then nominal will be? :) On Tue, Sep 25, 2012 at 3:37 PM, Andreas Rossberg <[email protected]>wrote:
> On 25 September 2012 15:31, Andrea Giammarchi > <[email protected]> wrote: > > That's a hell of a question ... shapes speaking I'd say structural, since > > AFAIK shapes are those boosted up more, isn't it? > > > > That would solve String VS string and Array VS Arguments which is, I > > believe, kinda desired. > > > > Which one would you chose ? > > I assume that most people would probably prefer structural types in > principle, but the problem is that they induce far, far more expensive > runtime checking (easily an order of magnitude). Which is why guards > and trademarks were proposed as a more conservative, nominal > mechanism. > > Generally speaking, retrofitting something type-like on an untyped > language is a *very* hard problem. It has been tried with many > languages and has succeeded for very, very few. You can read lots and > lots of research papers on the subject. > > Fortunately, though, we have top-notch expertise on that topic on > TC39, e.g. Sam TH. ;) > > /Andreas >
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