DDC compiler and effects; better than Haskell? (was Re: [Haskell-cafe] unsafeDestructiveAssign?)

John A. De Goes john at n-brain.net
Sun Aug 16 09:50:43 EDT 2009

On Aug 15, 2009, at 5:32 PM, Sebastian Sylvan wrote:
> On Sun, Aug 16, 2009 at 12:18 AM, John A. De Goes <john at n-brain.net>  
> wrote:
> You must think I'm arguing for some kind of low-level analog of C,  
> augmented with an effect system. I'm not. You can't do that.
> No, I don't. I think you're arguing for making access to mutable  
> state commutative. Are you not?

There are many cases when mutation to state _is_ commutative. I can't  
argue that certain operations are _always_ commutative without talking  
about the language.

Pretend I'm arguing for a mostly functional language and effect system  
that maximize the opportunities for parallelizing code.

>  I'm not saying you shouldn't parallelise them in very specific  
> circumstances *where it's safe*, I'm just saying that you shouldn't  
> assume that it's safe unless you know it is. If you want to do a  
> transformation that's unsafe in general, but safe in a specific  
> circumstance, then of course, go ahead!
> To my reading it seems like you're arguing that memory/file access  
> should *always* be considered commutative though, which is what I'm  
> objecting too.

In the right language, many times of memory (and possibly file)  
operations _always_ commute. In the wrong language, they _sometimes_  
commute or _never_ provably commute. I'm not arguing for the  
assumption in any language where it is false.


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

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

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