return when desugaring to closures

P T Withington ptw at pobox.com
Tue Oct 14 11:01:58 PDT 2008


On 2008-10-11, at 08:34EDT, David Herman wrote:

> Thank you for pointing out, though, that try/catch isn't so easily  
> defined on top of return-to-label, since it still needs special  
> handling for finally. The options are either to define a lower-level  
> primitive underlying try/finally (akin to Scheme's dynamic-wind), or  
> to leave exceptions -- or at least try/finally -- as primitive. I  
> lean towards the latter; dynamic-wind is a subtle beast.
>
> [For those interested in dynamic-wind, Flatt et al's ICFP 07 paper  
> has a nice investigation into its semantics:http://www.cs.utah.edu/plt/publications/icfp07-fyff.pdf 
> ]

My 2p:  If introducing a lower-level primitive would mean the language  
could someday have handler-binding (the ability to handle a condition  
in the frame it is signaled in), I think that would be a big win.


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