To recap
You claimed a 40ms measurement. If we use `for_` instead of `void $
for` (for reasons mentioned earlier in the thread) and `-O2` when
compiling we get just under 1 ms:
```
time 876.2 μs (852.8 μs .. 896.9 μs)
0.994 R² (0.989 R² .. 0.998 R²)
mean 838.4 μs (825.0 μs .. 855.5 μs)
std dev 48.21 μs (36.91 μs .. 74.18 μs)
variance introduced by outliers: 48% (moderately inflated)
```
Cheers,
Thomas
On Wed, Sep 20, 2017 at 7:27 AM, Станислав Черничкин
I've wrote simple Haskell benchmark program, which populated primitive vector from vector package:
import Data.Vector.Primitive.Mutable as P
vectorBench :: Benchmark vectorBench = bgroup "vector" [ primitive ] where primitive = bgroup "primitive" [ write1M ] where write1M = bench "write1M" $ nfIO $ do v <- P.unsafeNew 1000000 void $ for [0..1000000 - 1] $ flip (P.unsafeWrite v) (1 :: Int) return ()
I use `unsafeNew` to skip memory initialization and `unsafeWrite` to skip boundary checks, I guess it's fastest possible way to write something to vector. My result was about 40 ms.
I wrote similar program in Scala:
for (_ <- 1 to 5) { val start = System.currentTimeMillis() val a = new Array[Long](1000000) for (i <- 0 until 1000000) { a(i) = 1L } val end = System.currentTimeMillis() println(s"${end - start} ms") }
I skip neither boundary checks nor memory initialization, I also used generic array here (suitable for any types of objects, not just for primitive types), so I expected longer run time. But what I got was shocking:
7 ms 3 ms 2 ms 1 ms 2 ms
This program runs 20-40 times faster than Haskell after warm-up. 20-40 times, Carl! Why is Haskell soo slooooow? How can it be?
-- Sincerely, Stanislav Chernichkin.
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