[Haskell-cafe] ambiguous type variable question

[Tom Ellis]

On Wed, Oct 11, 2023 at 08:32:42AM +0000, Zoran Bošnjak wrote:
> I was able to implement instances (using the first proposed
> solution), but I am getting error on the call site (that is: on the
> 'main' function. The error says: ‘SchemaVal’ is a non-injective type
> family. I don't know how to get around it. I would appreciate if you
> have another look.

Sure, I'm happy to take another look, but ...

> -- Instances implementation...
> -- to be defined...

won't I need these instances in order to see how to make it work?