> For a more typical PHP example, getUser(int $id) is not a total function,
> unless you have PHP_MAX_INT user objects defined in your database. If you
> pass an int that does not correspond to a defined user, you now have to deal
> with "user not found" error handling. getUser() is not a total function.
> getUsers(array $criteria), however, arguably is, because it's logical and
> reasonable to map all not-found cases to an empty array/collection, which
> doesn't require any special error handling.
getUser() could return a nullable type. But totality assumes purity,
and I'm assuming you didn't hard-code all users inside the getUser()
function. :) As soon as you interact with the outside world, you can
have exception and errors, and thus you can't guarantee termination.
In any case, I think the concept of totality is pretty foreign to PHP,
and we can probably leave it behind (you'd have to make sure -
statically, in the type-system - there are no infinite recursion, no
infinite loops, ...).
Olle