Control Structures

So far, rules were the only mechanism for describing decisions. When two cases had to be described, two different rules were required. When a local decision was necessary inside a rule body, a new predicate was introduced to handle this.

In this section, we introduce further constructs to deal with decisions.

• The Alternative Statement
  
• Dataflow
  
• The Predicate where
  
• Disjunctions
  
• The Conditional Statement
  
• Using Alternative and Conditional Statements