Magnus Therning wrote:
timeIt times ioa = let
timeOnce = do
t1 <- getCPUTime
a <- ioa
t2 <- getCPUTime
let t = fromIntegral (t2-t1) * 1e-12
return t
in sequence $ take times $ repeat timeOnce
main = do
fh <- openBinaryFile "/dev/urandom" ReadMode
d <- liftM BS.unpack $ BS.hGet fh 100000
t <- timeIt 10 $ return $! B64.encode d
print t
I suspect that it all comes from `B64.encode d` being pure, hence the
encoding happens only once. Now I _really_ want the encoding to
happen 10 times, is there some easy way to achieve this?
A quick answer - not a lot of thought - pass function *and* argument
separately into timeIt ?
timeIt times ioaf ioaarg
.... a <- ioaf ioaarg
As it stands you pass the thunk (B64.encode d) in so it only gets
evaluated once
If you pass the function and argument in then a new thunk is built each
time around
(unless the optimiser nabbles it.......)
/M
[1]: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/timeit
[2]:
--
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Foundations and Methods Research Group Director.
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http://www.cs.tcd.ie/Andrew.Butterfield/
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