jabolopes@google.com,
MIME-Version: 1.0
Content-type: text/plain; charset=UTF-8
In-Reply-To:
Even in IO, exceptions should be reserved for truly exceptional conditions (of the "program cannot safely continue" variety), not merely for error checking when this can be described as a normal flow of evaluation. Exceptions are not simply alternative flow of control, even in procedural languages; they are *disruptions* of flow of control.
I think that would be debatable, especially as applied to procedural languages in general. It's very common to use exceptions in routine flow of control in Python programs, if I remember right. Meanwhile, the Haskell library in my opinion somewhat weakens your case by making ordinary conditions into exceptions, for example end-of-file. In the end it's a large grey area. Ideally, what the program has to do, or whether it can even continue at all, is determined by the program using information reported by the function that encounters the error. If there's a good reason why exceptions should be used only when the program won't be able to continue, it must be that the language's exception handling facililty isn't very robust. Donn