Process

E.Process is what the running process knows about its environment: cwd(), home() and argv() today, with environment variables to follow. The directories return an E.Path, argv() a tuple[str, ...] without the program name. It is an explicit requirement like the FileSystem, so a CLI reads its starting directory through it and a test pins that directory with E.Process.Test(current_directory=..., home_directory=..., arguments=...) instead of depending on where pytest happens to run.

def from_cwd[A, Err: E.EffectonError, R](
    program: Callable[[E.Path], E.Effect[A, Err, R]],
) -> E.Effect[A, Err, R | E.Process.Protocol]:
    return E.require(E.Process.Protocol).flat_map(lambda p: p.cwd()).flat_map(program)
 
 
E.run_main(
    from_cwd(status)
    .provide(E.Process.Protocol)(E.Process.Live())
    .provide(E.FileSystem.Protocol)(E.FileSystem.AsyncLive())
)