Re: [Caml-list] GC and file descriptors

[Martin Berger <martinb@dcs.qmul.ac.uk>]

> What alternatives are there? 
> 
> One is to  have exception specifications on functions,
> but that is known not to work very well. The first
> difficulty is that once you have them, they must
> become part of the type system. They then 'snowball'
> through the whole program (in the same way 'const'
> does to C programs).

but isn't this snowballing exactly what you want? you can
think of exceptions and normal function returns as well-
behaved value-passing gotos.  but nobody wants to ignore
intermediate types in function chaining. so why should
only the functional but not the exception behaviour be
constraint by types? the only difference between exceptions
and function types is that

* for exceptions, the normal case is that we ignore the exception,
   i.e., all we do is pass it on, without touching it.

* for functions, the normal case is to take the returned value
   and do something with it.

i always wonder if problem would simply disappear with more
expressive typing systems that allow concise specification
of the normal case for exceptions -- where an piece of code is
just a conduit for exceptions -- and appropriate grouping of
exceptions, for example by subtyping.

martin

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