[Haskell-cafe] Avoiding code-duplication for what is roughly fmap

[Tom Ellis]

On Thu, Oct 03, 2019 at 04:55:24PM -0400, Sebastiaan Joosten wrote:
> I'm writing a lot of code that looks like this:
> instance WhiteSpaced ClassItem where
>   removeWS (Method a b c) = Method (removeWS a) (removeWS b) (removeWS c)
>   removeWS (Declaration b) = Declaration (removeWS b)

I'll give you an example using product-profunctors, but could you provide
the class and data type definitions?  I'd like the example to actually
reflect the reality of the situation you are dealing with.