Re: How to change default outcome of shift/reduce conflict?

[Anthony DeRobertis]

On Tuesday, January 15, 2002, at 07:38 PM, Hans Aberg wrote:
> Here, the action $1 | $3 would check the types of $1 and $3, 
> and if they
> are combinable into a Boolean value it would do so; otherwise, it would
> combine them into a list object. (Think on for example C++ operator
> function name overloading based on argument type.)

This language is very weakly typed. So I don't know at parse 
time the type of a variable, or for that matter that it is a 
variable... could just be an unquoted string.

also:

        answer "hello" with true or false

has two buttons. So I couldn't do that even if I had type information.

> > From the theoretical point of view, we merely give up trying 
> > to capture the
> language (specifically, the distinction between the two 
> different "or"'s)
> using a context free grammar alone: If we would want the 
> grammar to capture
> this construction, it would lead to an attribute grammar or something.

I believe HyperCard --- the reference implementation --- uses a 
hand-written recursive descent parser. Or at least I've heard 
rumors to the effect. So I get to hold out some hope.