Proposal to add symbol: "hasInstanceStrict"

T.J. Crowder tj.crowder at
Tue Feb 20 18:20:26 UTC 2018

On Tue, Feb 20, 2018 at 6:05 PM, Mike Samuel <mikesamuel at> wrote:
> I'm probably just going to echo themes that T.J. has dealt with better,

Quite the opposite.

And keying off Mike's excellent summary: I like the idea of providing a
means of handling preconditions (and postconditions), of which runtime type
checking is one example but only one. I'd just prefer to see it as a
general mechanism than type-checking specifically.

I suggest getting deep into the decorators stuff and helping push it
forward, possibly into areas where it hasn't previously been headed (such
as your `let x = sum(y, y)` where you want to have runtime type checking on
what gets assigned to `x` -- as far as I know, that isn't even on their
radar). Basically that's applying a precondition to the assignment to `x`
(or a postcondition on the call to `sum`). Which could be interesting. You
may or may not get agreement on pushing forward that far, but if you feel
strongly about the functionality you're after, I see that as the direction
to pursue. (Not that I'm in ANY way any kind of authority on moving things
through the process here. Not remotely.)

-- T.J. Crowder
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