This example reads like a proof in a theory paper. It's a great illustration of the challenge of using FP: procedural thinking is difficult for humans, but abstract thinking is even harder. Imperative programming is constant procedural thinking, while functional programming is constant abstract thinking. This makes FP even better human-mind training than programming in general, but simultaneously means humans' inherent weakness at abstract thinking counteracts the power of programming functionally.

This paper focuses on application checkpointing. Section 2 includes an overview of checkpoint/recovery (CPR) research, comparing system-level CPR to application-level CPR.

CPR uses ** failure mitigation ** migrating a process to a different processor mid-execution ** extracting time-stepped information from a simulation post-execution ** debugging, including reverse debugging

Vannevar's humanitarian optimism carried forward through Licklider, Engelbart, and others for a generation beyond him - why has it faded from attention in today's computing world?