haskell - Should I avoid using Monad fail?

Question

I'm fairly new to Haskell and have been slowly getting the idea that there's something wrong with the existence of Monad fail. Real World Haskell warns against its use ("Once again, we recommend that you almost always avoid using fail!"). I just noticed today that Ross Paterson called it "a wart, not a design pattern" back in 2008 (and seemed to get quite some agreement in that thread).

While watching Dr Ralf L?mmel talk on the essence of functional programming, I started to understand a possible tension which may have led to Monad fail. In the lecture, Ralf talks about adding various monadic effects to a base monadic parser (logging, state etc). Many of the effects required changes to the base parser and sometimes the data types used. I figured that the addition of 'fail' to all monads might have been a compromise because 'fail' is so common and you want to avoid changes to the 'base' parser (or whatever) as much as possible. Of course, some kind of 'fail' makes sense for parsers but not always, say, put/get of State or ask/local of Reader.

Let me know if I could be off onto the wrong track.

Should I avoid using Monad fail? What are the alternatives to Monad fail? Are there any alternative monad libraries that do not include this "design wart"? Where can I read more about the history around this design decision?

question from:https://stackoverflow.com/questions/8163852/should-i-avoid-using-monad-fail