Comment by StiffFreeze9

Other "biphasic"-like aspects of programming languages and code:

- Documentation generated from inline code comments (Knuth's literate programming)

- Test code

We could expand to

- security (beyond perl taint)

- O(n) runtime and memory analysis

- parallelism or clustering

- latency budgets

And for those academically inclined, formal language semantics like https://en.wikipedia.org/wiki/Denotational_semantics versus operational and others..