On Sun, Dec 6, 2009 at 12:55 AM, Henning Thielemann < lemming@henning-thielemann.de> wrote:
On Sun, 6 Dec 2009, Michael Snoyman wrote:
I think there are plenty of examples like web servers. A text editor with
plugins? I don't want to lose three hours worth of work just because some plugin wasn't written correctly. For many classes of programs, the distinction between error and exception is not only blurred, it's fully irrelevant. Harping on people every time they use error in the "wrong" sense seems unhelpful.
Hope my commenting on this subject doesn't become my own form of *pedantry*.
In an earlier thread I have explained that one can consider a software architecture as divided into levels. What is an error in one level (text editor plugin, web server thread, operating system process) is an exception in the next higher level (text editor, web server, shell respectively). This doesn't reduce the importance to distinguish between errors and exceptions within one level. All approaches so far that I have seen in Haskell just mix exceptions and errors in an arbitrary way.
I think we can all appreciate why it would be a bad thing is we treat exceptions as errors. For example, I don't want my program to crash on a file not found. On the other hand, what's so bad about treating errors as exceptions? If instead of the program crashing on an array-out-of-bound or pattern-match it throws an exception which can be caught, so what? Michael