statements that could be expressions?

Allen Wirfs-Brock allen at wirfs-brock.com
Wed Jun 1 17:38:01 PDT 2011


On Jun 1, 2011, at 5:22 PM, Brendan Eich wrote:

> On Jun 1, 2011, at 5:16 PM, Mike Samuel wrote:
> 
>> The semantics of all of these are specified in terms of expression
>> semantics.  Every statement or expression is specified in terms of a
>> triple of (one of (normal, throw, break, continue), value, label).
> 
> Alas, only statements have Completion results. Expressions are modeled as having normal completion with a value, and there's a bit of a gap in the spec where a thrown exception unwinds from within an expression to the statement layer.
> 

We probably could rework the spec. so that expression elements also evaluated to Completions and that consumers of them had to explicitly pull out the value. That would make it possible to have a better spec. for exceptions in expressions.  However, I'm not sure it's worth the spec. work.

Allen



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