[rust-dev] I would like to remove typestate.

Patrick Walton pwalton at mozilla.com
Fri Jul 13 09:20:23 PDT 2012


On 07/13/2012 09:04 AM, Niko Matsakis wrote:
> Hello Rustics,
>
> Per recent discussions, I would very much like to remove code related to
> typestate. It seems that the current approach is not scaling up to real
> problems. There has been some discussion about alternative,
> lighterweight approaches. I am not opposed to such forward motion.

I agree. I think that a design-by-contract system, which I'm not opposed 
to, will not share any code with the existing typestate system, so 
having that code around is not buying us anything.

> As I said, there are various ways to repair this situation, but given
> that the code is on life support, I'd rather not expend energy fixing
> it. My plan for removal would be to convert all remaining function
> preconditions into assertions. Last time I discussed this on IRC,
> Graydon objected I think because he was concerned that there were
> checks that were being relied upon but which would not be lost. I am
> not sure if converting existing checks into assertions assuages those
> concerns.

What function preconditions remain? My understanding was that there 
weren't any in the Rust compiler and standard libraries...

Patrick


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