[SystemSafety] A small taste of what we're up against

[Peter Bishop]

Unambiguous semantics is certainly a good thing, but it is not the whole
story.

It certainly helps to avoid (or detect) certain coding bugs, but a
program with defined semantics could still be written in a totally
opaque way (e.g. meaningless variables, poor layout,no comments, etc)
that would totally defy manual inspection.

So the other part of the story is having a "easy-to-read" program
structure and coding style
- this is not language-specific but very important if we want to help a
reviewer see what it does and more importantly what it doesn't do
functionally.

Another area that (most) languages do not address is concurrency, so
Pascal might be better than C semantically *as a sequential program* but
both are equally vulnerable to data races in a concurrent real-time
environment, i.e. the behaviour is semantically ambiguous unless other
concurrency control measures (outside the language semantics) are put in
place.

Peter Bishop

On 24/10/2018 11:23, Coq, Thierry wrote:
> I request the "easy-to-read" semantics for four reasons:
> - it increases the productivity and reduces the introduction of defects in the sources. I read somewhere that 90% of the developer's time was spent reading source, and only 10% writing sources, but I cannot find the reference,
> - it adds a lot of value and there is a big reduction in defects when the customer is able to read the sources, and make comments,
> - peer reviews and inspections within the team also provide a great value in reducing defects that cannot be found otherwise, and easy-to-read languages have a great advantage in that area.
> - the systems we build are long lived and the original developers have gone long ago, when maintenance/upgrades have to be performed. Again, easy-to-read languages provide a great advantage.
>
> I would define "easy-to-read" as "as close to unambiguous English as possible".

-- 
Peter Bishop
Chief Scientist
Adelard LLP
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