Re: Eliminating conflicts of parenthesized subexpressions

[Hans Aberg]

At 10:59 +0200 2004/09/13, Akim Demaille wrote:
> >> So a simple form of type checking might also do the trick here;
> >> however, type checking is better not done in the grammar, I think.
>
> > I looked a bit in Aho, Sethi & Ullman, "Compilers..." (the Dragon
> > book), p.  351 ff., and they do it in the actions.
>
>Choose your "better" and then the discussion will be meaningful.  If
>you're not interested in performances, Vincent is definitely right.

I find it hard to parse this one :-): If one should be able to catch
semantic type errors, then the actions must contain some code indicating
how those types should be computed. Then that must be checked at sometime.
What is the performance issue you have in your mind here?

>And let's face it at least once: The Dragon Book is obsolete (another
>edition is expected though).

People say that, but it probably depends on what one wants to do. It
probably only wants to provide the basics, anyhow. And I figure computer
language constructors and implementers do better to not stare to deeply in
books, but use their own mind, as well hanging out in suitable newsgroups
and mailing lists.

I recently read a book that for some reason was on my bookshelf:
  David A. Watt, "Programming Language Concepts and Paradigms".
The interesting thing with this book, is even though it is also obsolete,
being written in 1989 and oblivious about the developments in the 1990'ies,
it has some insightful remarks about the limitations of the computer
languages of the day, which are still valid today in newer computer
languages. So, one can get some information out of also older books.

  Hans Aberg