OpenAxiom's choice is perfectly rational as far as I can tell.
The only issue would be that Aldor hashing would not equal Spad hashing.
I do not know where hashing is used at the Spad level.
Spad domains are stored in $ConstructorCache, once they are created.
In a newly started session do:
)lisp (gethash '|Fraction| |$ConstructorCache|) ==> nil
then do
a:=1/2
)lisp (gethash '|Fraction| |$ConstructorCache|) ==> ((((|Integer|)) 2 .
#<vector 08beb9f4>))
So spad domains are hashed internally.
I recommend that we follow OpenAxiom's lead on this provided nothing breaks.
Tim
Bill Page wrote:
Tim,
Besides the fact that from the standard we only have that
(equal x y) implies (= (sxhash x) (sxhash y)).
Do you see any reason why SXHASH is not used by default in SetCategory?
Note: OpenAxiom currently defines this default:
add
hash(s : %): SingleInteger == SXHASH(s)$Lisp
Regards,
Bill Page.
On Mon, Nov 9, 2009 at 7:51 PM, Tim Daly <[email protected]> wrote:
...
There is a lisp function to get the hash value of any object
call sxhash. You can call it.
SXHASH(a)$Lisp
Note that if
c:=Integer
then
EQ(a,c)$Lisp is false
SXHASH(a)$Lisp is not equal to SXHASH(c)$Lisp
Thus the hash function you seek already exists.
You just have to accept the fact that Spad is only syntactic
sugar for lisp code and lisp is not evil.
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