[fpc-pascal] Set size limit

[Mark Morgan Lloyd]

Jonas Maebe wrote:

>> Provided that one calls a Z80 16-bit :-) More to the point: do any 
>> current CPUs have e.g. vector operations that suggest a realistic 
>> maximum size?
> 
> The current x86's bit test/set instructions support addressing the 
> complete 32/64 bit address space. But the original 8086 didn't have any 
> vector instructions at all. Again: this limitation is unrelated to 
> instruction sets, it's about deciding on a point at which you're going 
> to waste a lot of memory by using a plain bitmap.

>> For larger sets... OK, how /does/ one declare a set of UTF-8 characters?
> 
> An UTF-8 character is not an ordinal data type and hence support for 
> "set of <utf-8 character>" is orthogonal to support for larger sets. If 
> you store them in strings or arrays, then you need a hashtable of 
> strings or arrays (and/or support for sets of strings or arrays, which 
> would probably be implemented using... a hashtable).

That was pretty much my gist. Since these days Unicode is larger than 
65536 codepoints I don't think there's any advantage to expanding sets 
from 256 to 65536 elements, efficient operations on sparse arrays of 
256-element sets would be far better.

A modest expansion to be able to handle something like a bitboard for Go 
might be attractive though.

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]