[Haskell-cafe] Re: DDC compiler and effects; better than Haskell?

John A. De Goes john at n-brain.net
Sun Aug 16 09:38:36 EDT 2009

I chose this example specifically because parsing/compiling is not IO- 
bound. Many build systems today achieve multi-core scaling by  
parallelizing all the phases: parsing, semantic analysis, and  

Your question is a good one and one we face already in auto- 
parallelization of purely functional code: how do you know when the  
cost of doing something in another thread is overwhelmed by the  
benefit? I think JIT compilation provides the ultimate answer to these  
types of questions, because you can make guesses, and if you get them  
wrong, simply try again.


John A. De Goes
N-Brain, Inc.
The Evolution of Collaboration

http://www.n-brain.net    |    877-376-2724 x 101

On Aug 16, 2009, at 2:46 AM, Marcin Kosiba wrote:
>> Hi,
> 	IMHO, provided with a flexible effect system, the decision on how  
> to do
> read/write operations on files is a matter of libraries.
> 	But I'd like to ask another question: is the effects system you're  
> discussing
> now really capable of providing significant performance improvements  
> in case
> of file I/O? Even if we assume some consistency model and transform  
> one
> correct program to another one -- how do you estimate efficiency  
> without
> knowledge of physical media characteristics? I kinda see how this  
> could be
> used to optimize different kinds of media access (reordering socket/ 
> file
> operations or even running some of those in parallel), but I don't  
> see how
> can we benefit from reordering writes to the same media.
> 	Another thing is that not every kind of r/w operation requires the  
> same
> consistency model -- like when I'm writing a backup for later use I  
> only care
> about my writes being in the same order. I imagine that such an  
> effect system
> could help write software for CC-NUMA architectures or shared-memory
> distributed systems.
> -- 
> Thanks!
> 	Marcin Kosiba
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