Re: language twiddling, was Infinite look ahead required by C++?

Chris F Clark wrote:


> BTW, I agree with Bob Duff in that there are other ways to be clear
> and unambiguous. However, initial keywords (especially when they are
> reserved words) are particularly simple to use and generally make
> proving that the language is LL(1) trivial. While this may not be a
> be-all-end-all property for a language to have, it is a good start
> especially for those who are still learning.
>
> For example, the resolution of the dangling else problem, by changing
> the syntax to have a closing terminator on if-statements, results in
> that section of the language being LL(1).


In my design (derived from Algol-68 at one point), an if-statement looks
like:


if s then s else s fi


(where s is any sequence of statements/expressions). I guess that might be
LL(1). But an if-statement can also look like:


( s | s | s )


In this case it doesn't know it's an if-statement until the second "|"
(because ( s | s, s | s ) is another kind of statement). Is this still
LL(1)? I wouldn't have thought so now.


--
Bartc
[I thought Algol-68 used a two-level VW grammar. -John]

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