Coq
Hacker ApprovedRanked 3 of 8 proof assistants by recommenders
Free theorem prover people use to write machine-checked proofs, praised for rigor and strong tactics. Caveat: proofs are hard to read and maintain, and adoption is limited.
Free theorem prover people use to write machine-checked proofs, praised for rigor and strong tactics. Caveat: proofs are hard to read and maintain, and adoption is limited.
32 people gave an opinion
- recommend it
- 24
- criticize it
- 8
- approval share
- 75%
Recommended in 9 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: not recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: not recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: not recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 24 people recommend itNeeds 10 or more, met.
- 3 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 9 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Forces careful thinking and strict checking
“since the type system is comprehensive enough to force you to actually think about what you really want”
Comment from 9 Jan 2026 in “Why AI is pushing developers toward typed languages” “The proof checker is much more ruthless than the rust compiler.”
Comment from 27 Jan 2026 in “Any application that can be written in a system language, eventually will be” “The Coq language's rigor really helps with something like this.”
Comment from 27 Nov 2025 in “Coq: The World's Best Macro Assembler? (2013) [pdf]” - Comment from 12 Dec 2025 in “Programmers and software developers lost the plot on naming their tools”
Verifying AI-written code with proofs
“ask your agent to verify critical protocols with formal proof in TLA+/lean/coq”
Comment from 12 May 2026 in “If AI Writes Your Code, Why Use Python?” “They are cleaner mathematically, which means AI has a better chance with them.”
Comment from 12 May 2026 in “If AI Writes Your Code, Why Use Python?” “Prove your code directly in Lean or Coq or leave it.”
Comment from 17 Sep 2026 in “Bend – a language that blocks AI mistakes via proof and runs on GPUs” Standard for academic proofs
“your academic colleagues will only pay attention to your paper if it comes with a Lean or Coq proof”
Comment from 13 Dec 2025 in “String theory inspires a brilliant, baffling new math proof” “Coq (now Rocq), Isabelle, HOL Light, ACL2 and Mizar that I believe still win”
Comment from 27 Jul 2026 in “We have proof automation now” Powerful tactics and program extraction
“I've found Coq's tactics more powerful and ergonomic”
Comment from 27 Apr 2026 in “"Why not just use Lean?"” “Well Coq has program extraction built in.”
Comment from 7 Jan 2026 in “Formal Methods Only Solve Half My Problems”
What people warn about
Each mark is one comment
Proofs hard to read and maintain
“they seem deliberately designed to require you to use a context explorer to have any hope of understanding the proof at all”
Comment from 3 Mar 2026 in “When AI Writes the Software, Who Verifies It?” “Most proofs are basically write-only and impossible to maintain”
Comment from 18 Sep 2026 in “Bend 2 and the Vibe-Coding Trap” “I couldn’t make heads or tails of them”
Comment from 28 Apr 2026 in “"Why not just use Lean?"” Awkward syntax and code conversion
“Using LEAN or Coq requires you to basically convert your code to LEAN/Coq before you can start proving anything”
Comment from 23 Feb 2026 in “Lean 4: How the theorem prover works and why it's the new competitive edge in AI” “It's a bit of an awkward syntax to get a reliable assembler.”
Comment from 27 Nov 2025 in “Coq: The World's Best Macro Assembler? (2013) [pdf]” “it feels a little harder than it should be”
Comment from 18 Apr 2026 in “Coq theorem prover is now called Rocq”
Other proof assistants people recommend
The four most recommended other proof assistants, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
See all 8 proof assistants, rankedWhat people said
30 of the 33 comments that mention it, newest first. Each links to the original comment.
“Most proofs are basically write-only and impossible to maintain”
“Prove your code directly in Lean or Coq or leave it.”
“Might be worth another shot”
“the proofs in RCoq have a more pen-and-paper proof feel to them”
“Coq and Isabelle have also had 'prove False' bugs”
“Use Coq or Isabelle or any other decent theorem prover.”
“Coq (now Rocq), Isabelle, HOL Light, ACL2 and Mizar that I believe still win”
“They are cleaner mathematically, which means AI has a better chance with them.”
“ask your agent to verify critical protocols with formal proof in TLA+/lean/coq”
“I couldn’t make heads or tails of them”
“Certainly nowhere near where Coq and Lean are.”
“I've found Coq's tactics more powerful and ergonomic”
“it feels a little harder than it should be”
“I love being able to put my brain cells at lean, coq, haskell.”
“the selling point of that language is that if it compiles, then it's guaranteed to work”
“Lean and Coq might not be the right choice.”
“technically impressive but adoption-starved”
“they seem deliberately designed to require you to use a context explorer to have any hope of understanding the proof at all”
“Using LEAN or Coq requires you to basically convert your code to LEAN/Coq before you can start proving anything”
“The proof checker is much more ruthless than the rust compiler.”
“since the type system is comprehensive enough to force you to actually think about what you really want”
“that's why it's way better than the likes of TLA+”
“Well Coq has program extraction built in.”
“your academic colleagues will only pay attention to your paper if it comes with a Lean or Coq proof”
“Well if they used coq, maybe it would not have happened!”
“The thing that would really make sense is a proved language like Coq or Promela”
“Looks very promising! There is definitely something here!”
“It's a bit of an awkward syntax to get a reliable assembler.”
“The Coq language's rigor really helps with something like this.”
“there is probably good reason why no "real world" programs are written in languages with proper type systems”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.