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Model a shipment quote

This small quote sample shows Raven's preferred vocabulary for a domain decision: a record for input data, a union for the possible outcomes, and a plain function for the calculation.

record Shipment(Id: int, Weight: decimal)

union QuoteResult {
    case Quoted(amount: decimal)
    case Rejected(reason: string)
}

func Quote(shipment: Shipment) -> QuoteResult {
    if shipment.Weight <= 0 {
        return .Rejected("Weight must be positive")
    }

    return .Quoted(12.50m + shipment.Weight * 1.75m)
}

What the sample shows

  • Shipment is data with value meaning, so a record is a natural shape.
  • QuoteResult is a closed decision: it is either quoted or rejected, and each outcome carries exactly the data it needs.
  • Quote is an ownerless calculation, so it can remain a plain function rather than becoming a method on a utility class.
  • .Quoted(...) and .Rejected(...) use the function's return type to infer the target union.

The important feature is not terseness. Invalid combinations—such as a rejected quote with an amount but no reason—cannot be constructed through the declared cases.

Continue with records, unions, and classes for the individual type shapes, or domain modeling for larger application design choices.

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