In the last 7 days I implemented a complete XPath 1.0 parser & evaluation system from scratch in C++20. Right now I'm adding support for XPath 2.0.

Codex in the cloud has been leveraged to do 95% of the work and Claude 5%. We've output 10.5K LoC and 774 individual tests to ensure compliance to the spec.

Lately I've been feeling like we're living firmly in the future. This would easily be an 8+ month project on my own not including the tests, yet we're now on track for completion in 10 days. A min. 25x speed increase is a crazy level of productivity for me and it's hard to believe I'm still seeing articles claiming that AI coding isn't productive.

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Havoc 3 days ago | parent [-]

I'd imagine part of it is that there are xpath parsers on github already, so it's not entirely greenfield for the models.

	▲	paul_manias 3 days ago \| parent [-]
		Partially, but I think it's moreso the W3C spec being so thorough and the wealth of samples online. I found that during code review both Codex and Claude would refer back to the specs for certainty on expected outcomes. Their understanding of how to deal with unusual edge cases was also impressive, so it seems they have a lot of baked in knowledge & training of how XPath works and they draw from that.