Hello Don,
Thursday, August 28, 2008, 10:32:43 AM, you wrote:
> Seems like you can make a pure hashtable by unsafePerformIO on the
> impure one, and exporting only 'lookup'..
probably yes, but it will lose a bit of performance due to incremental
building of hashtable. actually, writing HT module from scratch is
very easy - all we need is a prime searching function (in order to
establish array size). everything else:
data HT a b = HT (a->Int) (Array Int [(a,b)])
create size hash list = HT hashfunc
(accumArray (flip (:))
[]
(0, arrsize-1)
(map (\(a,b) -> (hashfunc a,b)) list)
)
where arrsize = head$ filter (>size)$ iterate (\x->3*x+1) 1
hashfunc a = hash a `mod` arrsize
lookup a (HT hash arr) = List.lookup a (arr!hash a)
--
Best regards,
Bulat mailto:[EMAIL PROTECTED]
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