Writing a subtype function

Hi all, I apologize if this isn’t the right place for this sort of question, but I’m at a loss as to how to use TcUnify.tcSubType. My goal is to write a function of type Type -> Type -> Ghc Bool which checks whether the first argument is a subtype of the second. I assume this is possible to do using TcUnify.tcSubType and runTcInteractive, but it’s not clear to me how. Any pointers here would be greatly appreciated.