[Haskell-cafe] Design of a DSL in Haskell

This is probably a very basic question. I am working on a DSL that eventuyally would allow me to say: import language.cwmwl main = runCWMWL $ do eval ("isFib::", 1000, ?BOOL) I have just started to work on the interpreter-function runCWMWL and I wonder whether it is possible to escape to real Haskell somehow (and how?) either inside ot outside the do-block. I thought of providing a defautl-wrapper for some required prelude functions (such as print) inside my interpreter but I wonder if there are more elegant ways to co-loacate a DSL and Haskell without falling back to being a normal library only. --Joerg