Hi Café! I was wondering if anyone knew of a centralised list of occurrences where GHC Haskell stops upholding η-equivalence. I am interested in both type changes and operational semantics. So far I've collected the following things: * Rank-2 types * Monomorphism restriction * The presence of seq * Non-pedantic bottoms One source is the GHC Manual¹, and Neil Mitchell pointed me to the list of bugs and limitations of HLint². If you have other examples, or explanations of the mechanisms at play here, I would be very interested, and intend to upstream those in the GHC manual. Cheers, Hécate [¹] https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/bugs.html#ex... [²] https://github.com/ndmitchell/hlint#bugs-and-limitations -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD