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BLUF: I have a predicate which takes as arguments an instance of a signature and a set of instances of the same signature. Upon generating instances of the model, I'd like to pass instances of the signature to the predicate, but am at a loss for how to pass a set of instances, if it is even possible.

Alloy's Evaluator does not appear to be well-documented, unless I've missed it. I have Daniel Jackson's book, have done the tutuorial, and found various other resources online, but no one really seems to address how to use the Evaluator.

I've tried notation like:

myPred[instance$0,set(instance$1,instance$2)] and

myPred[instance$0,set[instance$1,instance$2]] and

myPred[instance$0,(instance$1,instance$2)] and

myPred[instance$0,[instance$1,instance$2]]

The Evaluator doesn't like any of them. Is it possible to pass a set of instances? If so, how do I do it? Thanks for the help!

JustAnotherSystemsEngineer
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1 Answers1

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So, in usual fashion for me, almost as soon as I asked the question, I realized the answer (or at least a way to do what I wanted to). I simply used the union operator "+" to pass the set.

myPred[instance$0, instance$1 + instance$2]

Sorry for the inconvenience, but maybe this will help someone else!

JustAnotherSystemsEngineer
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