Perhaps. But I think that you're also wandering away from the plot. Clinging to our contemporary way of thinking about this stuff isn't really going to help us

Perhaps. But I think that you're also wandering away from the plot. Clinging to our contemporary way of thinking about this stuff isn't really going to help us understand what he was grappling with 30, 40 years ago. It's more likely to muddy the waters. I don't see any evidence in there that Backus was looking for anything quite so lofty as the stuff you're bringing up. While it's true he wrote the paper that kicked off the whole idea behind FP, we've also got to keep in mind that, as he repeatedly mentions in the interview, he was a lifelong Fortran programmer who, in marked contrast to most fans of FP nowadays, held a lifelong affinity for Fortran. It sounds to me like encoding Von Neumann bits into the functional language so that you're there when you need them is exactly the sort of thing he was looking for. To my reading, his Turing lecture would seem to suggest the same.