Constraints

Constraints are the business rules that define what makes a good solution. SolverForge uses a constraint streams API — a declarative, composable way to express rules that reads like a pipeline of filters and transformations.

How Constraints Work

1. Select entities or facts from your solution using for_each
2. Filter, join, or group to narrow down the matches
3. Penalize or reward to affect the score
4. Name the constraint with .named()

let factory = ConstraintFactory::<Schedule, HardSoftScore>::new();

factory.for_each(|s: &Schedule| s.shifts.as_slice())    // Select all shifts
    .filter(|s| s.employee_idx.is_none())                // Keep unassigned ones
    .penalize(HardSoftScore::ONE_HARD)                   // Penalize each
    .named("Unassigned shift")                           // Finalize

Constraints are returned as a tuple implementing ConstraintSet<S, Sc>, which the solver evaluates incrementally as it explores moves.

Sections

• Constraint Streams — The core stream API
• Joiners — Combining multiple entity streams
• Collectors — Aggregation functions for group_by
• Score Types — Available score types and when to use each
• Score Analysis — Understanding and explaining scores