[Haskell-cafe] extending Do notation

[silvio]

> f x
>   | a && (b > 1 || (c && d)) && e = ...
> 
> Now if 'c' becomes monadic you have to rewrite the whole expression in
> an entirely different (and much noisier) style.  Not just all the
> lifting, but you can't use infix operators anymore.  It really does
> feel like there are two languages (or dialects), with different idioms
> and syntax.  You can translate between them without much complicated
> effort, but it's still a manual translation.
> 

Good example, but i don't think you can have monads in a guard. Also I'd
go for the temporary variable instead of lifting.