Module expression 

Iterative expression evaluation

Evaluates expressions without recursion using a stack-based approach. All runtime errors (division by zero, etc.) result in Veto instead of errors.

Functions

evaluate_rule

Evaluate a rule to produce its final result and proof. After planning, evaluation is guaranteed to complete — this function never returns a LemmaError. It produces an OperationResult (Value or Veto) and a Proof tree.