Fundamentally this book is about the application of abstract algebra to the analysis of accounting systems.
Add in APL or J (or Haskell if you must) by way of "Algebra: An Algorithmic Treatment" (http://www.amazon.com/Algebra-algorithmic-treatment-Kenneth-...), and you build a quite rigorous proof-based accounting system.
"This book describes the construction of algebraic models which represent the operations of the double entry accounting system. It gives a novel, comprehensive, proof based treatment of the topic, using such concepts from abstract algebra as automata, digraphs, monoids and quotient structures."
Think of it as a primer for building yourself an exceedingly awesome and utterly-unnecessary Haskell-based QuickBooks.
Source: https://github.com/kdeldycke/awesome-billing#finance