Re: Localized precedence declarations

[Hans Aberg]

On 21 Jun 2009, at 22:46, Michiel Helvensteijn wrote:

> I'm designing a language with, among other things, unary and binary  
> operators.
> I use the Bison precedence declarations for operator precedence. I'm  
> also
> using the precedence declarations together with %prec to resolve  
> some other
> shift/reduce conflicts, such as the dangling else. It makes for a much
> cleaner grammar, in my opinion, than building the precedences into the
> grammar itself.

The problem has not been resolved, and the type of grammar constraint  
precedences I made are not implemented.

One way to implement it is to not resolve the operator precedences in  
the grammar, but in the actions. This is the only way in the case the  
operator precedences are set dynamically. One program that uses (or so  
I remember) this approach is Hugs <http://haskell.org/>.

  Hans