Enquiry Clause ¶

Meaning ¶

An enquiry clause is a serial clause in a meek context that doesn’t immediately contain labels, and therefore nor completers. Serial clauses that appear in the enquiry clause can feature labels and completers on their own.

Enquiry clauses (or just “enquiries”) can be found in the following constructions:

• In conditional clauses, the if-part is an enquiry clause that must yield an int.
• In case clauses, the in-part is an enquiry clause that must yield an int.
• In loop clauses, if present, the while-part is an enquiry clause that must yield a bool.
• In conformity clauses, the case-part’ is an enquiry clause that must yield an union.

Early drafts of the language used regular serial clauses in these contexts, which led to an unexpected problem. Consider the following conditional clause:

if int i := x + 10; xxx: i = 0
then ...
else ... i := 0; go to xxx ...
fi

In conditional clauses the if-part introduces a range that is visible in the rest of the clause. In the example above, if x is not zero when the clause is elaborated the else part gets elaborated and jumps back to the if-part. Similar situations happen in case, loop and conformity clauses. To avoid these difficulties, enquiry clauses got introduced with the restrictions explained above.

See Also ¶

• Conditional Clause
• Loop Clause
• Enquiry Clause
• Conformity Clause
• [II 3.2.4.2]
• [II 3.2.4.3]
• [II 3.5.2]
• [II 3.6]