Re: Why are Ada compilers difficult to write ?

[Jacob Sparre Andersen <jacob@jacob-sparre.dk>]

"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).

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").

Greetings,

Jacob
-- 
"Logic, my dear, merely enables one to be wrong with authority!"