What I realised is that neither exception-based approach is appropriate when one wishes to make software as robust as possible. What one needs is to know exactly which errors / exceptions a function can return / raise, and then deal with each on a case-by-case basis. While it is possible that modern IDEs could (indeed, they may well do, for all I know) automatically show you some of the exceptions that a given function can raise, this can only go so far. Theoretically speaking, sub-classing and polymorphism in OO languages means that pre-compiled libraries can not be sure what exceptions a given function call may raise (since subclasses may overload functions, which can then raise different exceptions). From a practical point of view, I suspect that many functions would claim to raise so many different exceptions that the user would be overwhelmed: in contrast, the UNIX functions are very aware that they need to minimise the amount of errors that they return to the user, either by recovering from internal failure, or by grouping errors. I further suspect that many libraries that rely on exception handling would need to be substantially rewritten to reduce the number of exceptions they raise to a reasonable number. Furthermore, it is the caller of a function who needs to determine which errors are minor and can be recovered from, and which cause more fundamental problems, possibly resulting in the program exiting; checked exceptions, by forcing the caller to deal with certain exceptions, miss the point here.

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