Printing the value of the configuration - kframework

Question

While modifying the toy language SIMPLE from the tutorial, I thought it would be helpful to have a statement that would just print the current configuration so that I could see the internal state of the program as it ran. To that end I added to Stmta printConfig command. In the semantics then I figured all I had to do was rewrite this to a call to print taking the body of the T cell so I added
rule <k> printConfig; => print(cfg); </k>
<T> cfg </T>
The kompiler throws an error saying that there is an unexpected end parenthesis, specifically the one for print(cfg). I'd encountered a similar issue previously and in that case the error turned out to be due to the typing of the components of the two statements I had. I'm wondering then if there is a way to "cast" the value in the T cell as an Exp so I can print it.
If there is a better way I can debug my semantics that does not involve this I am very open to that as well. Thank you!

Answer 1

Well one issue I can see is that you have <k> and <T> cells next to each other in your rule, but they don't have a sibling relationship in the initial configuration.
The SIMPLE configuration looks like this, where the <k> cell is a grandchild of the <T> cell:
configuration <T color="red">
<threads color="orange">
<thread multiplicity="*" color="yellow">
<k color="green"> $PGM:Stmts ~> execute </k>
<control color="cyan">
<fstack color="blue"> .List </fstack>
<xstack color="purple"> .List </xstack>
</control>
<env color="violet"> .Map </env>
<holds color="black"> .Map </holds>
<id color="pink"> 0 </id>
</thread>
</threads>
<genv color="pink"> .Map </genv>
<store color="white"> .Map </store>
<busy color="cyan"> .Set </busy>
<terminated color="red"> .Set </terminated>
<input color="magenta" stream="stdin"> .List </input>
<output color="brown" stream="stdout"> .List </output>
<nextLoc color="gray"> 0 </nextLoc>
</T>
So if you want to write your rule, you at least have to do this:
syntax Stmt ::= "printConfig" ";"
rule <T> ... <k> printConfig; => print(CFG); ... </k> ... </T> #as CFG
Notice that I made three changes here, (1) I used capital letters for the variable CFG (which is conventional in K), (2) I added the ... to the end of the <k> cell, which allows you to use printConfig; anywhere instead of just at the end of a program, and (3) I used an _#as_ pattern to match both the super-term <T> ... </T> as well as the sub-term <k> ... </k> at the same time, giving the name CFG to the super-term.
_#as_ patterns are documented in the Pending Documentation.
Hope that helps!