

  // Note: the following should be embedded in a QueuedTask.Run() statement
  {
    //Assume we have a layer that is using Visual Variable
    //expressions that we want to evaluate interactively...
    var def = featureLayer.GetDefinition() as CIMFeatureLayer;

    //Most all feature renderers have a VisualVariable collection
    var renderer = def.Renderer as CIMUniqueValueRenderer;
    List<CIMVisualVariable> vis_variables = renderer.VisualVariables?.ToList() ??
                          [];
    if (vis_variables.Count == 0)
      return;//there are none
    var vis_var_with_expr = new Dictionary<string, string>();
    //see if any are using expressions
    foreach (var vv in vis_variables)
    {
      if (vv is CIMColorVisualVariable cvv)
      {
        if (!string.IsNullOrEmpty(cvv.ValueExpressionInfo?.Expression))
          vis_var_with_expr.Add("Color", cvv.ValueExpressionInfo?.Expression);
      }
      else if (vv is CIMTransparencyVisualVariable tvv)
      {
        if (!string.IsNullOrEmpty(tvv.ValueExpressionInfo?.Expression))
          vis_var_with_expr.Add("Transparency", tvv.ValueExpressionInfo?.Expression);
      }
      else if (vv is CIMSizeVisualVariable svv)
      {
        if (!string.IsNullOrEmpty(svv.ValueExpressionInfo?.Expression))
          vis_var_with_expr.Add("Outline", svv.ValueExpressionInfo?.Expression);
      }
    }
    if (vis_var_with_expr.Count == 0)
      return;//there aren't any with expressions

    //loop through the features (outer)
    //per feature evaluate each visual variable.... (inner)
    //....
    //the converse is to loop through the expressions (outer)
    //then per feature evaluate the expression (inner)
    using RowCursor rc = featureLayer.Search();
    while (rc.MoveNext())
    {
      foreach (var kvp in vis_var_with_expr)
      {
        var expr_info = new CIMExpressionInfo()
        {
          Expression = kvp.Value,
          ReturnType = ExpressionReturnType.Default
        };
        //per feature eval each expression...
        using ArcadeEvaluator arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
                                    expr_info, ArcadeProfile.Visualization);

        var variables = new List<KeyValuePair<string, object>>() {
            new("$feature", rc.Current)
          };
        //note 2D maps can also have view scale...
        //...if necessary...
        if (mv.ViewingMode == MapViewingMode.Map)
        {
          variables.Add(new("$view.scale", mv.Camera.Scale));
        }
        var result = arcade.Evaluate(variables).GetResult().ToString();
        //output
        System.Diagnostics.Debug.WriteLine(
           $"[{rc.Current.GetObjectID()}] '{kvp.Key}': {result}");
      }
    }
  }
}