A rule set is a named collection of rules and optional nested groups. It implements IRuleSet<T> and is built with RuleSet.For<T>("Name"). Playground: Rule Groups (GroupScenario.cs).

Adding rules

var rules = RuleSet.For<Order>("ApprovalRules")
    .Add(Rule.For<Order>("High amount")
        .When(o => o.Amount > 1000)
        .Then(o => o.RequiresApproval = true)
        .Because("Amount exceeds threshold"));

Groups

Use .AddGroup("GroupName", g => { … }) to nest another RuleSet<T> inside the parent. Groups help organization, scoped execution, and explainability (the tree shows group nodes).

Example:

var mainRuleSet = RuleSet.For<Order>("OrderProcessing")
    .AddGroup("Validation", g => g
        .Add(Rule.For<Order>("Amount check")
            .When(o => o.Amount > 0)
            .Then(o => o.IsValid = true)
            .Because("Order amount is positive")))
    .AddGroup("Shipping Eligibility", g => g
        .Add(Rule.For<Order>("Standard shipping")
            .When(o => o.Amount > 100)
            .Then(o => o.StandardShipping = true)
            .Because("Amount qualifies for shipping")));

Ordering and priority

Rules are ordered by priority (highest first) with stable ordering for equal priorities. Groups are visited according to the engine’s unified pipeline.

Execution options

You can limit which groups run via RuleExecutionOptions<T>.IncludeGroups — see Execution options and ExecutionOptionsScenario.cs.