Re: Build language with weak typing, then add scaffolding later to strengthen it?

["J-P. Rosen" <rosen@adalog.fr>]

Le 26/05/2015 10:01, Sylvain Laperche a écrit :
> On 2015-05-25, Peter Chapin <PChapin@vtc.vsc.edu> wrote:
>> I haven't read the Oberon Report but I can't help but wonder if
>> it's leaving out a lot.
> 
> For a simple exemple: what happen when an integer overflow? - The
> program aborts? - The value silently wrap-around (2-complement
> behavior)? - Is it an undefined behavior (like in C)?
> 
> Another one: what happens when there is an access out of the bounds
> of an array? A crash? A runtime check? undefined behavior (like C)?
> 
> I did not find the answer in these 17 pages. It seems that it leaving
> out a lot indeed…
> 
I also downloaded the Oberon report and had a look at it (easy, only 17
pages). I'd say it is not to be compared with anything close to a
standard. It's just a "report" that gives a vague idea of the language
without addressing any serious issue. TBH, it claims that its fuzzy
definitions are intended:

"What remains unsaid is mostly left so intentionally, either because it
is derivable from stated rules of the language, or because it would
unnecessarily restrict the freedom of implementors."

Translate: we don't care for portability.

Another good one: Oberon's definition of a static expression:
"A constant expression can be evaluated by a mere textual scan without
actually executing the program."

And the list of missing features is stunning, just some of them:
No user defined integer types (only two integer types: BYTE and INTEGER,
and they are /not/ incompatible), no enumeration types, no fixed points,
arrays indexed from 0, no variant records, no exceptions, no tasking, no
generics, no representation clauses, structural equivalence for array
parameters, no user defined operators, no overloading, no overriding, etc...

Looks more like a slightly improved Pascal appropriate for teaching than
an industrial language.

In short: if you miss most important features, and have only weak
definitions for the rest, it is easy to have a small reference manual!
-- 
J-P. Rosen
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