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Andrei Paskevich authored
- "diverges" states that the computation may not terminate (which does not mean that is always diverges: just as any other effect annotation, this clause states a possibility of a side effect). - "reads {}" states that the computation does not access any variable except those that are listed elsewhere in the specification (or the proper function arguments, if "reads" is in a function spec). - "writes {}" states that the computation does not modify any mutable value. - If a function definition or an abstract computation may diverge, but there is no "diverges" clause in the specification, a warning is produced. If a function definition or an abstract computation always terminates, but there is a "diverges" clause in the spec, an error is produced. - If there is a "reads" or a "writes" clause in a function definition or an abstract computation, then every modified value must be listed in "writes" and every accessed external variable not mentioned in the spec must be listed in "reads". (Notice that this is a stricter requirement than before, when the presence of a "writes" clause did not require to specify "reads".) However, one does not have to write "reads {}" or "writes {}" if the corresponding lists are empty.
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