The loop macro introduce a special Domain-specific language for iteration consisting of multiple clauses. These clauses can be classified into multiple patterns

• Variables initialization:
  • Once with with,
  • While iterating with for|as,
• Forms evaluation before the iteration with initially,
• Conditional clauses for termination,
• Clauses for evaluating forms with some having specific actions,
• Forms evaluation after the iteration with finally

There are great libraries for doing iterations like SERIES and iterate