[Haskell] Control.Monad.Writer as Python generator

[Cale Gibbard]

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 <chrisk at mit.edu> 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
>