Are heating and cooling rules part of the syntax?

In the IMP tutorials, we can see the keywords heat and cool being used. I haven’t been able to get K to compile rules in this form, however. Particularly, the example uses [] to denote the holes in the evaluation context. Are these labels present in K?

For instance:

rule T:Term + T2:Term => T ~> [] + T2 [heat]

Fails to compile, highlighting the first [. In the tutorial we see something similar given as an example.

[dwightguth]

It’s going to branch based on which rules apply, so it should only need to do two branches.

The transition attribute tells the java backend that this rule is considered a transition in the state graph of the semantics and thus it should try to apply every single rule and generate the complete list of successor states instead of simply choosing the first rule that applies as an optimization. Ultimately we decided that this makes things confusing for users and thus removed the need to do this in the haskell backend, but the haskell backend is still under active development and cannot run every definition that the java backend supports yet. I would advise you to use the java backend for the time being unless you want to try the haskell backend and it works for you out of the box with no errors or bugs. Hence my suggestion to use the attribute on critical pairs in the semantics.

[dwightguth]

The java and haskell backends definitely contain built-in symbolic execution. If you write rules like:

rule if true then A else B => A [transition]
rule if false then A else B => B [transition]

and you krun --search the term if ?A then 1 else 0, it should generate two output configurations, 1 and 0. It doesn’t generate a compatible value for ?A, it actually stores it in the term being rewritten as a symbolic value and unifies it with the rules being executed while tracking the symbolic constraints.

Does that answer your question?