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The Conditional Statement
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A frequent case is that, if a certain condition holds, a specific action should be initiated, otherwise nothing should happen. This could be expressed by an alternative statement with an empty second alternative.

For example, 


   (|  IsBad(Item) Complain(Item) || /*nothing*/ |)
This can be abbreviated by a conditional statement. 

   [|  IsBad(Item) Complain(Item) |]
An alternative statement has the form
  • [| M1 M2 ... Mn |]
The members Mi are elaborated in the given order. If one member fails elaboration is completed and and the conditional statement succeeds. If all members succeed the conditional statement succeeds.

A conditional statement cannot define variables because if one member fails its conceptual empty second case is taken which defines no variables.





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