[exfascist]

There's a very simple argument for hygiene and convention: The halting problem should make code unreadable, it doesn't largely because of hygiene and the shared knowledge formed by programmer culture. These things restrict the language to something that's just Turing complete and much easier to read.

There is a such thing as legitimately unreadable code, I've had to deal with it. Usually it's abusing things like the blurry line between objects and hashmaps in languages like js and Ruby.

[mcherm]

(1) I understand your point: consistently obeying sensible conventions makes code understandable and maintainable. That's a fairly good argument in favor of consistently using Error for all thrown things.

(2) One unrelated point: I suspect that the halting problem doesn't prove what you think it proves. The halting problem states that one can't build a tool to reliably analyze whether a given piece of code will end or will run forever. Some people seem to believe that this means some code will be "incomprehensible" -- that no code analysis can figure out what it does.

I am quite interested in the question of whether code can be made "incomprehensible" -- it has significance for things like securely protecting source code. But the halting problem would still be true even if "incomprehensible" code obfuscation is impossible and all programs can be "understood". Here's a good example of a program that might or might not halt:

  stop_at = input_number()
   x = 2
   while x < stop_at:
       if is_prime(x) and is_prime(x + 2):
           break
       x += 1

If the twin prime conjecture is true than that program always halts. If the twin prime conjecture is false than that program is an infinite loop whenever its input is larger than the largest twin prime.