#15921: Foldable.maximumBy uses counter-intuitive ordering -------------------------------------+------------------------------------- Reporter: qqwy | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 Keywords: List | Operating System: Unknown/Multiple maximumBy minimumBy | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs Data.List.maximumBy (Data.Ord.comparing snd) [(0, 1), (3, 2), (2, 2), (1, 1)] }}} What do you expect the outcome to be? All Haskell-programmers I know that I asked this question, would answer, based on their intuition, `(3, 2)`. However, this is not the behaviour that `Data.List.maximumBy` currently has: Instead, `(2, 2)` (the ''last'' occurrence of a 'maximum' element) is kept. Furthermore, this behaviour is different from the one used by `Data.List.minimumBy`. I would therefore like to request: - If its behaviour is unintentionally different from `minimumBy`, alter the implementation to match it. - If its behaviour is intentionally the opposite, this should be specified in the documentation. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15921 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler