Access variable in log:collectAllIn pattern in rule

[lolgab]

I'm trying out notation3 with eyereasoner and I have a problem I don't know how to solve.
Given data for "transactions" I want to calculate the total amount of a ?thing.
I managed to calculate the total using log:collectAllIn to first create a list of integers and then pass this list to ?list math:sum ?result to sum its values.
My problem is to keep the reference to a node that I find in the pattern passed as the second value of the list that is used together with log:collectAllIn.
In the following example, ?thing in the result is not the same as ?thing in the pattern.

@prefix log: <http://www.w3.org/2000/10/swap/log#> . 
@prefix math: <http://www.w3.org/2000/10/swap/math#> .
@prefix : <http://example.org/> .

{
  (
    ?amount
    {
      ?a
        :destination ?thing ;
        :amount ?amount .
    }
    ?amounts
  ) log:collectAllIn _:t .
  ?amounts math:sum ?amountsTotal .
} => {
  ?thing :total ?amountsTotal .
} .

How would you solve such problem with n3?

Thank you,
Lorenzo

[josd]

You have to bind ?thing outside log:collectAllIn for instance as

{
  ?x :destination ?thing. 
  (
    ?amount
    {
      ?a
        :destination ?thing ;
        :amount ?amount .
    }
    ?amounts
  ) log:collectAllIn _:t .
  ?amounts math:sum ?amountsTotal .
} => {
  ?thing :total ?amountsTotal .
} .

and that should give :total triples for all different ?thing's

[lolgab]

Thank you very much for your help! Binding the ?thing variable outside works indeed! It's not very clear to me why it does but I'll keep it in mind.
By the way, n3 and the eye reasoner are amazing! I'm amazed by how elegantly you can solve problems!

[lolgab]

I just realized that you can bind the ?thing variable in whatever way you want, so, since my rule applies to nodes of a specific type I can just bind it with:

?thing a :ThingType

Which makes the rule more readable.