Re: newbie can't get exceptions to work!

[Laurent Guerby <guerby@acm.org>]

Brian Rogoff <bpr@shell5.ba.best.com> writes:
> On 9 Apr 2001, Laurent Guerby wrote:
> > broken case statements,
> 
> Broken semantically. Using the name switch wouldn't make a difference. 
> Besides, I much prefer ML or Haskell pattern matching to Ada's case 
> statement. More readable, more powerful, terser, better. 

Well, that's no longer syntax ;-). The horror I was refering too was
the optional break as you might have guessed. Also I find the
mandatory enumerate all rule in alternatives of Ada is quite useful.

I agree that pattern matching is something very nice to have anyway.

> > named and order free arguments and agregates, 
> 
> Would be nice. There is some discussion about adding this to Ocaml now
> too. You can use labelled params, but commuting arguments are still up in
> the air. 

I must admit I don't understand why every language doesn't have this
feature, especially all those conceived after Ada like OCaml. I
suspect we should mandate Ada history and design rationale lectures to
all language creators, a lot of engineering went into Ada, and we've
had a lot of time to judge the work done.

My favourite citation here is from Steve McConnell in "code Complete":

   Finally, the goto was incorporated into the Ada language, the
   most carefully engineered programming language in history.

> > and operator character choice, 
> 
> True, but I must say that the += and friends are nice. Of course an Ada
> version would be +:= and still nice. 

That's a possibility. Another is to have a way to generate tersely
procedural versions of operators, may be (ok ugly ;-)

procedure Inc is procedural "+";
-- Inc (X : in out T; Y : in T) is begin X := X + Y; end Inc;

Not really functional BTW ;-).

> And while I don't like the syntax, the ? : of C is also nice, but,
> as you know, I'm a functional kind of guy now.

This is not just syntax here, Ada doesn't have a way to do the same as
C here because of strictness in argument evaluation. I recently
designed a small language with an Ada-style syntax and I added "if"
expressions :

X : constant T := if C1  then V1 elsif C2 then V2 else V3;

This is something I think people miss in Ada, may be someone should
wrote an extension proposal ;-).

> > And I would absolute religious belief in keeping those
> > historical mistakes around (see Java).
> 
> I can't parse that. Let me guess, "And I would add, an absolute ..."?

You have a powerful syntax recovery parser in your brain ;-).

> > If {} vs begin/end is issue for a new language, allow both and end of
> > the story.
> 
> That would be a mistake. Personally, I can go either way, begin-end or {}. 
> I'm just annoyed at the bizarre thinking that puts one of these as greatly 
> superior to the other. I really find () to be a bummer about Ada syntax
> and I don't agree that wordier is always better. 

As other people pointed out, another advantage of end syntax is the
"end thing" which is quite nice. I think that if you allow declarations
to float around, the argument about terseness of {} becomes moot, eg:

procedure P is
   variable X : T := Initial;
   while Cond (X) loop  
      constant Tmp : T := G (X);
      if Cond (Tmp) then
         Do_Thing (Tmp, X);
      end if;
      Next (X);
   end loop;
end P;

would not gain much from {}.

And I of course forgot the mandatory () for function calls without
args silliness ;-).

> > PS: also, on a french keyboard, {} [] are a major pain to type ;-).
> 
> Hey man, get an American keyboard!

No, I just program in Ada at home and work ;-) ;-).

-- 
Laurent Guerby <guerby@acm.org>