[Haskell-cafe] Textbook example of instance Foldable ((,) a)

Dear Cafe - you might find this entertaining: an error in my code that cost me some hours (most Pictures are equal?) until I finally realized instance Eq a => Eq (Picture a) where p == q = dim p == dim q - && all (\ i -> contents p i == contents q i) (bounds p) + && all (\ i -> contents p i == contents q i) (A.range $ bounds p) Henning already called this "Matlab league" behaviour, https://mail.haskell.org/pipermail/libraries/2016-February/026678.html Well it's just a fun observation now, I am not implying anything. Enjoy! - J. Link to full source: https://gitlab.imn.htwk-leipzig.de/autotool/all0/-/issues/660#note_24567