Re: [Haskell-cafe] ordNub

In my tests, using unordered-containers was slightly slower than using Ord, although as the number of repeated elements grows unordered-containers appears to have an advantage. I'm sure the relative costs of comparison vs hashing would affect this also. But both are dramatically better than the current nub. Has anyone looked at Bart's patches to see how difficult it would be to apply them (or re-write them)? On Mon, Jul 15, 2013 at 8:43 PM, Clark Gaebel wrote:

Apologies. I was being lazy. Here's a stable version:

import qualified Data.HashSet as S

hashNub :: (Ord a) => [a] -> [a] hashNub l = go S.empty l where go _ [] = [] go s (x:xs) = if x `S.member` s then go s xs else x : go (S.insert x s) xs

Which, again, will probably be faster than the one using Ord, and I can't think of any cases where I'd want the one using Ord instead. I may just not be creative enough, though.

- Clark

On Mon, Jul 15, 2013 at 12:46 AM, Brandon Allbery wrote:

...

On Sun, Jul 14, 2013 at 7:54 AM, Clark Gaebel wrote:

...

Oops sorry I guess my point wasn't clear.

Why ord based when hashable is faster? Then there's no reason this has

to

...

be in base, it can just be a

Did the point about "stable" fly overhead?

-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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