Currently, only a Rust SDK has been produced and can be used within the Holium protocol.
The statically typed languages that we look forward to the most after it are AssemblyScript and Golang.
As for how the Rust SDK API behaves, it currently ingests data as whole without any optimization. Ideally, that behavior would be changed so that data are dynamically fetched during the execution of a transformation.
If those tasks interest you or if you have any query about them please feel free to reach us on any of our contact channel.