[Haskell-cafe] "computational time" always 0.0 in this example...

[Lennart]

The "time $ evaluate (sum (doTest wordList2 wordList2))"
works fine for me... ...and the ":set +s" is gorgeous as well!

Thanks for the help!

Lennart


Lemmih wrote:
> On 12/7/06, Lennart <lray at l-ray.de> wrote:
>> Hi,
>>
>> with the following code, I want to measure the time being needed to
>> execute the algorithm. But the result is always 0.0.
>>
>> import Char (toLower)
>> import Maybe
>> import List ( delete, sort, intersect )
>> import System.CPUTime
>> import Control.Exception
>>
>> import Debug.Trace
>>
>> fromInt = fromIntegral
>>
>> wordList2 :: [String]
>> wordList2 = ["Sam J Chapman",
>>        "Samuel Chapman",
>>        "S Chapman",
>>        "Samuel John Chapman",
>>            "John Smith",
>>        "Richard Smith",
>>        "aaaa mnop zzzz",
>>        "bbbb mnop yyyy",
>>        "aa mnop zzzzzz",
>>        "a ",
>>        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
>>        "aaaa bcdefgh mmmmmmmm stuvwx zzzzzz",
>>        "jjjj bcdefgh qqqqqqqq stuvx yyyyyy",
>>        "aaaaa bcdefgh stuvwx zzzzzz",
>>        "aaaaa aaaaa aaaaa zzzzzz",
>>        "aaaaa aaaaa"]
>>
>> time :: IO t -> IO t
>> time a = do
>>    start <- getCPUTime
>>    v <- a
>>    end   <- getCPUTime
>>    let diff = (fromIntegral (end - start)) / (10^12)
>> --    let diff = (fromIntegral (end - start))
>>    putStrLn "Computation time:"
>>    print (diff :: Double)
>>    return v
>>
>> main = do
>>         putStrLn "Starting..."
>>         time $ doTest wordList2 wordList2 `seq` return ()
>>         putStrLn "Done."
>>
>> test3 = let loop = getCPUTime >>= print >> loop in loop
>>
>> doTest :: [String] -> [String] -> [ Double ]
>> doTest [] _ = []
>> doTest (x:xs) [] = doTest xs xs
>> doTest (x:xs) (y:ys) = result : (doTest (x:xs) (ys))
>>                         where result =  qGramMetrics2 x y
>>
>> qGramMetrics2:: String -> String -> Double
>> qGramMetrics2 t1 t2 = let i = intersect (qGramList (map toLower t1) 3)
>> (qGramList (map toLower t2) 3)
>>                  il = fromInt (length i)
>>              ml = fromInt ((max (length t1) (length t2)) - 1 )
>>              in (il / ml )
>>
>> -- list of chars within list of qgrams
>> qGramList :: String -> Int -> [[Char]]
>> qGramList [] _        = []
>> qGramList (x:[]) _     = []
>> qGramList (x:xs) i1    = (x: take (i1 - 1) xs):(qGramList xs i1)
>>
>> -- list of chars within list of qgrams
>> numberedQgramListWithStart :: String -> Int -> [(Int, [Char])]
>> numberedQgramListWithStart x i1 = let prefix = replicate (i1-1) '#'
>>                      suffix = replicate (i1-1) '$'
>>                        in numberedQgramList (prefix++(x++suffix)) i1 0
>>
>> numberedQgramList :: String -> Int -> Int -> [(Int, [Char])]
>> numberedQgramList [] _ _    = []
>> numberedQgramList (x:xs) i1 i2
>>            -- add the dollar-sign
>>            | (length xs) < i1 && x=='$'= []
>>            | otherwise = (i2,(x: take (i1 - 1) xs)):(numberedQgramList
>> xs i1 (i2+1))
>>
>> Am using ghci 6.6 under a Kubuntu 6.10 Linux.
>>
>> time $ product [1..1000] `seq` return ()
>> instead of
>> time $ doTest wordList2 wordList2 `seq` return ()
>> works fine.
>>
>> things like
>> time $ print (doTest wordList2 wordList2) `seq` return () or
>> time $ length (doTest wordList2 wordList2) `seq` return () or
>> time $ trace (doTest wordList2 wordList2) `seq` return ()
>> didn't work.
>>
>> Am desperated...
>
> Try:
>> time $ evaluate (sum (doTest wordList2 wordList2))
>