I've just started my first MPS project. I want to create a new language, which borrows concepts of the baselanguage. This means I have my own root elements and my own statements which uses some types and expressions of java. But I don't want to have all java types and expressions. Because types and expressions can occur in many places in my language I'm not sure where and how to constrain which of the concepts are allowed.
Has any body an advice how to do this?