MonadFail proposal (MFP): Moving fail out of Monad

[Henning Thielemann]

On Tue, 9 Jun 2015, David Luposchainsky wrote:

> the subject says it all. After we successfully put `=>`
> into Monad, it is time to remove something in return: `fail`.

Let me start the "+1" flood with my own +1.


> - - Stackage showed an upper bound of less than 500 breaking
>  code fragments when compiled with the new desugaring.

I found that code breakage generally is not a big problem for me. I can 
fix code and that's it. I am more concerned with writing code that can be 
compiled by several GHC versions.