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From: Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP>
Newsgroups: comp.lang.ada
Subject: Re: Why are Ada compilers difficult to write ?
Date: Mon, 25 Jun 2018 06:04:42 -0000 (UTC)
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Xref: reader02.eternal-september.org comp.lang.ada:53284
Date: 2018-06-25T06:04:42+00:00
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On 2018-06-24, Jacob Sparre Andersen <jacob@jacob-sparre.dk> wrote:
> "Dan'l Miller" <optikos@verizon.net> writes:
>> On Saturday, June 23, 2018 at 12:56:43 AM UTC-5, J-P. Rosen wrote:
>
>>> Well, it is an attempt at making pointers safer, and this is
>>> inherently difficult. Other languages didn't even try...
>>
>> Except Rust nowadays, and hopefully Ada2020 will catch up
>
> The problem with Rust is that the language isn't well specified (a
> "reference implementation" doesn't count as a specification).
>

Especially when that reference implementation keeps changing...

> At Ada-Europe 2018, Maroua Maalej presented a paper with the title "Safe
> Dynamic Memory Management in Ada and SPARK".  It explains how you can
> implement borrowing access types in Ada quite trivially (I had figured
> out the basics myself beforehand).  The challenge is that borrowing
> access types are behaviorally incompatible with existing Ada access
> types, so you have to select the behaviour per access type. - And this
> still doesn't solve all the problems related to anonymous access types
> (i.e. "the heart of darkness").
>

Are anonymous access types a mistake ?

Removing them increases the level of required formality in code but
you can argue either way whether this is a bad thing or not.

Simon.

-- 
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world