Basic array processing

main.cpp

#include <vector>
#include <time.h>

extern "C" double getCPUTime();

using namespace std;

int main(int argc, char** argv) {
  const int numReps = 10000;
  const int n = 1000000;
  vector<int64_t> v;
  for(int i = 0; i < n; ++i) {
    v.push_back(i);
  }
  double startTime, endTime;
  startTime = getCPUTime();
  int64_t s;
  for(int rep = 0; rep < numReps; ++rep) {
    s = 0;
    for(int i = 0; i < n; ++i) {
      int64_t x = v[i] + 5;
      if(x < 10) s += x;
    }
  }
  endTime = getCPUTime();
  printf("Mapping, filtering, and summing took: %.3fms\n", 
         1000 * ((endTime - startTime) / (double)numReps));
  printf("The answer was %lld, btw\n", s);
  return 0;
}

Main.hs

import Criterion.Main
import qualified Data.Vector.Unboxed as V

go :: V.Vector Int -> Int
go = V.sum . V.filter (< 10) . V.map (+ 5)

main :: IO ()
main = do defaultMain [ bench "mapFilterSum" $ whnf go v ]
          putStrLn $ "The answer was " ++ show (go v) ++ ", btw"
  where v = V.generate n id
        n = 1000000

results

$ make
clang -O3 -c getCPUTime.c
clang++ -O3 main.cpp getCPUTime.o
$ ./a.out
Mapping, filtering, and summing took: 1.490ms
The answer was 35, btw
$ cabal run
Preprocessing executable 'DumbBench' for DumbBench-0.1.0.0...
Running DumbBench...
benchmarking mapFilterSum
time                 1.510 ms   (1.493 ms .. 1.525 ms)
                     0.999 R²   (0.998 R² .. 0.999 R²)
mean                 1.519 ms   (1.504 ms .. 1.535 ms)
std dev              53.07 μs   (42.71 μs .. 69.47 μs)
variance introduced by outliers: 23% (moderately inflated)

The answer was 35, btw