The more I study functional programming the more I see a mapping between structures (reduce/fold,...) and assembly. Assembly requires you to be very very careful, but if you're used to that you can encode these patterns in short ways. But it's a lost art nowadays.
Old cpus had a simpler arch (68000 ancestor or something like that), often with two registers A,B serving as accumulator,next pair for reduce/fold like processes. To me it's clearly a reflection of mathematical structures, which are also the root of FP.
With time register sets grew, ISA grew, this got muddied by usage.
