Monadification of functional programs

The structure of monadic functional programs allows the integration of many different features by just changing the definition of the monad and not the rest of the program, which is a desirable feature from a software engineering and software maintenance point of view. We describe an algorithm for the automatic transformation of a group of functions into such a monadic form. We identify two correctness criteria and argue that the proposed transformation is at least correct in the sense that transformed programs yield the same results as the original programs modulo monad constructors.