rust-rule-engine 1.20.1

A blazing-fast Rust rule engine with RETE algorithm, backward chaining inference, and GRL (Grule Rule Language) syntax. Features: forward/backward chaining, pattern matching, unification, O(1) rule indexing, TMS, expression evaluation, method calls, streaming with Redis state backend, watermarking, and custom functions. Production-ready for business rules, expert systems, real-time stream processing, and decision automation.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

// Advanced rules with nested conditions and multiple operators

rule "Premium Customer Benefits" salience 20 {
    when
        ((user.vipLevel >= 5) && (user.totalSpent > 10000)) || 
        ((user.membershipYears >= 3) && (user.loyaltyPoints > 5000))
    then
        apply_discount(25);
        set(user.freeShipping, true);
        add_loyalty_points(500);
}

rule "Holiday Season Special" salience 15 {
    when
        ((date.month == 12) && (date.day >= 20)) && 
        ((order.amount > 200) || (user.hasGiftCard == true))
    then
        apply_discount(15);
        set(order.giftWrap, true);
        log("Holiday special applied");
}

rule "Flash Sale Eligibility" salience 12 {
    when
        (product.category == "electronics") && 
        ((user.notificationPrefs == "all") || (user.notificationPrefs == "sales")) &&
        (product.stock > 10)
    then
        send_notification("flash_sale");
        set(product.flashSaleEligible, true);
}