FWIW if you're not using algebra to write your software you're not quite doing FP just yet. Doing math on software to make new software is the overlooked part

FWIW if you're not using algebra to write your software you're not quite doing FP just yet. Doing math on software to make new software is the overlooked part of FP in my opinion. You hear about "first-class functions" and "referential transparency" a lot but not as much about "equational reasoning".