[Haskell-cafe] Ralf Laemmel's riddle on surviving without the monad transformation library

Hi, Can someone provide me the solution to the following riddle that Ralf asked in his lecture at http://channel9.msdn.com/Shows/Going+Deep/C9-Lectures-Dr-Ralf-Lmmel-Advanced-Functional-Programming-Evolution-of-an-Interpreter Riddle: define a custom made monad (only involving (-) and Either

Re: [Haskell-cafe] Ralf Laemmel's riddle on surviving without the monad transformation library

I haven't watched the lecture. But what does he mean survive? Does it mean to do anything that you can do with mtl? On Mon, Nov 15, 2010 at 12:53 AM, C K Kashyap ckkash...@gmail.com wrote: Hi, Can someone provide me the solution to the following riddle that Ralf asked in his lecture at

Re: [Haskell-cafe] Ralf Laemmel's riddle on surviving without the monad transformation library

On Tue, Nov 16, 2010 at 3:58 AM, Luke Palmer lrpal...@gmail.com wrote: I haven't watched the lecture.  But what does he mean survive?  Does it mean to do anything that you can do with mtl? Yes ... to understand monad transformers better, he suggested trying to wrap a monad inside another (I am