Proposal to add symbol: "hasInstanceStrict"

Mike Samuel mikesamuel at
Mon Feb 19 16:53:51 UTC 2018

On Mon, Feb 19, 2018 at 11:50 AM, Aleksander Efremov <mr.efrem at>

> In my first example you can found what I mean. There not only function.
> Just instead of that function can be black box results which we must check
> on assignment to const.

Are you referring to the use of PrimitiveNumber in `const c:
PrimitiveNumber = sum(1, 2);` ?
When treating sum as a black box, you can't rely on it to check its
{pre,post}condiitons, so you need an additional guard on the const
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