[rules-users] Partial Unification / Derivation of Facts?

[JohnnyCaimbridge]

Let me start from scratch as I'm realizing how difficult it is to understand
my issue.

There is a Fact "A" with some rules use as conditions.  "A" can be derived
in several different but mutually exclusive ways.  For the most part, the
rules which define each of these derivations depend on states/conditions
which the rules matching on "A" are largely agnostic of.

rule "rule deriving A"
when
   //some conditions
then
   insert( new A(/*some values*/) );
end

rule "another rule driving A"
when
  //some other conditions
then
  insert( new A(/*some other values*/) );
end

// many other rules deriving A


However, there are also other "parameters"/"values" needed for the
computation of the many derivations of "A" (they need to be present in the
RHSs of rules deriving "A").  The combination of these values are
context-dependent to each matching of "A" /every time/.  That is, each
matching of "A" has a unique set of values binded to a particular set of
parameters expected by rules deriving "A").  Rules deriving "A" need not and
should not match on these parameters because they are different for every
matching of "A"; the derivations should (ideally) take on whatever values
are specified in the matching.

rule "rule matching on A"
when
  $a : A() // needs to somehow convey to the derivation of A() that it
should use a set of values unique to this matching in its derivation
then
  // use $a
end

rule "another rule matching on A"
when
  $a : A() // needs to somehow convey to the derivation of A() that it
should use a set of values unique to this matching in its derivation
then
  // use $a
end

I cannot leave it up to the rules deriving "A" to handle every single case
of different values for these parameters--there would be thousands of
different combinations of derivations of "A" and nobody would understand the
code.

The rules deriving "A" cannot match on general "Parameter" objects because
the values in the Parameter objects are unique for each matching of "A". 
This would mean that each rule matching "A" would need a counterpart rule
which asserts the parameters/values needed by the rules deriving "A".  I
mean, I suppose this /is/ a solution, but it's obviously difficult to
understand design.

I guess what I'm looking for is something inbetween a function (with
explicitly binded parameters) and a derivation that is rule based--to be
able to say "derive this kind of object in any way that you can, but use
these particular values in its derivation".  Perhaps this is not possible.

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