Simple yes, but consistent too should be a factor.

Most questions we have to the user mailing list involve people writing DRL not using tooling.

So DRL, IMO, has to be seen as the "tool" to author rules. Drop the proposed colon altogether or make it's use consistent.

On 20 April 2011 17:42, Mark Proctor <mproctor@codehaus.org> wrote:
My personally opinion is to keep the language simple and instead have the tooling inject what ever is necessary as a visulation. Be it different colouring, hover over or graphic symbol. It keeps the language simple and actually achieve the desired result better.

Mark

On 20/04/2011 14:00, Leonardo Gomes wrote:
+1 for Michael's suggestion.

It's a bit more verbose, but makes things clear.

The semicolon here:
?editableThings(food : ?, loc;)

Is a typo, right? You actually meant:

?editableThings(food : ?, loc);

- Leo.



On Wed, Apr 20, 2011 at 11:59 AM, Michael Anstis <michael.anstis@gmail.com> wrote:
Hmmmmm....

Personally, I don't like the use of ":" i isolation as it's what we currently use to bind variables and I feel "cheese:" as an output definition could just make people question whether they've missed something. Perhaps "cheese : ?" would be a viable alternative. This would be in keeping with (a) current variable declaration, (b) the use of "?" to identify a call to a query. Geoffrey's examples would then become:-


rule outputinput
when
    Here( loc : location)
    ?editableThings(food : ?, loc;)
then
    System.out.println("Food " + food + " at location " + loc);

    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
end

rule outputOutput
when
    ?editableThings(food : ?, loc : ?;)
then
    System.out.println("Food " + food + " at location " + loc);

    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
    // Food chocolate at location living room
    // Food chips at location living room
end
rule typo
when
    Here( looc : location)
    ?editableThings(food : ?, loc : ?;)
then
    System.out.println("Food " + food + " at location " + loc);

    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
    // Food chocolate at location living room
    // Food chips at location living room
    // looc is just an unused bound variable
end


On 20 April 2011 10:16, Geoffrey De Smet <ge0ffrey.spam@gmail.com> wrote:
Mark and I were discussing backwards chaining
  http://blog.athico.com/2011/04/backward-chaining-emerges-in-drools.html
on IRC and we 'd like your opinion on a design issue.

The example
========

Let's say you have this data:
  Location("crackers", "kitchen")
  Location("apple", "kitchen")
  Location("chocolate", "living room")
  Location("chips", "living room")

Let's say you have this code:

query editableThings( String thing, String location )
    Location(thing, location)
end

And then these 3 rules:

rule outputinput
when
    Here( loc : location)
    ?editableThings(food, loc;)
then
    System.out.println("Food " + f + " at location " + loc);
    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
end

rule outputOutput
when
    ?editableThings(food, loc;)
then
    System.out.println("Food " + f + " at location " + loc);
    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
    // Food chocolate at location living room
    // Food chips at location living room
end
rule typo
when
    Here( looc : location)
    ?editableThings(food, loc;)
then
    System.out.println("Food " + f + " at location " + loc);
    // Output:
    // Food crackers at location kitchen
    // Food apple at location kitchen
    // Food chocolate at location living room
    // Food chips at location living room
end


The discussion
=========

Both rules have the same statement:
  ?editableThings(food, loc;)

In the outputInput rule, "loc" is an input variable.
In the outputOutput rule, "loc" is an output variable.

I am wondering if we don't need a visual demarcation that a variable is an output variable,
to make it stand out of an input variable?

Proposition 1: Suffix output variables with ":"

rule outputinput
when
    Here( loc : location)
    ?editableThings(food:, loc;)
then ... end
rule outputOutput
when
    ?editableThings(food:, loc:;)
then ... end

rule typo
when
    Here( looc : location)
    ?editableThings(food:, loc;) // compiler error because input variable loc is not declared
then ... end


--
With kind regards,
Geoffrey De Smet

_______________________________________________
rules-dev mailing list
rules-dev@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-dev



_______________________________________________
rules-dev mailing list
rules-dev@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-dev



_______________________________________________
rules-dev mailing list
rules-dev@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-dev


_______________________________________________
rules-dev mailing list
rules-dev@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-dev