Re: [Chicken-hackers] [PATCH] Flow-analysis enhancement for assigned variables

[Alaric Snell-Pym]

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On 01/30/2012 11:31 AM, Felix wrote:

> I just mention this to show that there are quite a few ways to "work
> around" the assumptions made by the type system, both applying to
> variables and data. Concurrently performing side effects makes all
> analysis moot. In the absolute worst case, one has to disable
> specialization and ignore warnings produced by the scrutinizer.

The ability to concurrently mutate arbitrary state is rarely useful (it
tends to introduce more bugs than features!), and causes a lot of
trouble for implementers. Non-concurrently mutating arbitrary state is
bad enough, too!

This is why I'm hoping that future Scheme Reports can do more to
constrain mutation - immutable cons cells by default (with mutable ones
still available for backwards compatability), for instance. Plain set!
isn't too bad, as there's no way to pass references around in Scheme, so
you can always lexically analyse it, but being able to mutate the
internals of arbitrary data structures can be a pain.

ABS

- --
Alaric Snell-Pym
http://www.snell-pym.org.uk/alaric/
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