How can I go about getting a program\'s running time through system time functions in Haskell? I would like to measure the execution time of a whole program and/or an individual
I'm not sure how accurate it is, but using :set +s
in ghci will show the time and space used for subsequent computations.
:set +s
is really neat if use ghci, otherwise you can use Criterion.Measurement
, see my answer to another question with example.
1) If you want to benchmark something, use the criterion package.
2) If you want to time a function and are positive you have controlled for laziness as needed, then just use Data.Time.getCurrentTime
from the time package.:
import Data.Time
...
start <- getCurrentTime
runOperation
stop <- getCurrentTime
print $ diffUTCTime stop start
A slicker packaging of the above pattern can be found in the timeit package.
3) If you actually want the running time of a program that just happens to be written in Haskell then use your systems time
utility. For most POSIX systems (Mac, Linux) just run:
$ time ./SomeProgram
And it will report user, wall, and system time.
Assuming you don't just want to measure the total running time of your program, like so:
$ time ./A
Then you can time a computation a number of ways in Haskell:
For more statistically sound measurement, consider
Finally, in all cases, you need to think about lazy evaluation: do you want to measure the cost of fully evaluating whatever data you produce, or just to its outermost constructor?