NRules / NRules.Language

Business rules language for NRules rules engine.

Rule# - Language for NRules

Rule# (Rule Sharp) is a business rules language for NRules rules engine.

⚠️ This project is currently in early development

Installing Rule#

To compile Rule# rules to the canonical form, get NRules.RuleSharp from nuget via the package manager

> Install-Package NRules.RuleSharp

To compile rules in the canonical form to the runtime model and to be able to execute rules, install NRules.Runtime

> Install-Package NRules.Runtime

Getting Started

In NRules, rules are expressed against a domain model. Given the following domain model (located in the Domain namespace):

namespace Domain;

public class Customer
{
    public string Name { get; set; }
    public bool IsPreferred { get; set; }
}

public class Order
{
    public int Quantity { get; set; }
    public double UnitPrice { get; set; }
    public double PercentDiscount { get; set; }
    public bool IsDiscounted => PercentDiscount > 0;
    public double Price => UnitPrice*Quantity*(1.0 - PercentDiscount/100.0);
}

And given the following rule Discount.rul:

using Domain;

rule "Order Discount"
when
    var customer = Customer(x => x.IsPreferred);
    var order = Order(x => !x.IsDiscounted, x => x.Quantity > 10);
    
then
    order.PercentDiscount = 5.0;
    Console.WriteLine("Applied discount. Customer={0}, Discount={1}", customer.Name, order.PercentDiscount);

The following code will compile the Discount.rul, insert facts into the rules session and fire the activated rules.

var repository = new RuleRepository();
repository.AddNamespace("System");
repository.AddReference(typeof(Console).Assembly);
repository.AddReference(typeof(Order).Assembly);

repository.Load(@"Discount.rul");

var factory = repository.Compile();
var session = factory.CreateSession();

var customer = new Customer {Name = "John Doe", IsPreferred = true};
var order1 = new Order {Quantity = 12, UnitPrice = 10.0};
var order2 = new Order {Quantity = 5, UnitPrice = 15.0};

session.Insert(customer);
session.InsertAll(new[] {order1, order2});

session.Fire();

This prints

Applied discount. Customer=John Doe, Discount=5

Getting Help

Use the following discussion and Q&A platforms to get help with NRules Rule#

• Discussions
• Stack Overflow
• Gitter Chat

Contributing

See Contributor Guide for the guidelines on how to contribute to the project.

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Copyright © 2012-2024 Sergiy Nikolayev under the MIT license.