Invariants

I well remember watching this talk from Google I/O 2009: A Design for a Distributed Transaction Layer for Google App Engine. The general message:

Programmers should concentrate on invariants in the software.

And it was interesting to see them apply this is in a very specific case (where I happened to understand the problem and the context).

And I wondered whether programming languages and libraries could support this approach better.

This paper and talk by Bob Atkey looks like it is very relevant: From Parametricity to Conservation Laws, via Noether's Theorem (slides). Unfortunately understanding it is a bit of a way down my stack.