[Haskell-cafe] Is Haskell IO inherently slower than C?

[Jake]

Thanks for the tip! I tried it again, this time using 100000000, and the
Haskell one runs at around 25 seconds. The C one is only 1.5 seconds. Can
that still be the run time system?

On Wed, May 4, 2016 at 9:18 PM Mike Izbicki <mike at izbicki.me> wrote:

> You need to be doing tests that take much longer to accurately compare
> runtimes of executables.  Here's why:
>
> Haskell programs have a more complicated run time system than C
> programs, and the binaries output by GHC are much larger.  Therefore,
> there will be a small additional overhead that you have to pay once
> when the program starts.  For some machines, this could possibly be on
> the order of 0.3 seconds.
>
> I'd recommend you scale your test so that it takes at least 30 seconds
> for the slowest program.  This will give you more meaningful results.
>
> On Wed, May 4, 2016 at 6:07 PM, Jake <jake.waksbaum at gmail.com> wrote:
> > I also tried the more standard forM_ [0..100000] idiom and got similar
> > times. I hoped loop might be faster, but apparently not.
> >
> > On Wed, May 4, 2016 at 9:05 PM Jake <jake.waksbaum at gmail.com> wrote:
> >>
> >> I'm trying to write a program in Haskell that writes a large file at the
> >> end, and it seems like that output alone is taking way longer than it
> >> should. I don't understand why Haskell shouldn't be able to write data
> as
> >> quickly as C, so I wrote two test files:
> >>
> >> -- Test.hs
> >> import Control.Loop
> >> import Data.ByteString.Builder
> >> import System.IO
> >>
> >> main :: IO ()
> >> main =
> >>   numLoop 0 1000000 $ \_ ->
> >>     hPutBuilder stdout $ char7 ' '
> >>
> >> // test.c
> >> #include <stdio.h>
> >>
> >> int main() {
> >>   int i;
> >>   for (i = 0; i < 1000000; i++) {
> >>     fprintf(stdout, " ");
> >>   }
> >>   return 0;
> >> }
> >>
> >> I compiled them both with -O2, and ran them redirecting their outputs to
> >> /dev/null. For the Haskell version I got times aroudn 0.3 seconds,
> while the
> >> C version was around 0.03. Is there any reason why in simple IO the
> Haskell
> >> version would be slower by an order of magnitude?
> >
> >
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