On Tue, Jul 22, 2014 at 3:44 AM, Matt Rice <[email protected]> wrote:
> On Sun, Jul 20, 2014 at 8:00 PM, Jonathan S. Shapiro <[email protected]> > wrote: > > > This can be viewed as type, or it can be viewed as a known constraint on > a > > value of some type. How do we want to think about this case? > > so it came to mind that 'typestate' is much like a constraint on a > value of some type. > Yes and no. Yes, it's a constraint on the value of some type. The difference between normal constraints and typestate is that the typestate constraint is associated with control flow as well. The "type" assigned to a variable can therefore change as you proceed through the program. You can probably dig up one of the original typestate papers by Rob[ert] Strom and Shaula Yemini. The idea is clearly described, and the papers had usefully illustrative use cases. > and that rust had/removed typestate, after a little looking into it, > it seems they replaced it with 'viewed as a type', in the form of > phantom types with a private constructor... > Is it me, or does Rust seem to be wandering in the weeds these days? I don't track them actively enough to know. Not that I'm in any position to cast nasturtiums at Rust... shap
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