There are several strategies for code generation. The one used by MPS could be called no code generation strategy. In fact the suggested implementation for code generation is first to transform models in your language to models in the target language, or if you prefer first to transform AST representation of your program into AST representation of target language. Then models from a real language, for example Java, are translated to text. This means that only construct, like if-then-else, of language that one can compile or execute, like Java, have a place where one say how to translate them to text, in MPS called TextGen aspect.