On Thursday 31 January 2008 20:25:41 David Teller wrote:
> What about a generic
>
> type result 'r 'e =
>
>     | Success of 'r  (**The operation was a success*)
>     | Failure of 'e  (**The operation was a failure*)
>
> let purify e =
>     try
>       Success ( Lazy.force e )
>     with
>       exc -> Failure exc
>
> ?
>
> With one such mechanism we can nearly automatically transform
> exception-returning expressions into exceptionless management. We could
> complete this with a trivial amount of Camlp4 code to avoid the call to
> "lazy / Lazy.force".
>
> What do you think about this solution ?

Scrap the explicitly-declared sum type for a polymorphic variant, lazy value 
for a function and catch only a specific exception and you've got the 
approach that I already use.

You can factor this out but this is so rarely used that it isn't worth it. If 
the stdlib had common IO functions I wouldn't use that idiom at all.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/products/?e