Function compile_polydat_with 

pub fn compile_polydat_with(
    source: &str,
    engine: Engine,
) -> Result<Box<dyn Kernel>, KernelError>

Compile source for engine: the interpreter, the closure tier, the hybrid kernel, or pure native code. Every engine accepts every program the interpreter accepts, or refuses it with a reason (crate::KernelError::Refused); a host drives the result through crate::Kernel without knowing which engine it holds. The compile_polydat_kernel* and compile_polydat_checked entry points are this on Engine::default(); compile_polydat, compile_polydat_with_options, and the deprecated forms build the interpreter’s kernel.