Re: Domains and function arguments

Tom Lane writes:

> Admittedly, we have trouble resolving the type to use when a function is
> overloaded with both a domain and a base type, but that's hardly
> surprising.

Even if you try to work it out, it's going to be a mess. During
resolution, you would have to look inside the data to figure out which
domain, if any, it might fit into. That means that the resolution of an
expression depends on the actual data, not just the structure of the data
(i.e., the data type). Of course, an expression typically needs to be
resolved before the data is plugged in, so this approach cannot work.

If you insist on allowing domains in argument lists, then I think the best
approach is this: For purpose of function resolution, types and all
domains defined over them are equivalent. That would mean, for example,
that if you define positive_int as domain over int, then you cannot define
foofunc(int) and foofunc(positive_int) as the same time.

--
Peter Eisentraut peter_e(at)gmx(dot)net