https://calpaterson.com/bank-python.html
I just finished reading this, and I am quite stunned by how banks
managed to re-invent Mumps by another name. Even the source code is
stored in a database!
The other major takeaway is that GNU/Linux development practices (at
least, that's where I think where version control and continuous
integration started), notably absent in VistA, are very absent in
banking as well.
The author also has other articles that look very interesting.
--Sam