Decoding really "flexible" JSON schema?

[joelq]

@jacob

In my experience, when you’re thinking about problems like this it’s much more fruitful to work backwards from the Elm type you’d like and derive the decoder from that than it is to try to work forwards from the JSON you want to decode

Strongly agree with @jacob . It’s much easier to figure out decoders once you’ve defined the problem as “I have this JSON and I want to decode it into this type”

In this situation, you’ll have to resolve a lot of the ambiguity just to design types that capture the information you need. Is everything going to be stored in some super-generic tree or graph structure? Perhaps you want to force everything into one of n predefined record shapes? Something else altogether?

designing these types is the hardest part. Once you have these it makes figuring the decoders much more straightforward. Generally some combination of andThen and oneOf (with a bit of keyValuePairs thrown in if you need the names of keys)