You are correct. Moand.Cont yield even runs without -O optimizing, just slower:

Monad.Writer counts 10^9 zeros in 99 seconds (user time)
Monad.Cont counts 10^8 zero in 35 seconds user time.
So the writer is 3.5 times faster without '-O'

With -O
Monad.Writer counts 10^9 zeros in 105 seconds
Monad.Cont counts 10^8 zeros in 11 seconds, 10^9 zeros in 110 seconds.

So with '-O' they are the same speed.  Nice.

Anyone have an idea why ghci can't garbage collect it?
Is this an actual bug or an innate quirk of the REPL ?

--
Chris

On Apr 15, 2005, at 12:43 AM, Cale Gibbard wrote:

However, after compiling with optimisations turned on, there is no
such problem with the continuation-based version, memory usage appears
constant.

 - Cale

On 4/14/05, ChrisK <[EMAIL PROTECTED]> wrote:
Thanks for the Cont example, David.  But...

The MonadCont is clever and it works ... but then fails -- ghci does
not garbage collect and it blows up.
With the MonadCont version I can count up to 10^7 zeros:

*Main> length $ take (10^7) zerosInf
10000000
(26.20 secs, 0 bytes)

But this increases RSIZE of ghc-6.4 to 165MB. The 10^8 version goes to
swap space and I had to kill it. My original MonadWriter version does
not increase RSIZE when run (constant space), so the garbage collection
must be working, and it is O(N) in the # of zeros counted:


*Main> length $ take (10^7) zerosInf
10000000
(1.22 secs, 0 bytes)
*Main> length $ take (10^8) zerosInf
100000000
(10.05 secs, 0 bytes)
*Main> length $ take (10^9) zerosInf
1000000000
(109.83 secs, 6 bytes)

--
Chris


_______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell

Reply via email to