Omniscient Printf Debugging In Pernosco

Source: Eyes Above The Waves Topic: Querying a recorded execution instead of repeatedly rerunning it.

Core idea

Pernosco treats execution history as something that can be searched and queried after the fact rather than merely stepped through linearly.

Key claims

• A recorded execution can answer questions that normally require adding print statements and rerunning.
• The interesting interaction is query-based and retrospective, not just forward stepping.
• The debugger becomes closer to an analysis database over execution history.

Harness takeaway

Validation traces in a harness should be queryable artifacts. Operators should be able to ask when something first failed, where a value changed, or which branch introduced a regression without rebuilding the whole world every time.