Re: [Chicken-hackers] [PATCH] [CHICKEN 5] Change numerics representations

[Jörg F . Wittenberger]

Am 04.10.2016 um 16:19 schrieb address@hidden:
>> On Tue, Oct 4, 2016 at 4:00 AM, <address@hidden> wrote:
>>
>>>> We could still get rid of the tagged pointer type.  After some more
>>>
>>
>>
>>>> thought on the matter, I believe they're mostly worthless.
>>>
>>> "They" means tagged pointers? I agree.
>>>
>>
>> I continue to disagree.  Tagged pointers make it possible to have
>> dynamically type-safe or type-dispatched treatment of C objects referred to
>> by the pointer side.  Logically it is equivalent to encapsulate the raw
>> pointer in a record, but record dereference is much slower than pointer
>> dereference for whatever reason, so it adds substantial overhead.
> 
> "Substantial" may be a bit strong, though the overhead is indeed there.
> AFAIK, tagged pointers are seldom used. If indeed they were used instead
> of raw pointers everywhere in the FFI (say, by generally tagging each
> pointer of a known type), then the situation would be different, of course.
> 
> I don't feel strong enough to assess this. Any takers?

At least some eggs would break.  However, so far I found only iup among
those I'm using.

/Jörg