small rotation or perspective skew
Here's what makes this insidious: the trampoline runs fine. genericClosure's C++ loop processes all 65,000 steps without complaint. The failure happens when you try to use the result. Forcing that final total unwinds the entire thunk chain as recursive C++ forceValue calls, rebuilding exactly the stack depth you thought you'd eliminated. The error is stack overflow (possible infinite recursion), not max-call-depth exceeded: this is the C++ call stack, not the Nix evaluator's depth limit. A simple integer counter where the comparison is the state (n: if n = N then ...) would survive, because the comparison forces the state at every step and call-by-need memoization prevents the chain. The trap springs when your state has components the step function doesn't touch.
，这一点在新收录的资料中也有详细论述
“The idea is to make the complete treatment within one millisecond,” says Stephan. “But of course, you have to [trust] that within this millisecond, everything works fine. There is not a chance to stop [during] this millisecond. It has to work.”
-config: Config