This is a starting point for any Idris 2 package which might need some C glue code to call external libraries.
It also shows some small examples of foreign function calls:
- one pure function
- one which does some IO, via PrimIO
- one which has a callback
In order to make the FFI as easily portable across different backends as possible, it only knows how to deal with primitive types (including Ptr/AnyPtr), PrimIO, and callbacks involving primitive types.