[Haskell-cafe] Question about typeclass & constraints

[Tom Ellis]

On Tue, Apr 08, 2014 at 09:25:17AM +0200, jean-christophe mincke wrote:
> instance (PP m) => PP (B m) where
>     create a =  let _ = fb a
>                 in B (create a)

Your use of 'fb' here is baffling.  Am I right in thinking you have tried to
simplify your problem for clarity?  If so I think you have simplified too
far!

Could you give an example where the use of 'fb' actually matters?

Tom