while (hGetBuf h buf bufzise .==. (return bufsize)) $ do crc =: updateCrc crc buf bufsize breakIf ((val crc) .==. (return 0)) `orElse` do printM (val crc) od
your solution is just to make lifted copy of each and every pure operation. so one should define 2^n operations where n is number of arguments
ah, I thought the problem at hand was breaking out of a while loop. but if you look closely, I think you'll find it to be ~2 operations, the monadic one, and possibly a pure one to be lifted. one can always lift pure arguments via return, and use the fully lifted monadic operation, as I did in the example code (you were talking about imperative programming, after all?-). if one were to go down that route, one would probably want to overload literals, such as (Num a,Monad m) => Num (m a) for fromInteger, rather than writing (return 0) everywhere, and as usual, the obligatory superclasses would get in the way and would have to be ignored, and Bool isn't overloaded, .. all the usual suspects for hampering embedded DSLs in Haskell. Claus