[Question] How to allow arbitrary user defined values

I'm creating a DSL using HCL, and bumping up against the ability to let users define a (mostly) arbitrary attribute.

Given an example HCL config like so:

example "resource_putter" {
  inputs = {
    foo = "foostring"
    bar = true
    buzz = vars.some_complex_value
  }
}

The values of the keys under inputs can effectively be anything. I can happily parse this into cty.Values, but I've not a found a non-janky way of getting that into an interface{} as I would with unknown json input, for example.

The exact syntax above is one example. I can flex within reason if there's some more supported way of handling this built-in. I could have inputs as a block, or change the structure in other ways if it makes it more feasible.

My main needs are that users can define a structure without having to template json strings (will be error prone and bad user experience), they should have access to the expression context and the top level keys will always be strings.

I've been bashing my head against this for over a day now and I'm basically out of ideas beyond recursively parsing the structure myself. That will work, but it seems others must have faced and solved this ahead of me.

Start by reviewing the HCL expression and cty.Value handling described in the issue, especially how arbitrary values could preserve access to the expression context. Compare the requested inputs attribute with the suggested block structure and determine whether either has a supported representation in Go. Done means identifying and documenting a concrete supported approach, or confirming that custom recursive parsing is required.