[Swift-devel] Swift user guide

[Ben Clifford]

On Sun, 1 Mar 2009, Ian Foster wrote:

> 2) Arrays: I gather from below that the size of an array is defined by
> assignments to it. This seems confusing and dangerous to me: doesn't it
> require a global analysis, which must ultimately be undecidable, to determine
> whether an array is closed?

yes.

They're a very unpleasant structure at the moment. As I've written in 
other mails in more depth, I'd prefer to see them behave as 
single-assignment structures constructued by something like looks similar 
to but slightly different to the present loop constructs, so that you'd 
say:

  array = foreach ....

rather than

  foreach ... {
     array[i]=...
  }

There would be no requirement for this to actually execute as some atomic 
operation, and could happen over time interleaved with other tasks, as 
happens for foreach at the moment; but from a code analysis perspective, 
its much clearer when the array is closed - after the single statement 
that assigns to it has fully completed, like non-array variables.

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