[R6RS] Hashing questions

William D Clinger will at ccs.neu.edu
Tue Jun 13 18:13:54 EDT 2006

Kent wrote:
> MIT Scheme had/has something similar; I think it is called object-hash.  I
> don't know about the MIT Scheme mechanism, but the Haskell mechanism is
> implemented internally using---you guessed it---eq? hash tables.  So the
> more primitive mechanism is actually the eq? hash table.

That was true of MIT Scheme as well.  To implement
object-hash, MIT Scheme maintains a global hash table,
which it rehashes after every garbage collection.  MIT
Scheme used a stop-and-copy collector, so collections
were few and far between.

This architecture doesn't make so much sense when the
garbage collector may run hundreds of times a second.


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