[r6rs-discuss] Hash function return value constraints
owinebar at gmail.com
Fri Apr 3 20:43:09 EDT 2009
On Fri, Apr 3, 2009 at 5:16 PM, leppie <xacc.ide at gmail.com> wrote:
> ----- Original Message -----
> From: "Brian Harvey" <bh at eecs.berkeley.edu>
> > Okay, I'm confused, A hash value is an index into an array. If the
> > hash value doesn't fit in a fixnum, then the array doesn't fit in memory,
> > or even in the virtual address space (by a factor of 4 on a 32-bit
> > machine).
> > What am I missing here?
> Something other than the most extreme naive implementation of a hashtable,
> ever. :)
I'm with Brian - I haven't been following the "hash table" literature, but
to the best of my knowledge its normal usage refers specifically to
associations recorded in an array. Maybe the term has acquired a wider
meaning - certainly R6RS does not retain this standard meaning - but I think
it's hard to claim the standard definition of X is "the most extreme naive
implementation of " X.
It's up to the implementation to choose how it converts the hash value into
> a meaningful index (or perhaps something else).
If both R6RS conformance and the extra bit is so important, why not add a
special unsigned fixnum to your internal data types?
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