Embedding API

Neptune lang can be embedded in any rust application. The complete API can be browsed through docs.rs. Some key terms that must known are

Embedder Functions

Embedder Functions aka Efuncs are functions that are created by the embedder. They may be synchronous or asynchronous. The EFunc can push or pop values from the stack using the EFuncContext that is passed to it. EFuncs can be called using the ecall function in the vm module. EFuncs must return Result where both variants satisfy the ToNeptuneValue trait. The Err variant can be returned to throw an exception. ToNeptuneValue indicates a type that can be converted to a Neptune value. Asynchronous efuncs return a Future<Result<T1,T2>>. Examples for creating efuncs, implementing ToNeptuneValue can be seen in the documentation.

Resources

Resources are opaque handles to rust values. They can be freed using the close() method. They can be created and used only from efuncs using the resource() and as_resource() methods of EFuncContext.