Re: [Haskell-beginners] Storing the time difference between two Monotonic time results

9 Jul 2018

      Okay, here is what I am trying to do. I am trying to time this mergesort
program. I want to run this program 100, 1000, etc times and store the
timing results in a list if possible. Can't seem to figure out how to do
it! The following program prints the timings to the shell and I need to
figure out a way to store the timings in a list.

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE BangPatterns #-}
import Control.Exception
import Formatting
import Formatting.Clock
import System.Clock
import Control.DeepSeq

mergesort [] = []
mergesort [x] = [x]
mergesort xs = let (lhalf, rhalf) = splitAt (length xs `div` 2) xs
               in merge' (mergesort lhalf) (mergesort rhalf)

merge' lhalf rhalf = merge lhalf rhalf []

merge [] [] acc = reverse acc
merge [] y acc = reverse acc ++ y
merge x [] acc = reverse acc ++ x

merge (l:ls) (r:rs) acc
        | l < r = merge ls (r:rs) (l:acc)
        | otherwise = merge rs (l:ls) (r:acc)

toList :: String -> [Integer]
toList input = read ("[" ++ input ++ "]")

repeater unsortedlist 0 result = return (result)

repeater unsortedlist counter result = do
                            start <- getTime Monotonic
                            evaluate(mergesort unsortedlist)
                            end <- getTime Monotonic
                            fprint (timeSpecs % "\n") start end
                            repeater unsortedlist (counter-1) result

main = do
    file <- getLine
    contents <- readFile file
    let !unsortedlist = (toList contents)
    repeater unsortedlist 100 []

On Mon, Jul 9, 2018 at 3:21 PM, David McBride  wrote:
...
I guess whatever version you are using did not export that function.  In
any case the definition for that function is incredibly simple, so you
could just write your own for now.
diffTimeSpec :: TimeSpec -> TimeSpec -> TimeSpecdiffTimeSpec ts1 ts2 = abs (ts1 - ts2)
On Mon, Jul 9, 2018 at 9:08 AM, Awsaf Rahman 
wrote:
...
I imported the System.Clock module and tried to use the diffTimeSpec
function but it keeps saying "out of scope".
On Mon, Jul 9, 2018 at 2:45 PM, David McBride  wrote:
...
There is a diffTimeSpec function in that module that seems like it
would work.
On Mon, Jul 9, 2018 at 8:30 AM, Awsaf Rahman 
wrote:
...
Hello,
I am trying to time a function I have written in haskell using the
clock package in the following way:
*start <- getTime Monotonic*
*evaluate(something)*
*end <- getTime Monotonic*
*fprint (timeSpecs % "\n") start end*
Now what I want is to store the time difference between *start* and *end.
*Is there a way I can do that?
Regards
Awsaf
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