On Tuesday, January 15, 2002, at 06:56 PM, Hans Aberg wrote: > > I think that rather than fiddling around with operator > precedence, you need > to figure out the correct semantics in relation with the > grammar. Compare > with the grammar > http://www.jaedworks.com/hypercard/scripts/hypertalk-bnf.html
Well, they have: answer <expr> [with <factor> [or <factor> [or <factor>]]] Now, what is a factor? I quote: "<factor> is the first fully resolvable portion of an expression. Factors are covered in detail in Chapter 9 of HyperTalk 2.2: The Book." That's not a grammar, but apparently --- and testing with the reference implementation shows this --- answer "hello" with 2+2 is an error. > > Assuming that you want that the "or" of > answer ... with x_1 or ... or x_n > be treated as a ",", and when using parenthesizes around an > expression, it > should be treated as an "||", I suggest the grammar would > something like I've tried that, I got a reduce/reduce conflict. Hopefully, knowing that any operator except parenthesis being in the or list is a parse error will help. > Otherwise, I think this is a sign of poor language design. If you later > want to design your own scripting language, then you should avoid the > confusion that will inevitably arise by the "or"'s having different > semantic meaning. The language wasn't designed with the implementor in mind. I'm pretty sure it hates being implemented. Consider some other wonderful expressions: field "name" gets contents of a field card "name" refers to card by name card field "name" gets contents of a field on card layer card (field "name") refers to card by name Yep, another beautiful conflict. _______________________________________________ Freecard-general mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freecard-general
