[rules-dev] Drools syntax diagrams - redrawn

[Mark Proctor]

  On 22/09/2010 17:20, Wolfgang Laun wrote:
> See my remarks inline.
>
> On 22 September 2010 17:03, Mark Proctor <mproctor at codehaus.org 
> <mailto:mproctor at codehaus.org>> wrote:
>
>      So things that are doing are:
>
>     Single binding on 'or'
>     $binding : ( Pattern() || Pattern() )
>
>     We are thinking of only allowing 'or' between patterns and not
>     allowing users to mix and match 'or' and '||'.  Inside of patterns
>     '||' is the only connective allowed and will remain so.
>
>
> OK, a clear distinction avoids confusion.
>
>
>     We will also probably make a choice and only allow infix 'or' and
>     'and', at the moment users can chose infix or prefix. Personally I
>     find prefix quite attractive as it works sort of like a "choice":
>     (or Person(  ... )
>           Person( ... )
>           Person( ...) )
>
>     But I think most peopel are more comfortable with infix:
>     (Person(  ... ) or
>       Person( ... ) or
>       Person( ...) )
>
> (name ... ) is neither function style nor infix, so removing yet 
> another way of writing expressions is OK. Let's infix.
The prefix way, shown above was following what jess and clips did. Our 
initial mindset was based on those two engines, in trying to make a more 
comfortable environment for them to transition too. We are now in a more 
comfortable position and able to do what is right for our existing 
community and worry less about appealing to other communities.

Mark
>
>     return value, eval, literal constraint, variable constraint are
>     going. These are left overs of a Clips based grammar. So instead
>     we'll have a generic "expr" class that follow more common modern
>     ASTs for expression engines, like say MVEL.
>
>  OK!
>
>
>     Davide has also requested that we make $ prefix mandatory for LHS
>     bindings as that is deterministic and again makes the grammar cleaner.
>
> I don't understand why it should be "cleaner". After all, a '$' could 
> even result from a Java identifier although this is discouraged, 
> according to the Language Spec.
>
>     I personally like it being optional and it's still open to debate.
>     But I recognise the need to have better maintained grammar, that
>     is more consistent and regular with easy to main documentation.
>
> There's one thing that would help: Make the NT identifiers in the 
> grammar "user friendly". I had to replace all of them with NT 
> identifiers that are self-explanatory. Also, whenever possible, stick 
> to the terms in the Java grammar if it's the same thing, e.g. 
> "QualifiedIdentifier", "Block", "Expression", etc.
>
> -W
>
>     Mark
>
>>
>>     Some rules can be omitted if they coincide with Java's own rules;
>>     just add an explanation.
>>
>>     -W
>>
>>
>>     On 22 September 2010 14:56, Anstis, Michael (M.)
>>     <manstis1 at ford.com <mailto:manstis1 at ford.com>> wrote:
>>
>>         What was the service and was it the ANTLR grammar you uploaded to
>>         generate the images?
>>
>>         Thanks,
>>
>>         Mike
>>
>>         -----Original Message-----
>>         From: rules-dev-bounces at lists.jboss.org
>>         <mailto:rules-dev-bounces at lists.jboss.org>
>>         [mailto:rules-dev-bounces at lists.jboss.org
>>         <mailto:rules-dev-bounces at lists.jboss.org>] On Behalf Of
>>         Wolfgang Laun
>>         Sent: 22 September 2010 13:38
>>         To: Rules Dev List
>>         Subject: [rules-dev] Drools syntax diagrams - redrawn
>>
>>         I've found this online service and stuffed the Drools grammar
>>         into it.
>>
>>         You may see the results while they are still there:
>>         http://www-cgi.uni-regensburg.de/~brf09510/syntax.tmp/x45371x0x0x.ebnf.h
>>         tml
>>         <http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebnf.h%0Atml>
>>         <http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebn
>>         f.html
>>         <http://www-cgi.uni-regensburg.de/%7Ebrf09510/syntax.tmp/x45371x0x0x.ebn%0Af.html>>
>>
>>         -W
>>
>>
>>
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>>
>>
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>
>
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