Re: [Caml-list] Uncaught exceptions in function type.

[Goswin von Brederlow <goswin-v-b@web.de>]

On Tue, May 27, 2014 at 11:16:18PM +0200, Daniel Bünzli wrote:
> Le mardi, 27 mai 2014 à 08:52, Philippe Veber a écrit :
> > Having no experience on large projects, it is not clear to me why
> > exceptions are considered so dangerous.  
> 
> If you don???t/forget to catch the exception at the right place it
> disrupts your whole call stack, which means that it breaks any
> invariants a correct excecution of your call stack was supposed to
> maintain. Which means that your program state is completely broken and
> you have to exit 1, hoping that you didn???t partially (invariant
> wise) persist anything to disk/network meanwhile.
> 
> Best,
> 
> Daniel

Which is where tracking exceptions in the type of a functions would
come in handy. If you write code that must not be aborted then you
annotate the type to throw no exceptions. The type inference would
then check that that is the case and give you  a compile error
otherwise. That way there couldn't be any surprises of an exception
breaking your call stack.

Also note, even though YOU don't use exceptions doesn't mean some
module you use doesn't. With exception part of a functions type this
would be exposed in the interface and you can deal with it accordingly
(worst case rewrite the module :).

So I think you should be all for having exceptions in the type
especially because you don't like them.

MfG
	Goswin