I wrote this note to Mark Miller a few hours into this idea. Earlier today (2018 Jan 19) I drew a diamond picture on the board at FRIAM showing how to use two processors while imposing determinism. This is another partial stab.
I was in email conversation recently with someone about immutable functions. I can’t recall who.

Sisal avoides the problem. So too perhaps does Kappa.

I think that these ideas are centered on determinism.