[Shootout-list] haskell lists

[Aaron Denney]

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Hi.  I've noticed that the list processing benchmark for Haskell is
listed as "Test Implemented but not measured (timeout or error)."

I believe this is because the code reads the size parameter from
standard input instead of from the command line:

do s <- getLine

Adding
import System(getArgs)
and changing that line to
do ~[s] <- getArgs

It's also ridiculously inefficient.  I've attached a much faster
implementation that relies on the "Edison" libraries that come with
GHC to use lists that can be efficiently manipulated at either end.

-- 
Aaron Denney
-><-

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-- uses the edison library.
-- ghc -O2 -package data

module Main(main) where
import System(getArgs)
import qualified BankersQueue as L

copy = fmap id

test :: Int -> Int
test size | isok1 && isok2 = L.size l1'
          | otherwise = error "not OK"
                  where l1 = L.fromList [1..size] 
                        l2 = copy l1
                        l3 = L.foldl (L.snoc) L.empty l2
                        l2' = L.foldr (flip L.snoc) L.empty l3
                        l1' = L.reverse l1
                        isok1 = L.lhead l1' == size
                        isok2 = l1' == l2'
  
main = do ~[s] <- getArgs
          putStrLn . show . test . read $ s

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