i agree, this overlap is a problem. and i agree that there's a not-obviously-wrong argument to be made that ignoring SPMs is the wrong approach. to this end, someone pointed me to rubinius' wiki yesterday, which had a nice breakdown of the PM hierarchy: https://github.com/rubinius/mkrb/blob/master/README.md#the-m...

OTOH: part of the reason that i included the notion of "compiler, phase zero" is because i think that's one thing that, scope-wise, differentiates SPMs from PDMs. an SPM's output is executables. i think this difference is significant. maybe i'm wrong.

(If anything, I think there's more overlap between an SPM and an LPM).