Constraints

Constraints are the foundational components of predicates. They are simply boolean expressions that need to evaluate to True for the predicate they’re part of to be satisfied.

Constraints can be used flexibly:

• A contract may define constraints directly for its state mutation.
• Alternatively, it can apply constraints to state mutations on other contracts, requiring both sets of constraints to be satisfied.

This flexibility enables efficient code reuse. For example, constraints governing a token swap can be deployed once and used across multiple applications. Additionally, users can apply User Data to further restrict the solution space of a predicate, which is covered in-depth in the chapter on User Data and Solutions.