RE: [Caml-list] Checked exceptions and type inference

[artboreb@netscape.net (Arturo Borquez)]

Brian Hurt <brian.hurt@qlogic.com> wrote:

>
>Reading LtU I came across this article:
>http://www.octopull.demon.co.uk/java/ExceptionalJava.html
>
>Java treats checked exceptions as part of the type signature of the
>function.  As such, it seems to me that as such, type inference would work
>to propogate most of this information in a more convient way.
>

>From the manual:
Caml provides exceptions for signalling and handling exceptional conditions. ...

These 'exceptional conditions' do not implies an 'error'
at all, so it might be. Moreover exceptions may have a type
within the context where they occurr. ie:

 let x = try String.sub str pos len with _ -> "" in
 ....

in this case failing String.sub is returning a string,
and the type inference system will check it that way.

Perhaps I don't understand what migth be a
'checked exception' in ML. I am missing something?.
can you explain it with an example?

>Checked exceptions actually have their uses, for "errors" which are not
>very exceptional.  Out of memory is highly unexpected.  End of file isn't
>quite as surprising.  Not_found is another that shouldn't be that
>surprising- although that leads to a different religous war.
>
>Is there any research on using checked exceptions in an ML derived
>language?  Any plans/opinions on implementing checked exceptions in Ocaml?
>

Regards.

-- 
Arturo Borquez


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