Jon Lang wrote:
What, if anything, is the significance of the fact that pointlike (in
John's example; 'Point' in TSa's counterexample) is generic?

Note that I didn't give a counterexample. I just used different

Here values and types behave very similar. On the value level
you can check 3 + 4 == 7. In a generic addition 3 + $x == 7
you can do two different things. First you can check the truths
for different values of $x or you can *solve* for $x. The latter
also happens in higher order type checks but of course with type
variables. The type system signals an error if it can't find a
suitable solution given the constraints. E.g. on the value level

   my Int $x; $x + $x == 7;

is unsolvable. The same can happen on type level.

Hope that helps, TSa.

"The unavoidable price of reliability is simplicity"  -- C.A.R. Hoare
1 + 2 + 3 + 4 + ... = -1/12  -- Srinivasa Ramanujan

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