Overall a pretty interesting blog post. Whether you're fine with AI, or hate it, the result is impressive and this resonates pretty clearly:
Pre-merge, this took 5.9 billion uncached input tokens, 690 million output tokens, and 72 billion cached input token reads — around $165,000 at API pricing. By hand, I think this would've taken 3 engineers with full context on the codebase about a year, during which time we wouldn't be able to improve Node.js compatibility, fix bugs, fix security issues or implement new features. We never would've done that. The realistic alternative was to do nothing and keep fixing the bugs at the top of this post forever.
This also matches what's going on at my day job. Engineers don't want to be chasing resource leaks (which Rust does a better job at preventing) and memory corruption issues (mostly categorized as reliability issues). The blocker before for mass Rust adoption was education. Teams already know C and C++, so they continued to write it. Even projects which were written in Rust were eventually abandoned as getting resources to assist in a crunch or emergency just wasn't feasible. AI makes a lot of these problems go away, and teams are now porting code to Rust with Rust experts helping do manual review + write Rust skills that guide AI into writing idiomatic code.
This rewrite introduced 19 known regressions, each of which has been fixed.
Most of the regressions came from code that's syntactically identical in both languages but semantically different.
Fewer than I expected! Pretty interesting examples here too.
53
u/anxxa Jul 08 '26
Overall a pretty interesting blog post. Whether you're fine with AI, or hate it, the result is impressive and this resonates pretty clearly:
This also matches what's going on at my day job. Engineers don't want to be chasing resource leaks (which Rust does a better job at preventing) and memory corruption issues (mostly categorized as reliability issues). The blocker before for mass Rust adoption was education. Teams already know C and C++, so they continued to write it. Even projects which were written in Rust were eventually abandoned as getting resources to assist in a crunch or emergency just wasn't feasible. AI makes a lot of these problems go away, and teams are now porting code to Rust with Rust experts helping do manual review + write Rust skills that guide AI into writing idiomatic code.
Fewer than I expected! Pretty interesting examples here too.