[Haskell] Implicit parallel functional programming

Keean Schupke k.schupke at imperial.ac.uk
Thu Jan 20 03:42:34 EST 2005

Ben Lippmeier wrote:

> I thought the "lazy functional languages are great for implicit 
> parallelism" thing died out some time ago - at least as far as running 
> the programs on conventional hardware is concerned.
> Designing an algorithm that breaks apart a "sequential" lazy program 
> into parallel chunks of the appropriate size is **HARD** (with double 
> asterixes). The time and space behavior of a lazy program is complex 
> enough for the _programmer_ to reason about, let alone an automated 
> analysis - which has no knowledge of what the program is actually 
> trying to do.
I guess this is true, but only if you are trying to find the optimal 
solution (or prooveably optimal
solution)... There must me many ad-hoc solutions with reasonable 
performance. Perhaps a good first step would be a solution bounded in 
the worst case by the sequential execution time  (IE the multi-CPU 
version would be no slower than the single CPU version, excluding the 
locking overhead). If something were to win on 2/4/8 cpu machines most 
of the time I think it would
be useful.


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