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0 pointsburntsushi3y ago0 comments

Can you point to any compiler in the world that can see through the construction of a DFA from user input to the point that it can automatically optimize away the transition table lookup?

> The Result type is more appropriate to use for *functions that can fail on a regular basis.*

Emphasis mine. The DFA::is_match routine can never fail on any input. Yet, you want to use a 'Result' with it.

Seriously. Please please pretty please read the blog post. You are literally caught in precisely the tangled mess that I tried to untangle in the post. If my post didn't do it for you, then please consider responding to specific points you disagree with in the post.

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fatherzine3y ago

Sorry, I only meant to address with some nuance the statement "A failure with logic should nuke due to the app being in an inconsistent state". If you are confident that the specific DFA code in the blog post will not fail, more power to you! And to us, which transitively trust the code via your judgment ;)

Edit. For technical geeking around:

* The point is about redundant check elimination, not full check elimination. A decent compiler should be able to eliminate redundant checks, though perhaps the language could offer some intrinsics (was: pragmas) to make this 100% reliable.

* For DFA proofs, perhaps something like https://courses.grainger.illinois.edu/cs373/fa2013/Lectures/... could be a start. A great intern may tackle it over a summer ;)

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