Re: [Caml-list] Scoped Bound Resource Management just for C++?

[Florian Weimer <fw@deneb.enyo.de>]

* Andreas Rossberg:

> On Feb 9, 2011, at 20.11 h, Florian Weimer wrote:
>
>>> Scope-bound resource management is inherently broken, at least
>>> without sophisticated type system support.
>>
>> If the environment supports communicating processes with separate
>> execution pointers, it is straightforward to bypass restrictions, no
>> matter how evolved the type system is.
>
> I don't know what scenario you have in mind with "separate execution
> pointers". In principle, I'm pretty certain that you could always
> define some suitable (e.g. linear) type system, if your language was
> sufficiently well-behaved.

If you have coroutines or threads with communication among them, you
can always turn type-enforced region-based handles into open handles
with an explicit close operation.

>>> 2) or it is unsafe, i.e. you can access an object after its life
>>> time has
>>> ended, with potentially desastrous effects.
>>
>> This can be made safe with type-safe memory and run-time checks.  I
>> don't think this is a good excuse.
>
> True, runtime checks can deal with some of the "disastrous effects",
> but they cannot make it safe in a broader sense (e.g., type-safe in an
> interesting way), and AFAICS don't apply to memory itself as a
> resource.

Like array bounds checking, integer division or other partial
functions. 8-)

> You may argue that that is good enough, but then again, you can
> already achieve that level of assurance using higher-order
> functions.

This is mostly about syntax.  There is already a very convenient
notation, but it has a resource leak.