Support Composite Types (struct) as event parameters

[joshuahannan]

Issue To Be Solved

It would be useful to be able to use a composite type as an event parameter so contracts can communicate complex information with the outside world without having to awkwardly split up the data.

Suggest A Solution

• Support for any struct as a event parameter
• Support for understanding and parsing the struct in other languages like Go.
• Do not support resources

Context

This is blocking our ability to efficiently emit important events in the Flow Epoch Smart Contracts. We have a workaround, but would prefer to emit structs in our events.

Definition of Done

• Sema: Allow structs as event parameters
• Tests: Sema, Interpreter
• Documentation

[turbolent]

This should be easy to support for structs, as they are copied.

The change itself would entail adding a case in sema.IsValidEventParameterType

[turbolent]

@joshuahannan This is a good first issue, would anyone from the Reliability Pod working on the contracts be willing to pick this up? It should be fairly small and I'd be happy to assist

[joshuahannan]

I could do it if you can help me out!

[turbolent]

Definitely! Let me know when you'd have time and we could pair up if you want