On 21/07/2014 1:00 pm, "Jonathan S. Shapiro" <[email protected]> wrote: > > On Wed, Jul 16, 2014 at 2:12 PM, Matt Rice <[email protected]> wrote: >> >> I think the best argument for it I have come up with is something like >> the following scenerio: >> >> we have a structure Triangle {pt1; pt2; pt3;} >> we have a structure much like a subtyping relationship with restricted values >> structure RightTriangle {pt1; pt2; pt3} where one of the angles must >> be 90 degrees, and for whatever reason we wish not to make >> RightTriangle opaque, to avoid the indirection of accessor functions >> for the values, > > > OK. This is an interesting example. The example itself is clearly contrived, but it illustrates a problem that actually does arise in practice, which is data structure instances that meet some interesting constraint. In this case the right-angle constraint. > > 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? > > Incidentally, this is the kind of think that preconditions, postconditions, and assertions deal with quite well. >
I think this is what Matt means by Curry types. There seems to be a lot of literature in that area; it seems it will take a while before I have even a feeling for what will scale and what will be pleasant. > > shap > > _______________________________________________ > bitc-dev mailing list > [email protected] > http://www.coyotos.org/mailman/listinfo/bitc-dev >
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