proper tail calls

Chris Pine chrispi at
Thu Jan 24 11:04:47 PST 2008

Anton van Straaten wrote:
>>> If an annotation is required to achieve proper tail calls, it means 
>>> that you have to be aware of when you're relying on a tail call, and 
>>> remember to use the annotation, or you'll have runtime problems when 
>>> you implicitly rely on tail call behavior that's not there.
>> But this is the case anyway:  you have to be aware of when you're 
>> relying on a tail call that might not actually be a tail call.
> I agree that the situation can occur either way.  An optional 
> annotation, such as Lars recently described, is a fine way to address 
> this: if you know you need a tail call and are unsure of whether you're 
> going to get one, annotate.  But I'm saying that a *required* annotation 
> is undesirable.

Ahhh, I see.  Maybe that part wasn't communicated on-list, but was 
discussed in the trac ticket (or in the phone meeting? can't remember). 
  It was agreed that implementations would always be free to implement 
PTC, and where pages depend on it from one browser, others will have to 
support it there, too.  So, practically speaking, I assumed that it was 
an assertion, not a requirement, and that we would all implement it 
where we could.


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