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From: Shawn Walker <binarycrusader@gmail.com>
Date: Sat, 4 Jul 2020 14:28:33 -0700
Message-ID: <CAAhSavaeVt1psk4=pbFF-zGcp288Xm9VG3B8fr19Y_O1P-25XA@mail.gmail.com>
Subject: Re: unexpected behavior with arrays?
To: Westerbly Snaydley <westerbly@gmail.com>
Cc: ~duangle/scopes@lists.sr.ht
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On Sat, 4 Jul 2020 at 12:49, Westerbly Snaydley <westerbly@gmail.com> wrote=
:
> On Sat, Jul 4, 2020 at 12:34, Shawn Walker <binarycrusader@gmail.com>
> wrote:
> > I guess I=E2=80=99m spoiled by the rust compiler=E2=80=99s reasoning ab=
out
> > lifetimes.  If I try to use =E2=80=98x=E2=80=99 once the binding has ex=
pired it
> > won=E2=80=99t let me and tells me why.  Here it seems like Scopes shoul=
d
> > know the lifetime of the storage and then could prevent or warn about
> > further use.
>
> Scopes' borrow checker is opt-in, and the core is designed such that
> lower level constructs / APIs are not checked. The higher level APIs on

So if I'm guessing correctly, the borrow checker you're referring to
is the "view propagation" mechanism?  However, that can't be used with
the lower-level constructs and some of the APIs?

> the other hand are built on top of those but with security added in. In
> this particular example, it's usually recommended to use the Array
> (from Array.sc) data-type instead, which is both bounds and lifetime
> checked. Similarly alloca, malloc shouldn't be used directly (ie. use
> `local` with a unique type, or a Box<T> for heap).

I was trying to puzzle out the subtleties between let, local, etc.
using examples from the tests.  The documentation and test examples
made it clear enough that local was stack, global was heap, etc. but
let is still murky to me.  My understanding is that let is generally
register-based allocation for values unless you use something like
alloca-x but maybe it's stack too?

--=20
Shawn Walker-Salas