Skip to main content

Examples

The Policy Engine ships with four runnable example template sets. Each example consists of:

  • a *.template source file (the policy)
  • an *.intent.json input (the user's intent)
  • an *.evidence.json input (the runtime facts)

Each set is self-contained — compile the template, then evaluate against the JSON inputs as shown in Getting Started.

Clothing Purchase​

A retail-style template covering category, audience, size, budget, and optional colour and brand preferences.

Template — clothing_purchase.template​

# A policy template for buying clothes online.
#
# The buyer's intent describes what they want (category, size, audience,
# budget, plus optional color and brand preferences). The evidence
# describes a concrete listing the seller is offering.

name clothing_purchase_guard

intent {
  acceptable_categories: set<string>
  acceptable_colors: optional set<string>
  acceptable_brands: optional set<string>
  size: string
  audience: string
  max_price_cents: int
}

evidence {
  category: string
  color: string
  brand: string
  size: string
  audience: string
  price_cents: int
}

requires {
  evidence.category in intent.acceptable_categories;
  evidence.size == intent.size;
  evidence.audience in {"men", "women", "unisex"};
  evidence.audience == intent.audience;
  evidence.price_cents <= intent.max_price_cents;
  optional: evidence.color in intent.acceptable_colors;
  optional: evidence.brand in intent.acceptable_brands;
}

Intent — clothing_purchase.intent.json​

{
  "acceptable_categories": ["t-shirt", "polo"],
  "acceptable_colors": ["black", "navy", "white"],
  "acceptable_brands": ["Uniqlo", "Hanes", "Lacoste"],
  "size": "M",
  "audience": "men",
  "max_price_cents": 2500
}

Evidence — clothing_purchase.evidence.json​

{
  "category": "t-shirt",
  "color": "navy",
  "brand": "Uniqlo",
  "size": "M",
  "audience": "men",
  "price_cents": 1999
}

Laptop Purchase​

Demonstrates date comparison, chained comparison (8 <= memory_gb <= 32), and grouped boolean logic for refurbished/warranty handling.

Template — laptop_purchase.template​

# A policy template for reviewing a laptop purchase request.
#
name laptop_purchase_guard

intent {
  max_price_cents: int
  latest_delivery: date
  approved_brands: optional set<string>
}

evidence {
  price_cents: int
  delivery_date: date
  brand: string
  seller_country: string
  refurbished: bool
  warranty_months: int
  memory_gb: int
}

requires {
  evidence.price_cents <= intent.max_price_cents;
  evidence.delivery_date <= intent.latest_delivery;
  evidence.seller_country in {"CH", "DE", "FR", "NL"};
  8 <= evidence.memory_gb <= 32;
  (
    not evidence.refurbished
    or evidence.warranty_months >= 12
  );
  optional: evidence.brand in intent.approved_brands;
}

Intent — laptop_purchase.intent.json​

{
  "max_price_cents": 150000,
  "latest_delivery": "2026-12-31",
  "approved_brands": ["Apple", "Lenovo", "Dell"]
}

Evidence — laptop_purchase.evidence.json​

{
  "price_cents": 129900,
  "delivery_date": "2026-05-15",
  "brand": "Lenovo",
  "seller_country": "DE",
  "refurbished": false,
  "warranty_months": 24,
  "memory_gb": 16
}

KYC / Age and Country​

A minimal KYC-style policy: minimum age, allowed countries, and an optional blocklist.

Template — kyc_check.template​

# A minimal KYC / age-verification style policy.
#
# The user declares their constraints in the intent map, the runtime
# presents evidence, and the engine checks conformance.

name kyc_age_and_country

intent {
  min_age: int
  allowed_countries: set<string>
  blocked_countries: optional set<string>
}

evidence {
  age: int
  country: string
}

requires {
  evidence.age >= intent.min_age;
  evidence.country in intent.allowed_countries;
  optional: evidence.country not in intent.blocked_countries;
}

Intent — kyc_check.intent.json​

{
  "min_age": 18,
  "allowed_countries": ["CH", "DE", "FR", "IT"],
  "blocked_countries": ["RU", "BY"]
}

Evidence — kyc_check.evidence.json​

{
  "age": 34,
  "country": "CH"
}

Order Shipment​

Exercises chained comparisons, set superset relations, and grouped boolean logic for premium-SKU thresholds.

Template — order_shipment.template​

# Exercises chained comparisons, arithmetic, and set operations.
#
# "Orders larger than N items must include at least one premium SKU, ship
# within 3 weeks, and route through an approved warehouse."

name order_shipment_check

intent {
  max_items: int
  approved_warehouses: set<string>
  premium_skus: set<string>
  earliest_ship: date
  latest_ship: date
}

evidence {
  item_count: int
  warehouse: string
  ship_date: date
  skus: set<string>
}

requires {
  1 <= evidence.item_count <= intent.max_items;
  evidence.warehouse in intent.approved_warehouses;
  intent.earliest_ship <= evidence.ship_date <= intent.latest_ship;
  (
    evidence.item_count < 10
    or evidence.skus superset of intent.premium_skus
  );
}

Intent — order_shipment.intent.json​

{
  "max_items": 100,
  "approved_warehouses": ["WH-EU-1", "WH-EU-2"],
  "premium_skus": ["SKU-PRIORITY", "SKU-EXPRESS"],
  "earliest_ship": "2026-04-01",
  "latest_ship": "2026-04-30"
}

Evidence — order_shipment.evidence.json​

{
  "item_count": 25,
  "warehouse": "WH-EU-2",
  "ship_date": "2026-04-10",
  "skus": ["SKU-A", "SKU-B", "SKU-PRIORITY", "SKU-EXPRESS"]
}