I did not check the code for 'case ... of ...' constuction in GHC, my
intention comes from the explanations how this construction works in Haskell in
some teaching materials.So, definitely I should do more exploratory work.
Nevertheless, the type signatures and sorting is realized for rather general
situation and can be therefore preferable for some situations.
Best regards,Oleksandr Zhabenko.
субота, 21 вересня 2019 р., 21:07:25 GMT+2, Олександр Жабенко
<[email protected]> написав:
I did not check the code for 'case ... of ...' constuction in GHC, my
intention comes from the explanations how this construction works in Haskell in
some teaching materials.So, definitely I should do more exploratory work.
Nevertheless, the type signatures and sorting is realized for rather general
situation and can be therefore preferable for some situations.
Best regards,Oleksandr Zhabenko.
субота, 21 вересня 2019 р., 20:59:03 GMT+2, [email protected]
<[email protected]> написав:
Yes, you can use IntMap. It needs another dependency and the complexity
choice as O(log (min (n, W))) where W is a number of bits in a representing
key, used for mapping.
For me, it is rather hard to solve whether it can be better, because it raises
another problem of efficient binary representation of the keys.
While working on the topic, I found out that may be the most efficient will be
hashing (for lookup it can be used e. g. Cuckoo hashing) and there is a library
in Haskell for it.Data.HashTable.IO Using it, you can write something like:
{-# LANGUAGE ScopedTypeVariables #-}
module Main where
import qualified Data.HashTable.IO as I
import Data.Maybe (fromJust,isJust)
import System.Environment (getArgs)
main :: IO ()
main = do args <- getArgs let a = [([z,t],x) | x <-
['a'..'d'], z <- ['f'..'t'], t <- ['a'..'p'], [x,z,t] <= "fnf"] b ::
I.CuckooHashTable String Char <- I.fromList a c <- I.lookup b ("kn")
let d1 u = do d <- I.lookup b u print
c if isJust d then putStrLn . show .
fromJust $ d else putStrLn "Nothing"
return () if null args then d1 "fa" else d1 (head
$ args)
|
|
| |
Data.HashTable.IO
|
|
|
so it works. And the library documentation says that a complexity of Cuckoo
hash lookup is about O(1), but with hashing there are questions of ratio of
fulfilling the buckets and collisions.
So, my library having the very generic constraints can be used instead.
Best regards,Oleksandr Zhabenko.
субота, 21 вересня 2019 р., 21:52:18 GMT+3, [email protected]
<[email protected]> написав:
Yes, you can. It needs another dependency and the complexity choice as O(log
(min (n, W))) where W is a number of bits in a representing key, used for
mapping. For me, it is rather hard to solve whether it can be better, because
it raises another problem of efficient binary representation of the keys.
While working on the topic, I found out that may be the most efficient will be
hashing (for lookup it can be used e. g. Cuckoo hashing) and there is a library
in Haskell for it.Data.HashTable.IO Using it, you can write something like:
{-# LANGUAGE ScopedTypeVariables #-}
module Main where
import qualified Data.HashTable.IO as I
import Data.Maybe (fromJust,isJust)
import System.Environment (getArgs)
main :: IO ()
main = do args <- getArgs let a = [([z,t],x) | x <-
['a'..'d'], z <- ['f'..'t'], t <- ['a'..'p'], [x,z,t] <= "fnf"] b ::
I.CuckooHashTable String Char <- I.fromList a c <- I.lookup b ("kn")
let d1 u = do d <- I.lookup b u print
c if isJust d then putStrLn . show .
fromJust $ d else putStrLn "Nothing"
return () if null args then d1 "fa" else d1 (head
$ args)
|
|
| |
Data.HashTable.IO
|
|
|
so it works. And the library documentation says that a complexity of Cuckoo
hash lookup is about O(1), but with hashing there are questions of ratio of
fulfilling the buckets and collisions.
So, my library having the very generic constraints can be used instead.
Best regards,Oleksandr Zhabenko.
субота, 21 вересня 2019 р., 21:34:38 GMT+3, Henning Thielemann
<[email protected]> написав:
On Sat, 21 Sep 2019, olexandr543--- via Haskell wrote:
> My library that can help to optimize using 'case ... of ...' construction if
> there are multiple (more than at
> least 5) variants.
> mm2: The library that can be used for optimization of multiple (Ord a) => a
> -> b transformations
Isn't this a problem you would solve using Data.Map?
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