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[Caml-list] Catching exceptions into strings
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Date: -- (:)
From: Xavier Leroy <xavier.leroy@i...>
Subject: Re: [Caml-list] Catching exceptions into strings
> That's really rather surprising.  Given that the manual recommends that
> users explicitly check for zero to avoid this exception

The manual suggests that instead of writing

        try x / y with Division_by_zero -> ...

you could also write

        if y = 0 then ... else x / y

and not only avoid the issue, but end up with clearer code as well.
However, this kind of transformation isn't always applicable.

> , why isn't the
> compiler simply inserting the check for them

This is a reasonable option -- much more reasonable than trying to
intercept the SIGFPE signal and somehow turn it into an exception.
I still have doubts that reporting division by zero via an exception
is really useful, though.

> where it happens to be necessary, and optimizing it out when it is not?

I'm more skeptical here.  I'm yet to see a practical compile-time
analysis that can prove that an integer expression is not zero in any
but the most trivial cases (the expression is a constant or a for-loop
index). (By "integer", I mean machine integers with modulo arithmetic.)

- Xavier Leroy
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