How should we handle transformations?

[boyeln]

Sometimes you have types that needs transformations. The simplest example is Date (or data time). This can be solved today through custom scalars (setting it to string). And then transformed/parsed in userland to the proper Date object/type.

Can we do better or is this the optimal solution? If it's the best solution, is there a golden path for people wanting to do custom transformation/parsing that's easy to integrate into the type system?