[R6RS] Enumerations proposal pre-draft
sperber at informatik.uni-tuebingen.de
Sun Apr 23 11:53:19 EDT 2006
William D Clinger <will at ccs.neu.edu> writes:
>> - Having a new type allows for very fast dynamic type checking.
>> Moreover, I suspect that it at least simplifies compile-time
>> checking for compilers that already have the infrastructure for
>> tracking record types through their flow analyses, but not sets of
> I don't see how the speed of run-time type checking would be
> faster with specialized enumeration values than with symbols.
Presumably, you have to go through the list of valid symbols to check
that a given symbol is a member. With a separate type, you just have
to check the tag.
>> - The mapping to integers is much faster than with symbols. This
>> could also be exploited to produce very fast code for a case
>> distinction, via tables or binary search. (This may also be
>> possible for symbols, but I don't see how.)
> Faster, yes, but not much faster.
That depends on the size of the universe, no?
> The speed of set operations is the same with symbols as with
> specialized enumeration values.
Don't you lose a bit at least at construction time, through the
overhead in converting to an integer?
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla
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