[barrkel]

No, lack of static parameterization of the representation of failure is not the problem with checked exceptions. In fact the prison of being forced to construct a tunnel in the (static) type system to carry your error information, irrespective of how dynamic it becomes, is the torture that kills the idea. Errors are fundamentally the leaks in abstractions. They betray the implementation.

The network error that makes a mockery of pretending something is local. The dynamic link error that discloses a pluggable implementation. And all the steps between giving lie to the idea that errors should be caught and handled anywhere near their occurrence - when the only code that knows about the actual final composition is at the top of the stack, far far away, a perilous journey for a fragment of error info - unless such transport is automated, and not gated at customs, as so many checked exceptions boundaries end up being.

I'm in favour of error values for functions that return errors in normal circumstances. But they should be exceedingly easy to dispatch into an unwind mechanism, if it turns out you're not interested. Almost all of the time, the code in the middle doesn't care. Why should it pay the tariff for the transport?

[masklinn]

> The network error that makes a mockery of pretending something is local. […] I'm in favour of error values for functions that return errors in normal circumstances.

Checked exceptions were intended for the latter, and unchecked exceptions for the latter.