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

[John A. De Goes]

On Aug 14, 2009, at 9:07 PM, Sebastian Sylvan wrote:

> That's a separate issue. The problem is that if you *do* depend on  
> outside "interference", then the sequence of operations matters.

You're example is highly contrived. Were I designing an effect system,  
I would not design for programs that require outside interference  
through a medium as uncontrolled as the file system, because (1) if  
there are applications requiring such measures, they are few and far  
between, and (2) you cannot make any guarantees about the correctness  
of programs depending on interference through an uncontrolled medium.

Effect system optimizations are about taking programs that are  
correct, and transforming them to faster but equivalent programs that  
are still correct.

That said, your reasoning precludes the use of file read buffering,  
and other similar operations that are routinely done. It's only an  
illusion that such programs are "safe", with or without transformation  
of sequential read operations.

Regards,

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

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